Effects of different amounts and type of diet during weaning-to-estrus interval on reproductive performance of primiparous and multiparous sows.

During weaning-to-estrus interval (WEI), the sows are usually fed with high feed level to improve the reproductive performance. However, the WEI has been reduced over the years which may reduce the impact of feed level on performance in the modern genetic lines. The aim of this study was to evaluate the effect of two feeding levels (moderate feeding level (MFL): 2.7 kg/day and high feeding level (HFL): 4.3 kg/day) and two diet types (gestation: 13.67 MJ/kg of metabolizable energy (ME) and 0.62% of standard ileal digestible lysine (SID Lys) and lactation: 14.34 MJ ME/kg and 1.20% of SID Lys) offered during the WEI on reproductive performance. In total, 19.0% of sows were excluded from the analysis due to feed intake below 75% (9.6% and 28.5% in MFL and HFL groups, respectively), remaining 254 primiparous and 806 multiparous sows. Follicular size and change in BW were measured in subsamples of 180 and 227 females, respectively. Data were analyzed considering the sow as the experimental unit. Feeding level, diet type, parity and their interactions were included as fixed effects, whereas the day of weaning was considered as a random effect. The feed intake of MFL and HFL groups averaged 2.5 ± 0.02 and 3.8 ± 0.02 kg/day, respectively. There was an interaction between feeding level and parity for daily feed intake. Within HFL, multiparous sows consumed 181 g/day more than primiparous sows (P < 0.01), but no difference was observed within MFL (P > 0.05). Both primiparous and multiparous sows lost proportionally less weight when fed HFL than MFL gestation diet during WEI. The percentage of weight loss was lower in HFL than in the MFL group in multiparous sows fed the lactation diet. The WEI was not affected by feeding level, diet type or its interaction (P > 0.05), but it was longer in primiparous than in multiparous sows (P = 0.001). There was no effect of feeding level, diet type, parity or their interactions on anestrus and farrowing rates. Multiparous sows showed greater follicular size, and greater numbers of total born and born alive piglets in the subsequent cycle than primiparous sows (P < 0.05). In conclusion, feeding weaned primiparous and multiparous sows with 4.3 kg/day of a gestation (58.78 MJ ME and 26.66 g SID Lys) or a lactation diet (61.66 MJ ME and 51.60 g SID Lys) does not improve follicular size and reproductive performance in the subsequent cycle.

Impact of housing nursery pigs according to body weight on the onset of feed intake, aggressive behavior, and growth performance.

Housing nursery pigs according to body weight is an observed common practice in production systems and, supposedly, improves growth performance and reduces body weight (BW) variation. This 42-day study evaluated the effects of housing nursery pigs according to BW on performance, onset of feed intake, and aggressive behavior. A total of 504 pigs were ranked by BW at weaning and categorized into three groups of 168 pigs each: light, medium, and heavy. Pigs were randomly distributed to unsorted pens (Unsorted) containing 6 pigs of each weight group and sorted pens with 18 pigs from just one group per pen (Sorted). From weaning to day 3, pigs were fed a diet containing 1% iron oxide dye and rectal swabs presenting red coloration were evaluated to assess feed intake onset. Eight pens were video recorded to evaluate aggressive behavior. Sorted-Heavy pigs delayed the onset of feed intake (P ≤ 0.011) and presented more aggressive behaviors than Sorted-Light and Sorted-Medium pigs (P ≤ 0.036). In Unsorted, onset of feed intake showed no differences between weight categories. Also, no differences were observed for aggressive behavior between Sorted and Unsorted. Final BW showed no differences between Sorted and Unsorted pigs. The within-pen weight coefficient variation (CV) was slightly different (P = 0.042) between Sorted and Unsorted pigs (13.3 and 15.6%, respectively), at the end of the study. Thus, sorting nursery pigs by BW did not improve growth performance and also, induce a lag of post-weaning feed intake onset and increased fights in Heavy pigs.

Use of testicular tone and echogenicity in identifying boars with low sperm quality / Uso de tônus e ecogenicidade testiculares na identificação de reprodutores suínos com baixa qualidade espermática

This study aimed to evaluate the use of some testicular traits to identify boars with low sperm morphological quality. The consistency (scores from 1 to 5), tone with tonometry (mm), parenchyma echogenicity and heterogeneity with ultrasound (pixel) were assessed in 402 mature boars (18.5 months on average). Sperm abnormality thresholds (≤ 25% of total sperm abnormalities, ≤ 5% of heads, acrosome, neck or midpiece defects, ≤ 10% tail defects, and 15% cytoplasmic droplets) were used to classify boars as approved or disapproved. Three classes of testicular traits were formed (extremely low and high values, approximately 15% each, were kept in separated classes). When the traits were individually evaluated, fewer boars were approved if the echogenicity or heterogeneity were high, or if the tone was rigid. When evaluated in combination, the interaction between heterogeneity and tone, and between heterogeneity and echogenicity were significant. The high heterogeneity combined with soft tone or with hypo-echogenicity resulted in lower approval of boars. Tonometry and ultrasonography have a moderate potential to be included in breeding soundness examination of boars. When combined, they provide more reliable information about the impact of testicular parenchymal alterations on morphology of sperm cells.(AU)

O estudo objetivou avaliar o uso de características testiculares para identificar reprodutores com baixa qualidade de morfologia espermática. A consistência (escore de 1 a 5), o tônus por tonometria (mm), a ecogenicidade e a heterogeneidade do parênquima testicular por ultrassonografia (pixel) foram avaliados em 402 machos suínos maduros (18,5 meses, em média). Limiares máximos de anormalidades espermáticas (≤ 25% de defeitos totais, ≤ 5% de defeitos de cabeça, acrossoma, colo e peça intermediária, ≤ 10% de defeitos de cauda e 15% de gota citoplasmática) foram utilizados para classificar os machos como aprovados ou reprovados. Três classes de características testiculares foram formadas (valores extremamente baixos e altos, aproximadamente 15% em cada, foram mantidos em classes separadas). Quando as características testiculares foram avaliadas individualmente, menos machos foram aprovados se a ecogenicidade ou a heterogeneidade foram altas, ou se o tônus era rígido. Quando avaliadas em combinação, a interação entre heterogeneidade e tônus e a interação entre heterogeneidade e ecogenicidade foram significativas. A alta heterogeneidade combinada com testículos flácidos ou com testículos hipoecogênicos resultou em menor aprovação de cachaços. A tonometria e a ultrassonografia possuem potencial moderado para serem incluídas no exame andrológico de cachaços. Quando combinadas, as técnicas fornecem uma informação mais consistente do impacto das alterações do parênquima testicular na morfologia das células espermáticas.(AU)

Use of testicular tone and echogenicity in identifying boars with low sperm quality / Uso de tônus e ecogenicidade testiculares na identificação de reprodutores suínos com baixa qualidade espermática

This study aimed to evaluate the use of some testicular traits to identify boars with low sperm morphological quality. The consistency (scores from 1 to 5), tone with tonometry (mm), parenchyma echogenicity and heterogeneity with ultrasound (pixel) were assessed in 402 mature boars (18.5 months on average). Sperm abnormality thresholds (≤ 25% of total sperm abnormalities, ≤ 5% of heads, acrosome, neck or midpiece defects, ≤ 10% tail defects, and 15% cytoplasmic droplets) were used to classify boars as approved or disapproved. Three classes of testicular traits were formed (extremely low and high values, approximately 15% each, were kept in separated classes). When the traits were individually evaluated, fewer boars were approved if the echogenicity or heterogeneity were high, or if the tone was rigid. When evaluated in combination, the interaction between heterogeneity and tone, and between heterogeneity and echogenicity were significant. The high heterogeneity combined with soft tone or with hypo-echogenicity resulted in lower approval of boars. Tonometry and ultrasonography have a moderate potential to be included in breeding soundness examination of boars. When combined, they provide more reliable information about the impact of testicular parenchymal alterations on morphology of sperm cells.(AU)

O estudo objetivou avaliar o uso de características testiculares para identificar reprodutores com baixa qualidade de morfologia espermática. A consistência (escore de 1 a 5), o tônus por tonometria (mm), a ecogenicidade e a heterogeneidade do parênquima testicular por ultrassonografia (pixel) foram avaliados em 402 machos suínos maduros (18,5 meses, em média). Limiares máximos de anormalidades espermáticas (≤ 25% de defeitos totais, ≤ 5% de defeitos de cabeça, acrossoma, colo e peça intermediária, ≤ 10% de defeitos de cauda e 15% de gota citoplasmática) foram utilizados para classificar os machos como aprovados ou reprovados. Três classes de características testiculares foram formadas (valores extremamente baixos e altos, aproximadamente 15% em cada, foram mantidos em classes separadas). Quando as características testiculares foram avaliadas individualmente, menos machos foram aprovados se a ecogenicidade ou a heterogeneidade foram altas, ou se o tônus era rígido. Quando avaliadas em combinação, a interação entre heterogeneidade e tônus e a interação entre heterogeneidade e ecogenicidade foram significativas. A alta heterogeneidade combinada com testículos flácidos ou com testículos hipoecogênicos resultou em menor aprovação de cachaços. A tonometria e a ultrassonografia possuem potencial moderado para serem incluídas no exame andrológico de cachaços. Quando combinadas, as técnicas fornecem uma informação mais consistente do impacto das alterações do parênquima testicular na morfologia das células espermáticas.(AU)

Performance of low birth-weight piglets upon protein-energy and/or colostrum supplementation / Desempenho de leitões de baixo peso ao nascimento submetidos à suplementação proteico-energética com ou sem colostro

The study aimed to investigate the effect of oral protein-energy supplement (OPES) and/or extra colostrum within the first few hours of life on the survival and growth performance of low birth-weight piglets during the suckling period. Based upon nutritional strategy, low-birth-weight piglets (804−1309g) were randomly allocated into four groups: C0S0 (control group, n= 300) - no supplementation; C1S0 (n= 299) - supplementation with 50mL of a colostrum pool through an orogastric tube; C0S1 (n= 298) - oral supplementation with 8mL oral OPES; C1S1 (n= 297) - supplementation with both 50mL of colostrum and 8mL of OPES. The piglets' body weight was monitored at birth, 24h after birth, on day 7, day 14 and day 20 post-partum. Both colostrum and protein-energy supplementations did not affect (P>0.05) colostrum intake (253.6g; 259.4g; 259.4g; 263.8g for C0S0, C1S0, C0S1, C1S1, respectively), weight gain during the first 24h (62.6g; 68.3g; 67.1g and 69.8g for C0S0, C1S0, C0S1, C1S1, respectively) and pre-weaning mortality (11.3%, 11.4%, 12.4% and 9.4% for C0S0, C1S0, C0S1, C1S1, respectively). Administration of OPES increased (P= 0.032) the average daily weight gain from birth till weaning (189.1 vs. 182.3g) and tended to increase the weight of the piglets (P= 0.060) at weaning (4893.1 vs. 4746.4g for OPES and no OPES, respectively). In conclusion, nutritional manipulation does not affect colostrum intake and pre-weaning mortality of low birth-weight piglets. However, body weight gain during the suckling period and the weight at weaning were observed to be marginally improved by administration of OPES.(AU)

O objetivo do trabalho foi avaliar o efeito da suplementação oral de suplemento proteico-energético (OPES) e/ou colostro adicional nas primeiras horas de vida sobre a sobrevivência e o desempenho de leitões de baixo peso na fase de maternidade. Foram utilizados leitões com peso entre 804 e 1.309g ao nascimento, alocados aleatoriamente em quatro grupos, de acordo com a estratégia nutricional: C0S0 (grupo controle, n= 300) - sem suplementação; C1S0 (n= 299) - fornecimento de 50mL de colostro, via sonda orogástrica; C0S1 (n=298) - fornecimento de 8mL de OPES; C1S1 (n= 297) - fornecimento de 50mL de colostro + 8mL de OPES. Os leitões foram pesados ao nascimento, 24h, e nos dias sete, 14 e 20 de vida. O fornecimento de colostro ou de OPES não afetou (P>0,05) o consumo de colostro (253,6g; 259,4g; 259,4g; 263,8g para C0S0, C1S0, C0S1, C1S1, respectivamente), o ganho de peso nas primeiras 24h (62,6g; 68,3g; 67,1g e 69,8g para C0S0, C1S0, C0S1, C1S1, respectivamente) e a taxa de mortalidade (11,3%, 11,4%, 12,4% e 9,4% para C0S0, C1S0, C0S1, C1S1, respectivamente). A suplementação com OPES aumentou (P<0,05) o ganho de peso diário do nascimento ao desmame (189,1g vs. 182,3g) e tendeu a aumentar o peso dos leitões (P=0,060) ao desmame (4893,1 vs. 4746,4g para OPES e sem OPES, respectivamente). Conclui-se que a manipulação nutricional de leitões de baixo peso ao nascimento não afeta o consumo de colostro e a mortalidade pré-desmame. No entanto, a administração de OPES aumentou levemente o ganho de peso na maternidade e o peso ao desmame.(AU)

Performance of low birth-weight piglets upon protein-energy and/or colostrum supplementation / Desempenho de leitões de baixo peso ao nascimento submetidos à suplementação proteico-energética com ou sem colostro

The study aimed to investigate the effect of oral protein-energy supplement (OPES) and/or extra colostrum within the first few hours of life on the survival and growth performance of low birth-weight piglets during the suckling period. Based upon nutritional strategy, low-birth-weight piglets (804−1309g) were randomly allocated into four groups: C0S0 (control group, n= 300) - no supplementation; C1S0 (n= 299) - supplementation with 50mL of a colostrum pool through an orogastric tube; C0S1 (n= 298) - oral supplementation with 8mL oral OPES; C1S1 (n= 297) - supplementation with both 50mL of colostrum and 8mL of OPES. The piglets' body weight was monitored at birth, 24h after birth, on day 7, day 14 and day 20 post-partum. Both colostrum and protein-energy supplementations did not affect (P>0.05) colostrum intake (253.6g; 259.4g; 259.4g; 263.8g for C0S0, C1S0, C0S1, C1S1, respectively), weight gain during the first 24h (62.6g; 68.3g; 67.1g and 69.8g for C0S0, C1S0, C0S1, C1S1, respectively) and pre-weaning mortality (11.3%, 11.4%, 12.4% and 9.4% for C0S0, C1S0, C0S1, C1S1, respectively). Administration of OPES increased (P= 0.032) the average daily weight gain from birth till weaning (189.1 vs. 182.3g) and tended to increase the weight of the piglets (P= 0.060) at weaning (4893.1 vs. 4746.4g for OPES and no OPES, respectively). In conclusion, nutritional manipulation does not affect colostrum intake and pre-weaning mortality of low birth-weight piglets. However, body weight gain during the suckling period and the weight at weaning were observed to be marginally improved by administration of OPES.(AU)

O objetivo do trabalho foi avaliar o efeito da suplementação oral de suplemento proteico-energético (OPES) e/ou colostro adicional nas primeiras horas de vida sobre a sobrevivência e o desempenho de leitões de baixo peso na fase de maternidade. Foram utilizados leitões com peso entre 804 e 1.309g ao nascimento, alocados aleatoriamente em quatro grupos, de acordo com a estratégia nutricional: C0S0 (grupo controle, n= 300) - sem suplementação; C1S0 (n= 299) - fornecimento de 50mL de colostro, via sonda orogástrica; C0S1 (n=298) - fornecimento de 8mL de OPES; C1S1 (n= 297) - fornecimento de 50mL de colostro + 8mL de OPES. Os leitões foram pesados ao nascimento, 24h, e nos dias sete, 14 e 20 de vida. O fornecimento de colostro ou de OPES não afetou (P>0,05) o consumo de colostro (253,6g; 259,4g; 259,4g; 263,8g para C0S0, C1S0, C0S1, C1S1, respectivamente), o ganho de peso nas primeiras 24h (62,6g; 68,3g; 67,1g e 69,8g para C0S0, C1S0, C0S1, C1S1, respectivamente) e a taxa de mortalidade (11,3%, 11,4%, 12,4% e 9,4% para C0S0, C1S0, C0S1, C1S1, respectivamente). A suplementação com OPES aumentou (P<0,05) o ganho de peso diário do nascimento ao desmame (189,1g vs. 182,3g) e tendeu a aumentar o peso dos leitões (P=0,060) ao desmame (4893,1 vs. 4746,4g para OPES e sem OPES, respectivamente). Conclui-se que a manipulação nutricional de leitões de baixo peso ao nascimento não afeta o consumo de colostro e a mortalidade pré-desmame. No entanto, a administração de OPES aumentou levemente o ganho de peso na maternidade e o peso ao desmame.(AU)

Colostrum yield and litter performance in multiparous sows subjected to farrowing induction.

The consumption of colostrum at a low level can compromise the survival and growth of piglets. Therefore, this study aimed to evaluate the effect of farrowing induction on colostrum yield, IgG concentration and the survival and performance of piglets until the weaning. Sows of parity 3 to 7 were assigned into two groups: Control (n = 48), sows with spontaneous farrowing; and induction (n = 48), sows induced to farrow on day 114 of gestation with a PGF2 analogue. Colostrum and blood samples were collected from the sows, at farrowing and 24 hr later. Blood samples from the piglets were collected at 24 hr after birth. The performance of the piglets was evaluated in a subsample of 28 litters from each group. All piglets were weighed at 7, 14 and 20 days of age. The farrowing length, the number of piglets born alive, stillborn piglets, weight at birth, litter weight at birth and colostrum yield were not significantly affected (p > .05) by farrowing induction. There was no difference between the groups (p > .05) in the percentage of sows with obstetric interventions. Serum IgG concentration, in both sows and piglets, and colostrum IgG concentration were similar between the groups (p > .05). Furthermore, survival rate, piglet weight and litter weight at 7, 14 and 20 days of age were also similar between the groups (p > .05). Therefore, it can be concluded that the farrowing induction performed on day 114 of gestation does not affect the colostrum yield, the IgG concentration in colostrum and serum of piglets, and the litter performance until the weaning.

Fixed-time post-cervical artificial insemination in weaned sows following buserelin use combined with/without eCG.

Fixed-time post-cervical artificial insemination (FTAI) drastically reduces labour requirements and increases the use of boars with higher genetic merit. This study evaluated the efficiency of eCG administration combined with/without the GnRH agonist buserelin for the induction and synchronization of ovulation in weaned sows submitted to FTAI. The sows were allocated into three groups. In the control group, the first artificial insemination was performed at the onset of oestrus and repeated every 24 hr. In the eCG+GnRH group, sows received 600 IU eCG at weaning and buserelin (10 µg) after 86-89 hr of eCG, and in the GnRH group, sows received only buserelin after 86-89 hr of weaning. The hormone-treated sows received a single FTAI after 30-33 hr of buserelin application. All the sows were inseminated with homospermic doses (1.5 × 109  sperm cells/50 ml). The interval between weaning and ovulation was shorter (p < .05) in the eCG+GnRH (133.3 hr) and GnRH (135.9 hr) groups than the control (141.5 hr) group. In the eCG+GnRH group, the sows ovulated earlier (p < .05) than those in the GnRH group (44.5 vs. 48.2 hr after buserelin administration). The reproductive performance of GnRH sows was not compromised when only sows exhibiting oestrus at the time of insemination were considered, but lower farrowing rate and smaller litter size were observed in eCG+GnRH sows. The reproductive performance of eCG+GnRH sows was primarily compromised because the insemination was performed outside the optimal time relative to ovulation; therefore, it is advisable to inseminate them before 116-122 hr after weaning.

Factors influencing colostrum yield by sows / Fatores que influenciam a produção de colostro em porcas

An adequate colostrum intake, in order to ensure the survival and weight gain of piglets, depends on the sow's ability to produce enough colostrum for the whole litter. The aim of this study was to evaluate factors involved in colostrum yield (CY) variability related to the sow, the litter and the farrowing process. The experiment was conducted with 96 Camborough 25(r) sows of parities one to seven, whose farrowing was spontaneous. Colostrum production of each sow was estimated by summing up the colostrum intake of each piglet in the litter, estimated by an equation that takes into account the birth weight and weight gain during the first 24h of life. The multiple regression model explained 28% of variation in CY, with 24% and 4% respectively of variation being explained by the litter birth weight and the width of the first mammary glands. Litter birth weight was positively correlated with the number of total born (r= 0.73) and born alive piglets (r= 0.83). When categorised into two groups of colostrum yield (LOWCY; ≤3.4kg; n= 46 vs HIGHCY; >3.4kg; n= 50), LOWCY sows had fewer total born and born alive piglets and lighter litters (P<0.05). The logistic regression analysis showed that sows from parities 1, 2 and >3 had greater odds (P≤0.05) of belonging to the LOWCY group than parity 3 sows. Sows with two or more obstetrical interventions had higher odds (P<0.05) of belonging to the LOWCY group than sows without interventions during farrowing. The higher colostrum yield observed in sows of parity 3 and sows with less than two obstetrical interventions during farrowing was associated with a greater number of nursed piglets. This study showed that total birth weight of born alive piglets is the most important factor involved in colostrum yield variability, indirectly representing the number of piglets nursed by the sow.(AU)

Um consumo adequado de colostro, para assegurar a sobrevivência e o ganho de peso, dos leitões, depende da capacidade da porca em produzir colostro suficiente para toda a leitegada. O objetivo deste estudo foi determinar fatores relacionados com a porca, com a leitegada ou com o parto que possam influenciar a produção de colostro (PC). O experimento foi conduzido com 96 porcas Camborough 25, de ordem de parto (OP) 1 a 7, cujo parto foi espontâneo. A produção de colostro das porcas foi estimada pela soma do consumo individual de colostro pelos leitões, o qual foi estimado por equação que considera o peso ao nascimento e o ganho de peso nas primeiras 24h de vida. Por meio de modelo de regressão múltipla, 28% da variação na PC foi explicada pelo peso da leitegada (24%) e pela largura do primeiro par de glândulas mamárias (4%). O peso da leitegada foi positivamente correlacionado com o número total de leitões nascidos (r= 0.73) e com o número de leitões nascidos vivos (r= 0.83). Quando separadas em dois grupos de PC (BAIXAPC; ≤3.4kg; n=46 e ALTAPC; >3.4kg; n=50), as porcas do grupo BAIXAPC tiveram menor número total de leitões nascidos, menor número de leitões nascidos vivos e leitegadas mais leves (P<0.05). Por regressão logística, foi observado que porcas da OP 1, 2 e >3 tiveram maior chance (P≤0.05) de pertencer ao grupo BAIXAPC do que porcas de OP 3. Porcas com duas ou mais intervenções obstétricas tiveram maior chance (P<0.05) de pertencer ao grupo BAIXAPC do que as porcas sem intervenção durante o parto. A maior PC observada nas porcas de OP 3 e nas porcas com menos intervenções obstétricas foi associada com um maior número de leitões amamentados. Foi mostrado, neste estudo, que o peso total da leitegada viva, o qual indiretamente representa o número de leitões amamentados pela porca, é o fator mais importante envolvido na produção de colostro.(AU)

Single fixed-time artificial insemination in gilts and weaned sows using pLH at estrus onset administered through vulvar submucosal route.

This study evaluated the use of a single fixed-time artificial insemination (FTAI) in gilts and weaned sows using 2.5 mg of porcine luteinizing hormone (pLH) administered through vulvar submucosal route, at the onset of estrus. In experiment 1 (Exp.1), 318 pubertal gilts were assigned to two groups: control-G-no hormonal application and artificial inseminations (AIs) at 12, 36, and 60 hours after the onset of estrus if they were still in standing estrus; and FTAI-G-use of pLH at the onset of estrus and a single FTAI 12 hours later. In experiment 2 (Exp. 2), 309 weaned sows were assigned to three groups: Control-S-no hormone application and AIs at 0, 24, and 48 hours after the onset of estrus if they were still in standing estrus; FTAI-NH-no hormone application and a single FTAI at 24 hours after the onset of estrus, and FTAI-pLH-use of pLH at the onset of estrus and a single FTAI 24 hours later. Transabdominal real time B-mode ultrasonography was performed to determine whether the insemination had been performed within 24 hours before ovulation, considered as the optimal interval. In Exp. 1, ultrasound evaluation (12-hour intervals) was carried out to determine the interval between the onset of estrus and ovulation. In both experiments, 2 × 10(9) sperm cells in 80 mL were used to perform cervical and postcervical deposition of semen in gilts and sows, respectively. Compared with control-G, FTAI-G gilts had shorter (P < 0.05) duration of estrus (57.7 vs. 61.2 hours) and interval between the onset of estrus and ovulation (36.3 vs. 42.3 hours). The adjusted farrowing rate (AFR) was lower (P < 0.05) in FTAI-G (86.0%) compared with control-G (93.5%), but total piglets born (TPB) did not differ between these groups (12.3 vs. 12.5 piglets). Within the FTAI-G group, the AFR was lower (P < 0.05) in the presence (50.0%) than in the absence (94.9%) of semen backflow during AI. Also in the FTAI-G group, the insemination outside the optimal interval reduced (P < 0.05) the TPB (10.5 vs. 12.9 piglets) in comparison with gilts inseminated within the optimal interval. In Exp. 2, there were no differences in the AFR (Control-S: 94.1%; FTAI-NH: 86.1%; FTAI-pLH: 88.0%) and TPB (Control-S: 12.8; FTAI-NH: 12.7, and FTAI-pLH: 12.0 piglets) among treatments. The presence of semen backflow reduced (P < 0.05) the TPB in FTAI-pLH and FTAI-NH sows. In the FTAI-pLH, a single insemination performed too late relative to ovulation reduced the AFR (P < 0.05) compared with sows inseminated within the optimal interval. In conclusion, 2.5-mg pLH applied at the vulvar submucosa at the onset of estrus advances the ovulation in gilts, but a single FTAI performed 12 hours later reduces the farrowing rate. A single FTAI performed at 24 hours after the onset of estrus in weaned sows does not affect their reproductive performance, regardless of pLH application.

Factors influencing colostrum yield by sows / Fatores que influenciam a produção de colostro em porcas

An adequate colostrum intake, in order to ensure the survival and weight gain of piglets, depends on the sow's ability to produce enough colostrum for the whole litter. The aim of this study was to evaluate factors involved in colostrum yield (CY) variability related to the sow, the litter and the farrowing process. The experiment was conducted with 96 Camborough 25(r) sows of parities one to seven, whose farrowing was spontaneous. Colostrum production of each sow was estimated by summing up the colostrum intake of each piglet in the litter, estimated by an equation that takes into account the birth weight and weight gain during the first 24h of life. The multiple regression model explained 28% of variation in CY, with 24% and 4% respectively of variation being explained by the litter birth weight and the width of the first mammary glands. Litter birth weight was positively correlated with the number of total born (r= 0.73) and born alive piglets (r= 0.83). When categorised into two groups of colostrum yield (LOWCY; ≤3.4kg; n= 46 vs HIGHCY; >3.4kg; n= 50), LOWCY sows had fewer total born and born alive piglets and lighter litters (P<0.05). The logistic regression analysis showed that sows from parities 1, 2 and >3 had greater odds (P≤0.05) of belonging to the LOWCY group than parity 3 sows. Sows with two or more obstetrical interventions had higher odds (P<0.05) of belonging to the LOWCY group than sows without interventions during farrowing. The higher colostrum yield observed in sows of parity 3 and sows with less than two obstetrical interventions during farrowing was associated with a greater number of nursed piglets. This study showed that total birth weight of born alive piglets is the most important factor involved in colostrum yield variability, indirectly representing the number of piglets nursed by the sow.(AU)

Um consumo adequado de colostro, para assegurar a sobrevivência e o ganho de peso, dos leitões, depende da capacidade da porca em produzir colostro suficiente para toda a leitegada. O objetivo deste estudo foi determinar fatores relacionados com a porca, com a leitegada ou com o parto que possam influenciar a produção de colostro (PC). O experimento foi conduzido com 96 porcas Camborough 25, de ordem de parto (OP) 1 a 7, cujo parto foi espontâneo. A produção de colostro das porcas foi estimada pela soma do consumo individual de colostro pelos leitões, o qual foi estimado por equação que considera o peso ao nascimento e o ganho de peso nas primeiras 24h de vida. Por meio de modelo de regressão múltipla, 28% da variação na PC foi explicada pelo peso da leitegada (24%) e pela largura do primeiro par de glândulas mamárias (4%). O peso da leitegada foi positivamente correlacionado com o número total de leitões nascidos (r= 0.73) e com o número de leitões nascidos vivos (r= 0.83). Quando separadas em dois grupos de PC (BAIXAPC; ≤3.4kg; n=46 e ALTAPC; >3.4kg; n=50), as porcas do grupo BAIXAPC tiveram menor número total de leitões nascidos, menor número de leitões nascidos vivos e leitegadas mais leves (P<0.05). Por regressão logística, foi observado que porcas da OP 1, 2 e >3 tiveram maior chance (P≤0.05) de pertencer ao grupo BAIXAPC do que porcas de OP 3. Porcas com duas ou mais intervenções obstétricas tiveram maior chance (P<0.05) de pertencer ao grupo BAIXAPC do que as porcas sem intervenção durante o parto. A maior PC observada nas porcas de OP 3 e nas porcas com menos intervenções obstétricas foi associada com um maior número de leitões amamentados. Foi mostrado, neste estudo, que o peso total da leitegada viva, o qual indiretamente representa o número de leitões amamentados pela porca, é o fator mais importante envolvido na produção de colostro.(AU)

Impact of isothermic and bithermic dilution on quality of chilled boar sperm

The use of bithermic dilution protocols is increasing in artificial insemination centres; therefore, it is necessary to guarantee that the quality of insemination doses remain the same when compared to isothermic dilution protocols. Four ejaculates from each of 19 crossbreed PIC® boars were collected and assigned, in a split sample design, in three treatments: two-step bithermic dilution two-step isothermic dilutionand one-step isothermic dilution. Temperature curves for the three treatments were recorded using a temperature sensor data logger. Semen doses were prepared with a BTS extender and stored at 16°C and then used to evaluate sperm parameters with the CASA system and sperm morphology for 120 h. The temperature in semen samples submitted to a two-step bithermic dilution reached 24.6ºC after 120 min, whereas one or two-step isothermic dilution samples reached 26.4ºC and 27.4ºC, respectively. Total motility, progressive motility and BCF were influenced (P < 0.05) by the storage time but not by the dilution procedure. Total and progressive motility decreased throughout the storage time (91.0 ± 0.91 to 81.5 ± 1.08% and 74.0 ± 2.48 to 60.4 ± 2.59% from 24 h to 120 h, for MOT and PROG, respectively) whereas BCF differed between 24 and 120 h (28.6 ± 0.76 and 27.3 ± 0.79 Hz). The following motility traits were not affected by the dilution procedure or by the time of storage: DAP, DCL, DSL, VAP, VCL, VSL, STR, LIN, WOB, and ALH. At 72 h of storage, sperm morphology was not different among treatments (P > 0.05), showing an overall mean of 9.2 ±0.4 total defects. In conclusion, the bithermic dilution makes the production of artificial insemination doses faster by taking less time to reach a temperature close to that of storage, without impairing semen quality.(AU)

Impact of isothermic and bithermic dilution on quality of chilled boar sperm

The use of bithermic dilution protocols is increasing in artificial insemination centres; therefore, it is necessary to guarantee that the quality of insemination doses remain the same when compared to isothermic dilution protocols. Four ejaculates from each of 19 crossbreed PIC® boars were collected and assigned, in a split sample design, in three treatments: two-step bithermic dilution two-step isothermic dilutionand one-step isothermic dilution. Temperature curves for the three treatments were recorded using a temperature sensor data logger. Semen doses were prepared with a BTS extender and stored at 16°C and then used to evaluate sperm parameters with the CASA system and sperm morphology for 120 h. The temperature in semen samples submitted to a two-step bithermic dilution reached 24.6ºC after 120 min, whereas one or two-step isothermic dilution samples reached 26.4ºC and 27.4ºC, respectively. Total motility, progressive motility and BCF were influenced (P 0.05), showing an overall mean of 9.2 ±0.4 total defects. In conclusion, the bithermic dilution makes the production of artificial insemination doses faster by taking less time to reach a temperature close to that of storage, without impairing semen quality.

New Artificial Insemination Technologies for Swine.

Better efficiency in swine artificial insemination (AI) is accomplished by reducing the necessary number of sperm cells and achieving high reproductive performance. Some strategies have been developed for use under field conditions, such as the site of sperm deposition (post-cervical AI), a single AI with control of oestrus and ovulation (fixed-time AI), and the better use of high genetic merit boars, to spread their genes as much as possible. To apply these technologies, it is important to understand some anatomical limits, physiological aspects and farm requirements. In this review, we point out some strategies to achieve higher efficiency on the use of sperm for AI technology application in swine species.

Effect of body development from first insemination to first weaning on performance and culling until the third farrowing of Landrace x Large White swine females / Efeito do desenvolvimento corporal desde a primeira inseminação até o primeiro desmame no desempenho e descarte até o terceiro parto de fêmeas suínas Landrace x Large White

The aim of this study was to verify the association of sow body weight development until the 1st weaning with reproductive performance, piglet production and culling rate until the 3rd farrowing in 196 primiparous sows using logistic regression models. Each 10kg increase in weight gain in the 1st pregnancy (OR= 0.63), weight at 1st farrowing (OR= 0.70), weight at the 1st weaning (OR= 0.73) or weight gain from the 1st artificial insemination (AI) to the 1st weaning (OR= 0.67) decreased the percentage of primiparous sows with long weaning-to-oestrus interval - WOI (>5 days). An increasing lactation length and an increase in the number of weaned piglets were responsible for respectively decreasing (OR= 0.77-0.80, per day of lactation) and increasing (OR= 1.52-1.59, per piglet weaned) the percentage of sows with long WOI. Sows with <159.5kg at weaning had higher odds of non-farrowing (NFR) compared to sows with >170kg (OR= 4.73). Sows with <17.5kg of gain from the 1st AI to the 1st weaning had higher odds (OR= 4.88) of NFR than sows gaining >30kg. Each additional lactation day decreased the NFR (OR= 0.74). Females weighing <139kg at the 1st AI had higher percentages of small numbers of total born in the second parity (STB2, OR= 2.00) and over three parities (OR= 3.28) compared to those weighing ≥139kg. Sows with weight gain <25kg at the 1st pregnancy had higher odds of STB2 (OR= 3.01) compared to sows gaining >35kg. Each 10kg of increase in weight at the 1st weaning or in weight gain from the 1st AI to the 1st weaning decreased the total culling rate (OR= 0.71 and 0.73, respectively) and culling for reproductive reasons (OR= 0.57 and 0.61, respectively). The culling rate until the 3rd farrowing was also increased in sows with a smaller first litter size. The results show that not only reaching a minimum weight at the 1st AI but also having an adequate body weight gain until the 1st weaning is important for the reproductive performance, productivity and retention of Landrace x Large White Danbred sows in the herd.(AU)

O objetivo do estudo foi verificar, com modelos de regressão logística, a associação entre características de desenvolvimento corporal até o 1º desmame com o desempenho reprodutivo, produção de leitões e taxa de remoção até o 3º parto de 196 fêmeas suínas primíparas. Houve redução nas chances de as fêmeas terem intervalo desmame-estro (IDE) longo (>5 dias) a cada 10kg de aumento no ganho de peso na 1ª gestação - GPG1 (razão de chance - RC = 0,63), peso no 1º parto - PP1 (RC= 0,70), peso no 1º desmame - PD1 (RC= 0,73) ou ganho de peso da 1ª inseminação artificial (IA) ao 1º desmame - GPIAD1 (RC= 0,67). O percentual de porcas com IDE longo reduziu com o aumento da duração da lactação (RC= 0,77-0,80, por dia de lactação) e aumentou com o aumento no número de leitões desmamados (RC= 1,52-1,59, por leitão desmamado). Porcas com <159,5kg ao desmame tiveram maior chance de não parir (NP) em comparação a porcas com >170 kg (RC= 4,73). Porcas com <17,5kg de GPIAD1 tiveram maior chance (RC= 4,88) de NP do que porcas ganhando >30kg. O aumento da duração da lactação reduziu a chance de NP (RC= 0,74, para cada dia). Fêmeas com <139kg na 1ª IA tiveram maior chance de terem leitegada pequena no segundo parto - LPSP (RC= 2,00) ou ao longo de 3 partos (RC= 3,28), em comparação às fêmeas com ≥139kg. Fêmeas com GPG1 <25kg tiveram maior chance de LPSP (RC= 3,01) do que fêmeas com >35kg. Houve diminuição na taxa geral de descarte (RC= 0,71 e 0,73, respectivamente) e descarte por causas reprodutivas (RC= 0,57 e 0,61, respectivamente) para cada 10kg de aumento no PD1 e GPIAD1. A taxa de descarte até o 3º parto também aumentou nas porcas com menor leitegada no primeiro parto. Os resultados mostram que, além de atingir um peso mínimo na 1ª IA, o ganho de peso entre a 1ª IA e o primeiro desmame é importante para o desempenho reprodutivo, produtividade e retenção de fêmeas Danbred Landrace x Large White no rebanho.(AU)

Effect of body development from first insemination to first weaning on performance and culling until the third farrowing of Landrace x Large White swine females / Efeito do desenvolvimento corporal desde a primeira inseminação até o primeiro desmame no desempenho e descarte até o terceiro parto de fêmeas suínas Landrace x Large White

The aim of this study was to verify the association of sow body weight development until the 1st weaning with reproductive performance, piglet production and culling rate until the 3rd farrowing in 196 primiparous sows using logistic regression models. Each 10kg increase in weight gain in the 1stpregnancy (OR= 0.63), weight at 1st farrowing (OR= 0.70), weight at the 1st weaning (OR= 0.73) or weight gain from the 1startificial insemination (AI) to the 1st weaning (OR= 0.67) decreased the percentage of primiparous sows with long weaning-to-oestrus interval - WOI (>5 days). An increasing lactation length and an increase in the number of weaned piglets were responsible for respectively decreasing (OR= 0.77-0.80, per day of lactation) and increasing (OR= 1.52-1.59, per piglet weaned) the percentage of sows with long WOI. Sows with <159.5kg at weaning had higher odds of non-farrowing (NFR) compared to sows with >170kg (OR= 4.73). Sows with <17.5kg of gain from the 1st AI to the 1st weaning had higher odds (OR= 4.88) of NFR than sows gaining >30kg. Each additional lactation day decreased the NFR (OR= 0.74). Females weighing <139kg at the 1st AI had higher percentages of small numbers of total born in the second parity (STB2, OR= 2.00) and over three parities (OR= 3.28) compared to those weighing ≥139kg. Sows with weight gain <25kg at the 1st pregnancy had higher odds of STB2 (OR= 3.01) compared to sows gaining >35kg. Each 10kg of increase in weight at the 1st weaning or in weight gain from the 1st AI to the 1st weaning decreased the total culling rate (OR= 0.71 and 0.73, respectively) and culling for reproductive reasons (OR= 0.57 and 0.61, respectively). The culling rate until the 3rdfarrowing was also increased in sows with a smaller first litter size. The results show that not only reaching a minimum weight at the 1st AI but also having an adequate body weight gain until the 1st weaning is important for the reproductive performance, productivity and retention of Landrace x Large White Danbred sows in the herd.(AU)

O objetivo do estudo foi verificar, com modelos de regressão logística, a associação entre características de desenvolvimento corporal até o 1º desmame com o desempenho reprodutivo, produção de leitões e taxa de remoção até o 3º parto de 196 fêmeas suínas primíparas. Houve redução nas chances de as fêmeas terem intervalo desmame-estro (IDE) longo (>5 dias) a cada 10kg de aumento no ganho de peso na 1ª gestação - GPG1 (razão de chance - RC = 0,63), peso no 1º parto - PP1 (RC= 0,70), peso no 1º desmame - PD1 (RC= 0,73) ou ganho de peso da 1ª inseminação artificial (IA) ao 1º desmame - GPIAD1 (RC= 0,67). O percentual de porcas com IDE longo reduziu com o aumento da duração da lactação (RC= 0,77-0,80, por dia de lactação) e aumentou com o aumento no número de leitões desmamados (RC= 1,52-1,59, por leitão desmamado). Porcas com <159,5kg ao desmame tiveram maior chance de não parir (NP) em comparação a porcas com >170 kg (RC= 4,73). Porcas com <17,5kg de GPIAD1 tiveram maior chance (RC= 4,88) de NP do que porcas ganhando >30kg. O aumento da duração da lactação reduziu a chance de NP (RC= 0,74, para cada dia). Fêmeas com <139kg na 1ª IA tiveram maior chance de terem leitegada pequena no segundo parto - LPSP (RC= 2,00) ou ao longo de 3 partos (RC= 3,28), em comparação às fêmeas com ≥139kg. Fêmeas com GPG1 <25kg tiveram maior chance de LPSP (RC= 3,01) do que fêmeas com >35kg. Houve diminuição na taxa geral de descarte (RC= 0,71 e 0,73, respectivamente) e descarte por causas reprodutivas (RC= 0,57 e 0,61, respectivamente) para cada 10kg de aumento no PD1 e GPIAD1. A taxa de descarte até o 3º parto também aumentou nas porcas com menor leitegada no primeiro parto. Os resultados mostram que, além de atingir um peso mínimo na 1ª IA, o ganho de peso entre a 1ª IA e o primeiro desmame é importante para o desempenho reprodutivo, produtividade e retenção de fêmeas Danbred Landrace x Large White no rebanho.(AU)

Use of porcine luteinizing hormone at oestrous onset in a protocol for fixed-time artificial insemination in gilts.

The aim of this study was to evaluate the effect of porcine luteinizing hormone (pLH) given at oestrous onset in gilts, by different routes and doses, on the interval between onset of oestrus and ovulation (IOEO) and reproductive performance using a single fixed-time artificial insemination (FTAI). A total of 153 gilts were submitted to oestrous detection at 8-h intervals and assigned to three groups: control - without hormone application and inseminated at 0, 24 and 48 h after oestrous onset; VS2.5FTAI - 2.5 mg pLH by the vulvar submucosal route at oestrous onset and a single FTAI 16 h later; IM5FTAI - 5 mg pLH by the intramuscular route at oestrous onset and a single FTAI 16 h later. More VS2.5FTAI gilts (47.1%; p < 0.05) ovulated within 24 h after oestrous onset than control gilts (25.5%) whereas IM5FTAI gilts had an intermediate percentage (31.4%; p > 0.05). The IOEO tended to be shorter (p = 0.06) in VS2.5FTAI (30.2 ± 1.4 h) than in control (34.7 ± 1.4 h) gilts, but there was no difference (p > 0.05) between control and IM5FTAI (32.8 ± 1.4 h) gilts. Farrowing rate was not different (p > 0.05) among treatments. Total born piglets (TB) was lower (p < 0.05) in VS2.5FTAI (12.3 ± 0.4) than in control gilts (14.1 ± 0.4), whereas intermediate TB was observed in IM5FTAI gilts (13.3 ± 0.4). Due to the advancement of ovulation, reduction of the hormonal dose and the ease of application, the vulvar submucosal route would be the best option for FTAI protocols, but their negative impact on litter size remains to be elucidated. Taking into account the good fertility results obtained in IM5FTAI gilts whose ovulation was not advanced, the possibility of a single FTAI without any hormonal treatment should be further investigated, to establish reliable FTAI protocols for gilts.

Behaviour and growth performance of low-birth-weight piglets cross-fostered in multiparous sows with piglets of higher birth weights / Comportamento e desempenho de crescimento de leitões com baixo peso ao nascer uniformizados com leitões de maior peso em fêmeas suínas multíparas

The aim of the study was to evaluate the behaviour, pre-weaning survival rate and growth performance of low birth weight (BW) piglets cross-fostered with piglets of higher weights. Piglets were transferred to 60 foster sows, and divided in three groups (G; n=20): G1- 12 low BW piglets (0.80 - 1.25kg); G2- six low BW piglets and six intermediate BW piglets (1.40 - 1.60kg), and G3- six low BW piglets and six high BW piglets (>1.70kg). For the analysis, groups G2 and G3 were subdivided in LG2 (six G2 light piglets); IG2 (six G2 intermediate piglets), LG3 (six G3 light piglets), and HG3 (six G3 heavy piglets). Behavioural observations were carried out on days 1, 2, 4 and 6 (visual direct observation) and on days 3 and 5 (video recording) after birth. The percentage of missed nursings was higher in LG3 piglets than in LG1, IG2 and HG3 piglets, on days 1 and 2. On day 4, light piglets (LG1, LG2 and LG3) missed more nursings than IG2 and HG3 piglets. On day 3, video recording showed a higher percentage of missed nursings in LG1, LG2, and LG3 piglets as compared to HG3 piglets. On day 1, the number of fights during nursing was higher in IG2 than in LG1 and LG3 piglets. Also on day 1, number of fights and percentage of piglets engaged in fights, during 15min after nursing, were higher in LG1, LG3 and HG3 than in LG2 piglets. More playful behaviours were observed on day 2 in IG2 and HG3 piglets compared to LG1, LG2 and LG3 piglets. Light piglets (LG1, LG2, and LG3) presented similar body weight on days 4, 8, 12 and 16 after birth, regardless of being mixed with piglets of higher weights or not; however, the survival rate until day 16 was most compromised in LG3 piglets compared to the other groups. Despite the lack of influence of littermates' weight on the growth of low BW piglets, their survival rate indicates that they should not be mixed with high BW piglets.(AU)

O objetivo do estudo foi avaliar o comportamento, a taxa de sobrevivência pré-desmame e o desempenho de crescimento de leitões leves ao nascer uniformizados com leitões de maior peso ao nascer (PN). Os leitões foram transferidos para 60 fêmeas e divididos em três grupos (G; n=20): G1 - 12 leitões de baixo PN (0,80-1,25kg); G2 - seis leitões de baixo PN e seis com PN intermediário (1,40-1,60kg); e G3 - seis leitões de baixo PN e seis leitões pesados (>1,70kg). Para a análise, os grupos G2 e G3 foram subdivididos em LG2 (seis G2 leitões leves); IG2 (seis G2 leitões de peso intermediário); LG3 (seis G3 leitões leves) e HG3 (seis G3 leitões pesados). Observações de comportamento foram realizadas nos dias 1, 2, 4 e 6 (observações visuais diretas) e nos dias 3 e 5 (gravações) após o nascimento. A porcentagem de mamadas perdidas foi maior no grupo LG3 quando comparado aos grupos LG1, IG2 e HG3, nos dias 1 e 2. No dia 4, leitões leves (LG1, LG2 e LG3) perderam maior número de mamadas do que os grupos IG2 e HG3. No dia 3, a gravação mostrou maior porcentagem de perda de mamadas nos grupos LG1, LG2 e LG3 do que no grupo HG3. No dia 1, o número de brigas durante a mamada foi maior nos grupos IG2 do que nos grupos LG1 e LG3. Também no dia 1, o número de brigas e porcentagem de leitões envolvidos em brigas, durante 15 minutos após a mamada, foi maior nos grupos LG1, LG3 e HG3 do que no grupo LG2. Brincadeiras foram mais observadas no dia 2 nos grupos IG2 e HG3 quando comparado aos grupos LG1, LG2 e LG3. Leitões leves (LG1, LG2 e LG3) apresentaram peso semelhante nos dias 4, 8, 12 e 16 após o nascimento, independentemente de serem misturados ou não com leitões pesados. No entanto, a taxa de sobrevivência até o dia 16 foi mais comprometida nos leitões do grupo LG3 do que nos outros grupos. Apesar da falta de influência do peso das leitegadas no crescimento de leitões de baixo PN, a taxa de sobrevivência indicou que estes não devem ser misturados com leitões de maior PN.(AU)

Behaviour and growth performance of low-birth-weight piglets cross-fostered in multiparous sows with piglets of higher birth weights / Comportamento e desempenho de crescimento de leitões com baixo peso ao nascer uniformizados com leitões de maior peso em fêmeas suínas multíparas

The aim of the study was to evaluate the behaviour, pre-weaning survival rate and growth performance of low birth weight (BW) piglets cross-fostered with piglets of higher weights. Piglets were transferred to 60 foster sows, and divided in three groups (G; n=20): G1- 12 low BW piglets (0.80 - 1.25kg); G2- six low BW piglets and six intermediate BW piglets (1.40 - 1.60kg), and G3- six low BW piglets and six high BW piglets (>1.70kg). For the analysis, groups G2 and G3 were subdivided in LG2 (six G2 light piglets); IG2 (six G2 intermediate piglets), LG3 (six G3 light piglets), and HG3 (six G3 heavy piglets). Behavioural observations were carried out on days 1, 2, 4 and 6 (visual direct observation) and on days 3 and 5 (video recording) after birth. The percentage of missed nursings was higher in LG3 piglets than in LG1, IG2 and HG3 piglets, on days 1 and 2. On day 4, light piglets (LG1, LG2 and LG3) missed more nursings than IG2 and HG3 piglets. On day 3, video recording showed a higher percentage of missed nursings in LG1, LG2, and LG3 piglets as compared to HG3 piglets. On day 1, the number of fights during nursing was higher in IG2 than in LG1 and LG3 piglets. Also on day 1, number of fights and percentage of piglets engaged in fights, during 15min after nursing, were higher in LG1, LG3 and HG3 than in LG2 piglets. More playful behaviours were observed on day 2 in IG2 and HG3 piglets compared to LG1, LG2 and LG3 piglets. Light piglets (LG1, LG2, and LG3) presented similar body weight on days 4, 8, 12 and 16 after birth, regardless of being mixed with piglets of higher weights or not; however, the survival rate until day 16 was most compromised in LG3 piglets compared to the other groups. Despite the lack of influence of littermates' weight on the growth of low BW piglets, their survival rate indicates that they should not be mixed with high BW piglets...

O objetivo do estudo foi avaliar o comportamento, a taxa de sobrevivência pré-desmame e o desempenho de crescimento de leitões leves ao nascer uniformizados com leitões de maior peso ao nascer (PN). Os leitões foram transferidos para 60 fêmeas e divididos em três grupos (G; n=20): G1 - 12 leitões de baixo PN (0,80-1,25kg); G2 - seis leitões de baixo PN e seis com PN intermediário (1,40-1,60kg); e G3 - seis leitões de baixo PN e seis leitões pesados (>1,70kg). Para a análise, os grupos G2 e G3 foram subdivididos em LG2 (seis G2 leitões leves); IG2 (seis G2 leitões de peso intermediário); LG3 (seis G3 leitões leves) e HG3 (seis G3 leitões pesados). Observações de comportamento foram realizadas nos dias 1, 2, 4 e 6 (observações visuais diretas) e nos dias 3 e 5 (gravações) após o nascimento. A porcentagem de mamadas perdidas foi maior no grupo LG3 quando comparado aos grupos LG1, IG2 e HG3, nos dias 1 e 2. No dia 4, leitões leves (LG1, LG2 e LG3) perderam maior número de mamadas do que os grupos IG2 e HG3. No dia 3, a gravação mostrou maior porcentagem de perda de mamadas nos grupos LG1, LG2 e LG3 do que no grupo HG3. No dia 1, o número de brigas durante a mamada foi maior nos grupos IG2 do que nos grupos LG1 e LG3. Também no dia 1, o número de brigas e porcentagem de leitões envolvidos em brigas, durante 15 minutos após a mamada, foi maior nos grupos LG1, LG3 e HG3 do que no grupo LG2. Brincadeiras foram mais observadas no dia 2 nos grupos IG2 e HG3 quando comparado aos grupos LG1, LG2 e LG3. Leitões leves (LG1, LG2 e LG3) apresentaram peso semelhante nos dias 4, 8, 12 e 16 após o nascimento, independentemente de serem misturados ou não com leitões pesados. No entanto, a taxa de sobrevivência até o dia 16 foi mais comprometida nos leitões do grupo LG3 do que nos outros grupos. Apesar da falta de influência do peso das leitegadas no crescimento de leitões de baixo PN, a taxa de sobrevivência indicou que estes não devem ser misturados com leitões de maior PN...

Effect of birth weight and colostrum intake on mortality and performance of piglets after cross-fostering in sows of different parities.

The objective of this study was to evaluate the effect of colostrum intake on mortality and growth performance of piglets until 42 days of age, taking into account the birth weight, and parity order of sows. Colostrum intake from birth to 24h after birth was estimated in 300 piglets each from primiparous and multiparous sows. The piglets were cross-fostered in 25 primiparous and 25 multiparous sows at 25.9±0.09 h after farrowing. The concentration of serum immunoglobulin G (IgG) was determined in the sows after the end of farrowing and in the piglets before cross-fostering (24h after farrowing), at 10 and 20 days of age. For high birth weight piglets (HBW - >1.3-1.7 kg) the probability of death was low regardless of their colostrum intake. Intermediate birth weight (IBW - >1.2-1.3 kg) and low birth weight (LBW - 1.1-1.2 kg) piglets had the same probability of death compared to HBW piglets, when colostrum intake reached 200 and 250 g, respectively. The probability of low performance (<9.5 kg) was lower in HBW than in LBW and IBW piglets, regardless of colostrum intake. HBW piglets had higher weight at 14, 20, 28 and 42 days of age (P<0.05) than LBW piglets, and higher weight than IBW piglets at 28 and 42 days. Colostrum intake >250 g increased (P<0.05) the weight of piglets at 28 and 42 days of age, regardless of their birth weight. Piglets from primiparous biological dams consumed less colostrum (P<0.003) than piglets from multiparous dams, but their serum IgG concentrations at 24h after birth and their performance were similar (P>0.05). Piglets suckled by primiparous foster sows showed lower weight (P<0.05) at 20, 28 and 42 days than piglets suckled by multiparous sows. Piglets that died before 42 days of age had lower (P<0.05) birth weight, colostrum intake and serum IgG at 24 h after birth compared to surviving piglets, and lower values were also observed in piglets with low performance compared to high (>9.5 kg) performance piglets. There were no differences in serum IgG concentrations at 10 and 20 days of age (P>0.05) between high and low performance piglets. In conclusion, both colostrum intake and birth weight are important for survival and growth of suckling piglets. LBW and IBW piglets are more dependent on colostrum intake than HBW piglets to assure higher survival and better development up to 42 days of age. Piglets suckled by multiparous sows have better development than those suckled by primiparous sows.