Immunogenicity, safety and dual DIVA-like character of a recombinant candidate vaccine against neosporosis in cattle.

Neosporosis is the major infectious cause of abortion and reproductive losses in cattle worldwide; however, there are no available vaccines or drugs to control this disease. Recently, a dual (positive and negative) DIVA-like (Differentiation of Infected from Vaccinated Animals) vaccine was evaluated in a pregnant mouse model of neosporosis, showing promising immunogenic and protective results. The current report aimed to study the safety, the dose-dependent immunogenicity and the dual DIVA-like character of a recombinant subunit vaccine composed of the major surface antigen from Neospora caninum (rNcSAG1) and the carrier/adjuvant Heat shock protein 81.2 from Arabidopsis thaliana (rAtHsp81.2) in cattle. Healthy heifers were separated and assigned to experimental groups A-F and subcutaneously immunized with 2 doses of vaccine formulations 30 days apart as follows: A (n = 4): 50 µg rNcSAG1 + 150 µg rAtHsp81.2; B (n = 4): 200 µg rNcSAG1 + 600 µg rAtHsp81.2; C (n = 4): 500 µg rNcSAG1 + 1,500 µg rAtHsp81.2; D (n = 3): 150 µg rAtHsp81.2; E (n = 3):1,500 µg rAtHsp81.2, and F (n = 3) 2 ml of sterile PBS. The immunization of heifers with the different vaccine or adjuvant doses (groups A-E) was demonstrated to be safe and did not modify the mean value of the evaluated serum biomarkers of metabolic function (GOT/ASP, GPT/ALT, UREA, Glucose and total proteins). The kinetics and magnitude of the immune responses were dose-dependent. The higher dose of the vaccine formulation (group C) stimulated a broad and potent humoral and cellular immune response, characterized by an IgG1/IgG2 isotype profile and IFN-γ secretion. In addition, this was the first time that dual DIVA-like character of a vaccine against neosporosis was demonstrated, allowing us to differentiate vaccinated from infected heifers by two different DIVA compliant test approaches. These results encourage us to evaluate its protective efficacy in infected pregnant cattle in the future.

Do the blood anti-Müllerian hormone concentrations in young females correlate with the ovarian follicular population later in life in water buffalo?

In this longitudinal study, the anti-Müllerian hormone (AMH) levels in blood were determined in 32 Murrah buffalo females at 8, 10, 12, 16 and 19 months of age when females were synchronized and the antral follicular population (AFP) was estimated. Correlations of AFP to the AMH level at 19 months of age and retrospectively to younger ages were investigated. Then females were split into high and low AFP, and their AMH levels were compared for all ages and tested as predictors of AFP categories. The highest AMH level (p < .05) was detected at 8 months, reducing but not differing (p > .05) at 10, 12 and 16 months then reducing again (p < .05) at 19 months of age. The mean AFP was 17.6 ± 6.3 follicles, and it was positively correlated with AMH in all ages tested. High AFP females had approximately two times more antral follicles than low AFP (p < .05) and their AMH levels were higher (p < .01) than in low AFP ones in all ages. Only at 8 months, AMH levels can be used to precociously detect high AFP heifers (a cut-off point of 464.7 pg/mL; p < .05), while low AFP heifers could be detected by AMH measurements at 8, 10, 12 and 16 months of age (p < .05). We conclude that AMH of buffalo calves correlates with AFP of heifers later in life and depending on the age, its levels could be used to identify future females with low or high AFP.

Long-term impacts of 48-h water and feed deprivation on blood and performance responses of grazing Bos indicus Nellore heifers.

The study investigated the effects of 48-h water and feed deprivation on blood and the performance of grazing Nellore (Bos indicus) heifers. Twenty-four Nellore heifers (initial body weight [BW] = 238 ±â€…10 kg; age = 16 ±â€…2 mo), were ranked by initial BW and age and randomly assigned to one of the two treatments: (1) grazing animals with free access to pasture, water, and mineral-mix (CON; n = 12), or (2) the same grazing conditions but deprived of pasture, water, and mineral-mix for 48 h (DPR; n = 12). The paddocks consisted of Urochloa brizantha cv. Marandu, using a continuous and fixed stocking rate. The experiment lasted 225 d, with the first 14 d considered as the adaptation period (days -14 to -1) and the subsequent 211 d as the evaluation period (days 0 to 211). From days 0 to 2, treatments were applied by keeping the DPR heifers in pens and reintegrating them into the experimental area after a 48-h water and feed deprivation. Individual full BW was recorded on days -14, -13, -1, before (day 0) and after (day 2) treatment application, and on days 6, 11, 12, 41, 42, 210, and 211. Blood samples were collected in the morning on days 0, 2, 6, 12, and 211. A treatment effect was detected (P < 0.001) for shrink BW from days 0 to 2, which was greater (P < 0.001) in DPR vs. CON heifers. Subsequently, DPR animals were lighter (P < 0.001) compared with CON heifers by the end of the deprivation period (day 2). From days 4 to 211, DPR was lighter (P < 0.001) compared with CON heifers after treatment application and for the entire experimental period. In the first 10 d after treatment application (days 2 to 12), DPR heifers showed a partial compensatory average daily gain (ADG; P < 0.001) compared with CON heifers, while no significant differences were observed in ADG between the treatments from days 12 to 42 and 42 to 211 (P > 0.420). Overall ADG (days 2 to 211) was greater (P < 0.001) for DPR vs. CON heifers. All serum variables, except AST, were higher (P < 0.001) in DPR than in CON heifers on day 2 after treatment application. Our study demonstrates that grazing Nellore heifers subjected to 48-h water and feed deprivation experienced significant alterations in their blood metabolites and BW immediately after the stressful event. Although the deprived heifers partially compensated for their BW loss in the early days post-deprivation, they remained 12 kg lighter than the non-deprived animals throughout the production cycle.

Effects of breed on preferential intake of hydroxychloride and sulfate sources of trace minerals in growing beef heifers.

This study evaluated the effects of breed on voluntary preferential intake of two sources of Cu, Mn, and Zn when added to white salt-based trace mineral supplement (days 0 to 55; experiment 1) and protein supplement (days 56 to 112; experiment 2). On day 0, Nelore and ½ Angus × ½ Nelore heifers (n = 20/breed) were stratified by breed, body weight (BW = 347 ±â€…82 kg), and age (12 to 30 mo), and randomly allocated into 1 of the 40 drylot pens (1 heifer/pen). Both experiments were divided into washout (days 0 to 27 in experiment 1 and days 56 to 83 in experiment 2) and preferential intake periods (days 28 to 55 in experiment 1 and days 84 to 112 in experiment 2). During the respective preferential intake period, heifers were provided simultaneous free-choice access to sulfate (SUL) and hydroxychloride (HYD) sources of Cu, Mn, and Zn mixed into salt-based trace mineral supplements from days 28 to 55 (experiment 1) and then protein supplements from days 84 to 112 (experiment 2). Heifers were provided free-choice access to Tifton 85 (Cynodon sp.) hay from days 0 to 112. Effects of breed × source × day of the study were detected (P ≤ 0.05) for daily trace mineral intake from days 28 to 56 and days 84 to 112. Angus × Nelore heifers consumed a greater amount of SUL vs. HYD supplements on days 31 to 33 (P = 0.02) and HYD vs. SUL supplements on days 37 to 42 (P ≤ 0.02), whereas Nelore heifers consumed more HYD vs. SUL supplements on days 31 to 33 and 43 to 51 (P ≤ 0.05). Both breeds consumed (P ≤ 0.05) a greater amount of protein supplement containing HYD vs. SUL from days 84 to 112, but the differences in protein supplement intake increased (P ≤ 0.04) in greater magnitude for Nelore vs. Angus × Nelore heifers. Supplement intake coefficient of variation (CV) from days 28 to 41 and days 84 to 97 tended (P = 0.06) to be greater for Nelore vs. Angus × Nelore heifers. Effects of breed × source were detected (P = 0.02) for supplement intake CV from days 84 to 112. Intake CV of supplements added with HYD did not differ (P ≥ 0.40) between Nelore vs. Angus × Nelore heifers but was greater (P < 0.01) for Nelore vs. Angus × Nelore heifers fed SUL supplements. Overall, Nelore heifers had greater preferential intake for mineral and protein supplements containing hydroxychloride vs. sulfate sources compared to Angus × Nelore heifers. Hydroxychloride sources encouraged voluntary intake and reduced variation in supplement consumption compared to SUL sources of the same metals.

Performance, Intake, Feed Efficiency, and Carcass Characteristics of Young Nellore Heifers under Different Days on Feed in the Feedlot.

Two studies evaluated the productive characteristics of young Nellore heifers receiving different days on feed (DOF) to determine the biological slaughter endpoint. In Experiment 1 (Exp. 1), fifty-one Nellore heifers [324 ± 19.3 kg of body weight (BW); 16 ± 1 months] were split into three DOF lengths (45, 75, or 105 days), while in Experiment 2 (Exp. 2), thirty-six Nellore heifers (362 ± 25.5 kg of BW; 18 ± 1 months of age) were split into three DOF lengths (45, 90, or 135 days). In both studies, all animals were distributed in complete randomized blocks according to initial BW and stratified via carcass ultrasound. The diet was supplied ad libitum, allowing 3% of refusals. The point at which the animals achieved 25% of ether extract of shrunk body weight (EESBW) was defined as the biological endpoint. Thus, relationships were made between some characteristics obtained in both studies. Positive linear relationships were found between backfat thickness (BFT) vs. EESBW (p < 0.001, r = 0.84) and BFT vs. body weight (p < 0.001, r = 0.77). Our results suggest that the biological slaughter endpoint for young Nellore heifers is 6.97 mm of backfat thickness or 402 kg shrunk body weight, corresponding to around 75 DOF.

Tropical grass silages with spineless cactus in diets of Holstein × Zebu heifers in the semiarid region of Brazil.

One of the factors that limit ruminant production in the semiarid region is the lack of roughage in the dry season. The management of forage plants adapted to edaphoclimatic conditions is a strategy to improve animal production. This study was conducted to examine the effects of biomass sorghum silage (BSS; Sorghum bicolor (L.) Moench) and BRS capiaçu grass silage (CGS; Pennisetum purpureum Schum) with or without spineless cactus (Opuntia spp.) in crossbred Holstein × Zebu heifers' diets on the intake, apparent digestibility of the nutrients and animal performance (e.g., final weight, daily weight gain) (experiment 1). Also, to evaluate the ruminal kinetics of dry matter (DM) and neutral detergent fiber (NDF) of roughages used in diets using two animals cannulated in the rumen (experiment 2). In experiment 1, ten heifers with an initial body weight of 200 ± 2.74 kg (mean ± standard deviation) and a mean age of 10 months were used. The animals were distributed in an experimental design in two simultaneous 5 × 5 Latin squares. Five experimental diets were used: diet 1, Volumax sorghum silage (VSS); diet 2, biomass sorghum silage (BSS); diet 3, BRS capiaçu silage (CGS); diet 4, biomass sorghum silage (60%) with spineless cactus (40%) (BSS + SC); and diet 5, BRS capiaçu grass silage (60%) with spineless cactus (40%) (CGS + SC). The diets were formulated with sorghum silage or BRS capiaçu grass silage with or without spineless cactus (roughage) and a maize- and soybean-based concentrate (75:25 roughage-to-concentrate ratio) on DM basis. The experiment lasted 105 days, divided into five periods of 21 days (17 days for the adaptation of the animals to the diets and management and 4 for data collection and samples). The diets containing CGS and CGS + SC resulted in lower dry matter intake (DMI; 5.61 kg day-1; P < 0.01), which was 19.4% lower than the diets with VSS, BSS, and BSS + SC (7.00 kg day-1). The BSS + SC and CGS + SC diets showed higher crude protein digestibility (P < 0.01) at 21.9% than the other treatments (Volumax, BSS, CGS). The different diets did not change the final weight or the daily weight gain of the heifers. The BRS 716 biomass sorghum silage and BRS capiaçu grass combined with spineless cactus increased (P < 0.05) the intake of nonfibrous carbohydrates and did not interfere (P > 0.05) with the final weight or average daily gain of the crossbred Holstein × Zebu heifers. The standardized potentially degradable fraction (Bp) of the NDF was 13.91% higher (P < 0.01) for BSS and BSS + SC (61.6%) compared to the others (53.0%). A diet based on BSS + SC is recommended for feeding crossbred heifers in the growing phase.

The influence of weaning age and biocholine supplementation to post-weaning growth and puberty in Brangus heifers.

This experiment was conducted to determine the effect of earlier weaning in addition to biocholine supplementation on age at puberty of Brangus heifers. Brangus calves were randomized and divided into three weaning ages groups, at 30 (Hyper-early weaning; HW), 75 (Early weaning; EW) and 180 days (Conventional weaning; CW). Then, calves were supplemented using the additive Biocholine (BIO) or not (CON). Animals were subjected to puberty induction and the presence of estrus was observed for 7 days. In addition, transrectal ultrasonography was performed to assess the ovarian activity and the presence of corpus luteum to determine heifer puberty. We also evaluated the body weight (BW; Kg), hip height (HH; cm), thoracic perimeter (TP; cm) and BW:HH ratio during the experimental period. BIO group showed higher ADG (>226 g/day) when the animals were exposed to ryegrass pasture compared to CON (P < 0.05). We observed an interaction between weaning x biocholine and CW-BIO heifers showed greater HH more compared to CW-CON (P < 0.05). Overall, animals that have reached puberty at day 8 after puberty induction showed 331.0 ± 5.04 kg BW, 122.0 ± 0.56 cm HH and 165.4 ± 0.75 cm TP and 2.7 ± 0.03 BW:HH. At the time of ovulation detection, the heifers from the HW group had 32.1 kg BW, 3.93 cm HH and 0.18 cm BW:HH greater compared to CW (P < 0.05). The BIO supplementation together with ryegrass pasture, led to an increase in ADG weight throughout the evaluated period. We concluded that HW heifers showed an adequate body development throughout the experimental period until puberty appearance at the same age as others weaned groups.

Antral follicle count, productive and reproductive parameters in Bos indicus and Bos indicus-taurus prepubertal heifers with early puberty induction / Contagem de folículos antrais, parâmetros produtivos e reprodutivos em novilhas pré-púberes Bos indicus e Bos indicus-taurus com indução precoce de puberdade

Prepubertal Nelore (G-N = 15) and crossbred Nelore x Aberdeen Angus heifers (G-NA = 15) were used for this study. AFC, live weight, body condition score (BCS), ovary and dominant follicle (DF) diameters were determined in each animal. Puberty induction was performed by insertion of a 4th use progesterone device (D0) which was removed on D12. Also, 1 mg estradiol benzoate was administered, and estrus intensity was classified (D12). At D21, the presence and diameter of the corpus luteum (CL) were registered. AFC was highly repeatable, regardless of hormone induction in both G-N (r=0.79) and G-NA (r=0.90). The mean AFC was greater in G-N compared to G-NA (24.2±8.5 vs. 17.7±9.0 follicles). A variation in BCS throughout the study occurred in G-NA, but not in G-N. The average weight gain (AWG) was greater in G-NA compared to G-N (0.69±0.33 vs. 0.40±0.29kg/day). The G-NA resulted in a larger diameter of DF at D12 than G-N (11.6±2.7 vs. 9.3±1.5mm). In conclusion, AFC was greater in Nelore heifers, although in both breeds this count was highly repeatable during puberty induction. Crossbred heifers had greater BCS and AWG with greater diameter of DF, indicating higher precocity when compared to Nelore heifers.

Novilhas pré-púberes Nelore (G-N=15) e mestiças Nelore x Aberdeen Angus (G-NA=15) foram utilizadas neste estudo. CFA, peso vivo, escore de condição corporal (ECC), diâmetros do ovário e folículo dominante (FD) foram determinados em cada animal. A indução da puberdade foi realizada pela inserção de um dispositivo de progesterona de quarto uso (D0), que foi retirado no D12. Além disso, 1mg de benzoato de estradiol foi administrado e a intensidade do estro foi classificada (D12). No D21, foram registrados a presença e o diâmetro do corpo lúteo (CL). A CFA foi altamente repetível, independentemente da indução hormonal em G-N (r=0,79) e G-NA (r=0,90). A CFA média foi maior em G-N em comparação com G-NA (24,2±8,5 vs. 17,7±9,0 folículos). Uma variação no ECC ao longo do estudo ocorreu em G-NA, mas não em G-N. O ganho de peso médio (GPM) foi maior em G-NA em comparação com G-N (0,69±0,33 vs. 0,40±0,29kg/dia). O G-NA resultou em um diâmetro maior de FD em D12 do que o G-N (11,6±2,7 vs. 9,3±1,5mm). Em conclusão, a CFA foi maior em novilhas Nelore, embora em ambas as raças essa contagem tenha sido altamente repetível durante a indução da puberdade. Novilhas mestiças apresentaram maior ECC e GPM com maior diâmetro de FD, indicando maior precocidade quando comparadas às novilhas Nelore.

Performance and feeding behavior of Holstein and Holstein × Gyr crossbred heifers grazing temperate forages.

This study aimed to investigate the difference between Holstein and Holstein × Gyr breeds on feeding behavior and performance of heifers grazing temperate pasture. The experiment was carried out in 89 days, split into 14 days of adaptation, and 3 periods of 25 days. Two treatments were used: Holstein (HOL; n = 7) and Holstein × Gyr (HG; n = 7). Heifers grazed a consortium of ryegrass and bristle oats and were supplemented individually daily with cornmeal at 0.33% of body weight plus 5 kg/day of corn silage. For 3 consecutive days, feeding behavior was observed for individual animals from direct visual observation recording at 10-min intervals. The digestibility trial was performed on day (d) 16 to d24 of each period. Body measurements and weight were taken at d0 and at d23, 24, and 25 of each period. Grazing duration, grazing frequency, and bite rate were greater for HOL than those for HG. Rumination characteristics, intake, digestibility, and body measurements were not affected by breed. Breeds had differences in grazing characteristics, but they did not influence performance or intake parameters. Therefore, HOL and HG heifers managed under temperate pasture in tropical countries have similar performances.

Does a high or moderate nutritional supplementation affect the puberty and productive performance of Nellore heifers?

The effects of higher supplementation levels for young Nellore heifers fed tropical forages including their influence on puberty, need to be understood. This study investigated the influence of high and moderate supplementation levels on puberty onset and the productive performance of Nellore heifers. Thirty-six Nellore heifers (225 + 3.52 kg) were used in a completely randomized design, with three treatments: (I) no concentrate (control); (II) concentrate supplement at 4 g/kg body weight (BW); (III) concentrate supplement at 8 g/kg BW. Increased supplement level led to a linear increase in average daily gain (P < 0.05). The high supplementation level (8 g/kg BW) had the highest proportion of corpus luteum presence (82% of heifers), compared to the 4 g/kg BW treatment group (67%) and the control group (33%; P < 0.05). Our findings indicate that providing a high level of energy supplementation to Nellore heifers for approximately 100 d improves performance and increases the proportion of heifers that reach puberty.

Relationships between antral follicle counts and ovarian morphology of Bos indicus of different ages / Relações entre a contagem de folículos antrais e a morfologia ovariana de Bos indicus de diferentes idades

This study aimed to evaluate the relationship between the antral follicle count (AFC) and the ovarian morphology of Bos indicus in different age groups: 12-23 months (G1), 24-35 months (G2), 36-47 months (G3), 48-59 months (G4), and >60 months (G5). Ovaries were collected individually and sent to the laboratory, where we measured AFC, the diameter and weight of the ovaries, dominant follicle (DF, >8mm), corpus luteum (CL), and small follicles (SF, <8mm). AFC were classified as high, intermediate-high, intermediate-low, and low. A group of ovaries was subjected to follicular aspiration to evaluate the morphological quality of the recovered cumulus oocyte complexes (COCs). Mean AFC did not vary between ages. The morphological characteristic that was most closely correlated with AFC was the weight of the small follicles. There was no relationship between AFC and the weight and diameter of the DF and CL. Quality of the COCs was superior in ovaries in which the CL was present, but it did not vary between the AFC classes. We conclude that AFC can be performed on a single ovary, regardless of the presence, diameter, and weight of the CL and DF in zebu between 12 and 60 months old.

O presente estudo teve como objetivo avaliar a relação entre a contagem de folículos antrais (CFA) e a morfologia ovariana de Bos indicus em diferentes faixas etárias: 12-23 meses (G1), 24-35 meses (G2), 36-47 meses (G3), 48-59 meses (G4) e >60 meses (G5). Os ovários foram coletados individualmente e enviados ao laboratório, onde suas características morfológicas foram medidas: CFA, diâmetro e peso dos ovários, do folículo dominante (FD, ≥8 mm), do corpo lúteo (CL) e dos folículos pequenos (SF, <8 mm). A CFA foi classificada como alta, intermediária-alta, intermediária-baixa e baixa. Um grupo de ovários foi submetido à aspiração folicular para avaliar a qualidade morfológica dos complexos cumulus oócitos (COCs) recuperados. A CFA média não variou entre as idades. A característica morfológica que se correlacionou mais intimamente com a CFA foi o peso dos folículos pequenos. Não houve relação entre a CFA e o peso e o diâmetro do FD e do CL. A qualidade dos COCs foi superior em ovários em que o CL estava presente, mas não variou entre as classes de CFA. Concluiu-se que a CFA pode ser realizada em um único ovário, independentemente da presença, do diâmetro e do peso do CL e do FD em zebuínos entre 12 e 60 meses de vida.

Prediction of live weight in beef heifers using a body volume formula / Predição do peso vivo em novilhas de corte usando a fórmula do volume corporal

The objective of this study was to develop and evaluate linear, quadratic, and allometric models to predict live weight (LW) using the body volume formula (BV) in crossbred heifers raised in southeastern Mexico. The LW (426.25±117.49kg) and BV (338.05±95.38 dm³) were measured in 360 heifers aged between 3 and 30 months. Linear and non-linear regression were used to construct prediction models. The goodness-of-fit of the models was evaluated using the Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), coefficient of determination (R²), mean squared error (MSE), and root MSE (RMSE). In addition, the developed models were evaluated through cross-validation (k-folds). The ability of the fitted models to predict the observed values was evaluated based on the RMSEP, R² and mean absolute error (MAE). The quadratic model had the lowest values of AIC (2688.39) and BIC (2700.05). On the other hand, the linear model showed the lowest values of MSE (7954.74) and RMSE (89.19), and the highest values of AIC (2709.70) and BIC (2717.51). Despite this, all models presented the same R² value (0.87). The cross-validation (k-folds) evaluation of fit showed that the quadratic model had better values of MSEP (41.49), R2 (0.85), and MAE (31.95). We recommend the quadratic model to predictive of the crossbred beef heifers' live weight using the body volume as the predictor.

O objetivo deste estudo foi desenvolver e avaliar os modelos linear, quadrático e alométrico para predizer o peso vivo (PV), usando-se a fórmula do volume corporal (VC) em novilhas mestiças criadas no sudeste do México. O PV (426,25+117,49kg) e o VC (338,05±95,38dm³) foram medidos em 360 novilhas, com idade entre três e 30 meses. Regressões lineares e não lineares foram utilizadas para construir os modelos de predição. A adequação dos modelos foi avaliada utilizando-se o critério de informação de Akaike (AIC), o critério de informação bayesiano (BIC), o coeficiente de determinação (R), o quadrado médio do erro (QME) e a raiz do QME (ROME). Além disso, os modelos desenvolvidos foram avaliados por meio de validação cruzada (k-folds). A capacidade dos modelos ajustados em prever os valores observados foi avaliada com base no ROME, no R² e no erro médio absoluto (EMA). O modelo quadrático apresentou os menores valores de AIC (2688,39) e de BIC (2700,05). Por outro lado, o modelo linear apresentou os menores valores de QME (7954,74) e de ROME (89,19); esse modelo apresentou os maiores valores de AIC (2709,70) e de BIC (2717,51). Apesar disso, todos os modelos apresentaram o mesmo valor para o R (0,87). A avaliação de ajuste por validação cruzada (k-folds) mostrou que o modelo quadrático teve melhores valores de ROME (41,49), R² (0,85) e EMA (31,95). Recomenda-se o modelo quadrático para predição do peso vivo de novilhas de corte mestiças utilizando-se o volume corporal como preditor.

Effect of ovarian status on reproductive performance in dairy heifers inseminated with sexed semen

Background: The intensive reproductive management in the dairy farms requires inclusion of a large group of replacement heifers in the breeding program for a shorter period. In this aspect, a creation of effective estrus synchronization protocols with timed artificial insemination (TAI) by sexed semen and optimization of the current ones have a crucial role for obtaining high pregnancy rate. These protocols are beneficial, because they led to reduced interval to first AI, lack of need for estrus detection, and allow obtaining a large group of female calves for on time. Because of limited fertilizing potential of sexed spermatozoa this type of semen is applied mainly for heifers, as fertility is higher compared to lactating cows. The main objective of the present study was to investigate the effect of ovarian status on the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Materials, Methods & Results: Forty-eight Holstein healthy heifers separated in 2 groups were subjected to PGF2α-GnRH pre-treatment and Ovsynch or PRID-5-day estrus synchronization protocol and timed artificial insemination (TAI) with sex-sorted semen, staring 6 days after end of the hormonal pre-treatment. The ovarian status (presence of follicles with or not a corpus luteum) of the heifers at the begin of the treatment, on day of TAI and pregnancy rate in different groups were determined and compared. Additionally, the ovarian status at the begin of the treatment, ovarian status and size of preovulatory follicle (PF) on day of TAI and total values for both groups according to reproductive performance (pregnant or non-pregnant) were also analyzed. On day of TAI the animals with PF and a lack of corpus luteum (CL) in both groups were more that those with PF and CL (39.3% and 30% vs. 60.7 % and 70%), with significant (P < 0.05) difference in PRID-5-day group. The pregnancy rate tended to be higher in PRID-5 day than Ovsynch treatment (65% vs. 35.7%). A higher percentage (100% and 67.9%) of the pregnant animals in both treatments had not CL on day of TAI, and the size of the PF (1.58 ± 0.12 cm and 1.64 ± 0.13 cm) was increased (P < 0.05). Similar effects of the ovarian status on reproductive performance were obtained after a comparison of the total values between pregnant and non-pregnant animals. The percentage of heifers with observed PF without CL on day of TAI was significantly greater (P < 0.05) in pregnant compared to non-pregnant group (91.3% vs. 40%). The opposite dependence was determined for the parameter presence of follicles and corpus luteum (8.7% vs. 60%; P < 0.05). Furthermore, the size of the PF measured immediately before TAI was increased in animals became pregnant (1.60 ± 0.12 cm vs. 1.34 ± 0.17 cm; P < 0.05). Discussion: The analysis of the obtained results showed that the ovarian status on day of TAI affects the reproductive performance in dairy heifers subjected to estrus synchronization and timed artificial insemination with sexed semen. Hormonal pre-treatment with onset of PRID-5-day protocol 6 days later and TAI with sex-sorted semen ensure acceptable pregnancy rate. The greater preovulatory follicle and a lack of corpus luteum before insemination provide significantly (P < 0.05) more pregnant animals, compared to the cases when CL is presented. Ultrasound determination of the ovarian function before insemination can be used in selection of heifers for TAI with sex-sorted semen.

Feed Intake of Growing Dairy Heifers Raised under Tropical Conditions: A Model Evaluation Using Meta-Analysis.

Several models for predicting dry matter intake (DMI) of replacement dairy heifers have been developed; however, only a few have been evaluated using data from heifers of different breeds raised under tropical conditions. Thus, the objective of this study was to evaluate the DMI equations for dairy heifers managed under tropical conditions. A total of 230 treatment means from 61 studies using dairy heifers (n = 1513 heifers, average body weight = 246 kg) were used. The animals were grouped into two groups based on their genetics: (1) Bos taurus (Holstein, Jersey, Brown Swiss, and Holstein × Jersey) and (2) crossbred (Bos taurus × Bos indicus). Seven previously published DMI equations (HH, HHJ, QUI, STA, 2001 NRC, OFLin, and OFNLin) for heifers were evaluated using mean bias, slope bias, mean squared prediction errors (MSPE) and its decomposition, and other model evaluation statistics. For Bos taurus heifers, our results indicated that OFNLin and HHJ had lower mean bias (0.13 and 0.16 kg/d, respectively) than other models. There was no significant slope or mean bias for HHJ and OFNLin (p > 0.05), indicating agreement between the observed and predicted DMI values. All other models had a significant mean bias (p < 0.05), whereas the QUI model also presented a significant slope bias (p < 0.02). For crossbred heifers, the STA equation was the only one that did not present mean and slope bias significance (p > 0.05). All other DMI models had significant mean bias when evaluated using crossbred data (p < 0.04), and QUI, OFLin, and OFNLin also presented significant slope bias (p < 0.01). Based on our results, predictions from OFNLin and HHJ best represented the observed DMI of Bos taurus heifers (MSPE ≤ 1.25 kg2/d2, mean bias ≤ 0.16 kg/d), whereas STA was the best model for crossbred heifers (MSPE = 1.25 kg2/d2, mean bias = 0.09 kg/d). These findings indicate that not all available models are adequate for estimating the DMI of dairy heifers managed under a tropical climate, with HHJ and OFNLin for Bos taurus and STA for crossbreds being the most suitable models for DMI prediction. There is evidence that models from Bos taurus heifers could be used to estimate the DMI of heifers under tropical conditions. For heifer ration formulation is necessary to consider that DMI is influenced by breed, diet, management, and climate. Future work should also include animal genetic and environmental variables for the prediction of DMI in dairy heifers.

Effects of Transportation Stress on Complete Blood Count, Blood Chemistry, and Cytokine Gene Expression in Heifers.

Blood samples were obtained from 16 high-risk heifers; eight were newly arrived from a 40 h road trip (0 days post-arrival (DPA)), whereas the other eight heifers had been in the feedlot at 25 DPA. Both groups were transported from the southeast tropical region of Mexico to a feedlot in the northeast and were sampled on the same day. The complete blood count, blood chemistry, and cytokine gene expression were analyzed. Gene expression was analyzed using specific primers to amplify and quantify the cDNA reverse transcribed from the mRNA transcripts for tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL)-2. Higher values for hematocrit (p = 0.029), hemoglobin (p = 0.002), eosinophils (0.029), albumin (p = 0.014), alanine aminotransferase (p = 0.004), bilirubin (p = 0.003), cholesterol (p = 0.014), and cortisol (p = 0.051) were observed in the 0 DPA group than the 25 DPA group. In the electrophoresis of TNF-α amplification products, two non-specific bands were observed in the 0 DPA group. These bands were sequenced, and BLAST analysis suggested that they corresponded to bovine lymphotoxin and have not been reported previously related to stress. The TNF-α expression level was higher (p = 0.001) in the 25 DPA group than the 0 DPA group according to the semi-quantitative expression analysis. This may indicate a persistent inflammatory process that could be related to trauma and disease, which can negatively impact their subsequent health and growth performance. In conclusion, homeostatic disruption was apparent in the 0 DPA heifers, which showed higher cortisol and reductions in TNF-α levels and stress-induced bovine lymphotoxin (SIBL) co-expression.

Predatory activity of nematophagus fungus Duddingtonia flagrans in infective larvae after gastrointestinal transit: biological control in pasture areas and in vitro.

Biological control is a strategy to decrease parasitic populations, and the action takes place through natural antagonists in the environment. We studied the predatory activity of the fungus Duddingtonia flagrans in infective larvae (L3) of gastrointestinal nematodes after gastrointestinal transit. Ten heifers were divided into two groups: treated (animals received pellets containing fungus) and control (animals received pellets without fungus). Twelve hours after administration, faeces samples were collected for in vitro efficacy tests. The animals then remained for 7 h in the experimental pasture area. At the end of this period, 20 faecal pads (ten treated and ten control) were selected at random. Pasture, faecal pad and soil collections occurred with an interval of 7 days, totalling four assessments. In vitro activity demonstrated that fungi effectively preyed on L3, achieving a reduction percentage of 88%. In the faecal pad of the pasture area, there was a difference (P < 0.05) between collections 3 and 4 for both groups; in the treated group a reduction of 65% was obtained, while in the control group there was an increase of 217% in the number of L3. The recovery of L3 in the soil and in the pasture was similar in both groups. There was no influence (P = 0.87) of the passage time on the fungus predatory activity. Duddingtonia flagrans demonstrated the ability to survive gastrointestinal transit in the animals, reducing the number of L3 in the faeces, indicating that this biological control has great potential in the control of worm infections.

Effects of protein source and lipid supplementation on conservation and feed value of total mixed ration silages for finishing beef cattle.

The objective of this study was to examine the conservation process and feed value of total mixed ration (TMR) silages. In exp. 1, we evaluated the fermentation pattern and aerobic stability of TMR silages containing different protein and lipid supplementations. In exp. 2, we compared the performance of finishing beef heifers fed those TMR silages. In both experiments, treatments were as follows: ensiled TMR with urea (U); ensiled TMR without a protein supplement at ensiling, but soybean meal supplemented at feeding to balance diet crude protein (CP) in exp. 2 (SMnf; where the acronym nf indicates nonfermented); ensiled TMR with soybean meal (SM); and ensiled TMR with rolled soybean grain (SG). Thirty-two Nellore heifers (313 ± 8.8 kg shrunk body weight [SBW]) were blocked by initial SBW, housed in individual pens, and enrolled in exp. 2 for 82 d. In exp. 1, treatment without a protein supplement (SMnf) had a lower content of CP, soluble CP, NH3-N, pH, and Clostridium count compared with U (P ≤ 0.03). Lactic acid concentrations tended to be reduced for SMnf compared with U (P = 0.09). Ethanol concentration was reduced in SG compared with SM (P < 0.01). 1,2-Propanediol concentration was increased in SMnf compared with U (P < 0.01), reduced in SM compared with SMnf (P = 0.02), and increased in SG compared with SM (P = 0.02). Dry matter (DM) loss during fermentation was low and similar among treatments (~3.7%). All silages remained stable during 10 d of aerobic exposure after feed out. Considering fermentation traits, such as pH (≤4.72), NH3-N (<10% of N, except for U treatment), butyric acid (<0.05 % DM), and DM losses (<3.70% DM), all silages can be considered well conserved. In exp. 2, diets were isonitrogenous because soybean meal was added to SMnf before feeding. Compared with SM, cattle fed SG made more meals per day (P = 0.04) and tended to have a decreased intermeal interval (P = 0.09). DM intake, average daily gain, final SBW, hot carcass weight, Biceps femoris fat thickness, and serum levels of triglycerides and cholesterol were increased for SG compared with SM (P ≤ 0.05). In brief, TMR silages exhibited an adequate fermentation pattern and high aerobic stability. The supplementation of true protein did not improve animal performance, whereas the addition of soybean grain as a lipid source improved the performance of finishing cattle fed TMR silages.

Progesterone dose during synchronization treatment alters luteinizing hormone receptor and steroidogenic enzyme mRNA abundances in granulosa cells of Nellore heifers.

The objective was to investigate effects of progesterone (P4) dose on abundance of luteinizing hormone receptor (LHCGR), aromatase (CYP19A1), 3ß-hydroxysteroid dehydrogenase (HSD3B1), and other steroidogenic mRNA transcripts in granulosa cells from dominant follicles. Nellore heifers were assigned to one of six groups: new, first-use controlled internal drug release device (CIDR1) inserted for 5 days (Large-P4-dose-D5; n = 7) or 6 days (Large-P4-dose-D6; n = 8), prostaglandin (PG)F2α administered on D0 and 1 previously-used CIDR (CIDR3) inserted for 5 days (Small- P4-dose-D5; n = 8) or 6 days (Small-P4-dose-D6; n = 8), CIDR1 inserted on D0 and removed plus PGF2α on D5 (Large-P4-dose-proestrus (PE); n = 7), and CIDR3 and PGF2α on D0 and 1, CIDR3 removed plus PGF2α on D5 (Small-P4-dose-PE; n = 7). Duration of P4 treatment (D5 compared to D6) affected abundances of CYP19A1 mRNA transcripts, with there being greater abundances on D6 than D5 (P ≤ 0.05). Heifers treated with the large dose of P4 had a smaller dominant follicle, less serum and intra-follicular estradiol (E2) concentrations (P ≤ 0.05) and lesser LHCGR, CYP19A1, and HSD3B1 transcript abundances (P ≤ 0.05). Heifers treated to induce PE had a larger follicle diameter (P = 0.09), greater intra-follicular E2 concentrations and larger abundances of CYP19A1 mRNA transcript (P ≤ 0.05) than heifers of the D6 group. Overall, treatment with larger doses of P4 resulted in lesser abundances of LHCGR, HSD3B1, and CYP19A1 mRNA transcripts; thus, potentially leading to development of smaller dominant follicles and lesser E2 concentrations.

Mineral composition and microstructure of the abaxial hoof wall in dairy heifers after biotin supplementation.

The aim of this study was to evaluate the effect of daily biotin supplementation on the mineral composition and microstructure of the abaxial hoof wall in dairy heifers. The heifers were housed on a concrete floor and fed for weight gain more than 800 g per day, which is a challenging environment for the hoof. Twelve crossbred dairy heifers (Jersey × Holstein) were divided into two treatment groups. Animals in the control group (n = 6) received a diet without supplemental biotin, while the heifers in the biotin-supplemented feed group (n = 6) each received 20 mg of biotin daily for 120 days. Samples of the abaxial hoof wall were collected from the outer claw of the fore and hind limb, before and after supplementation. The samples were evaluated by X-ray fluorescence spectrometry, computed microtomography, atomic force microscopy and confocal laser scanning microscopy. Biotin supplementation increased the sulphur content and decreased the calcium and potassium content in the abaxial hoof wall. Biotin treatment also increased the percentage of horn tubules with smaller diameter marrow (17-51 µm). However, biotin did not influence the surface relief of the hoof wall, suggesting that its action is limited to the inner layers of the stratum corneum. Daily supplementation with 20 mg of biotin promoted changes in the mineral composition and microstructure of abaxial hoof wall of crossbred dairy heifers. These findings suggest biotin supplementation improves hoof quality and may help to understand the function of biotin in the stratum corneum.

Nutritional management and sexual condition in cattle determine differentiation in the fatty acid profile of meat / Práticas nutricionais e condição sexual em bovinos determinam diferenciação no perfil de ácidos graxos da carne

This study aimed at evaluating the fatty acid profile of meat from feedlot finished heifers and steers fed with high-grain diets. It was used 45 Charolais and Nellore crossbred cattle, 21 of them were heifers with an initial age of 32 ± 2 months and 359.9 ± 6.7 kg of body weight, and 24 were steers with an initial age of 20 ± 2 months and 337.6 ± 6.2 kg of body weight. The animals were distributed in the treatments according to the energy source used in the diet, being them: rice, white oats or corn, using seven heifers and eight steers for each diet. The experimental design was completely randomized, with factorial arrangement 3 x 2 (three treatments and two sexual conditions). The diet based on corn provided higher levels of pentadecylic and margaric fatty acids. Excepting elaidic fatty acid, beef from steers and heifers was similar for the different saturated and monounsaturated fatty acids evaluated. A rice-based diet is advantageous when meat production is recommended with greater participation of fatty acids from the omega-3 group. When finished in feedlot with high-grain diets, the heifers produce meat with higher conjugated linoleic acid (CLA) content and a better ratio between omega-6/omega-3 fatty acids compared to steers. These findings indicate that it is possible to modify undesirable characteristics in meat through the nutritional management of animals, searching for a product that meets the requirements of a modern population, which is redefining its principles regarding food.(AU)

O presente estudo objetivou avaliar o perfil de ácidos graxos da carne de novilhos e novilhas, terminados em confinamento e alimentados com dietas de alto grão. Utilizaram-se 45 bovinos, sendo 21 novilhas com idade inicial de 32 ± 2 meses e 359,9 ± 6,7 kg, e 24 novilhos com idade inicial de 20 ± 2 meses e 337,6 ± 6,2 kg, oriundos do cruzamento entre as raças Charolês e Nelore. Os animais foram distribuídos nos tratamentos conforme a fonte energética utilizada na dieta, sendo essas: arroz; aveia branca ou milho, sendo utilizados sete novilhas e oito novilhos para cada dieta alimentar. O delineamento experimental foi o inteiramente casualizado, com arranjo fatorial 3 x 2 (três tratamentos e duas condições sexuais). A dieta a base de milho proporcionou maiores teores de ácidos graxos pentadecílico e margárico. A exceção do ácido graxo elaídico, a carne de novilhos e novilhas foi similar para os distintos ácidos graxos saturados e monoinsaturados avaliados. A dieta a base de grão de arroz mostra-se vantajosa quando se preconiza a produção de carne com maior participação de ácidos graxos do grupo ômega 3. As novilhas, quando terminadas em confinamento com dietas de alto grão, produzem carne com maior teor de ácido linoleico conjugado (CLA) e melhor relação entre ácidos graxos ômega 6/ ômega 3 comparadas aos novilhos. Essas constatações indicam que é possível modificar as características indesejáveis da carne a partir do manejo nutricional dos animais, na busca por um produto que atenda as exigências da população moderna, que está redefinindo os seus princípios com relação a alimentação.(AU)