Effects of weaning strategies on health, hematology, and productivity in Holstein dairy calves.

Weaning strategies in dairy calves vary considerably, though the effect on animal health is unclear. This study examined the effects of calf weaning age (6 vs. 8 wk) and pace (abrupt vs. gradual) on performance, blood, and health parameters in dairy calves. The experiment consisted of a 2 × 2 factorial arrangement of treatments, where the factors included weaning age (early vs. late) and weaning pace (abrupt vs. gradual). Holstein calves (n = 72), blocked by sex and birth weight, were randomly assigned to one of 4 treatments (n = 18 per treatment): early-abrupt (EA), early-gradual (EG), late-abrupt (LA), and late-gradual (LG). Milk replacer (24% crude protein, 17% fat; up to 1,200 g/d) was fed twice daily; water, calf starter (18% crude protein), and chopped alfalfa hay were fed ad libitum. Daily intakes of milk replacer, calf starter, and forage were recorded from birth until end of weaning. Body weight, selected health measures, blood hematology, and fecal scores were obtained 1 d preweaning and 1 d postweaning. Calves were orally bolused with a rumen pH logger for the last 3 d of the weaning transition and rumen pH was measured continuously. Data were analyzed with age, pace, age × pace interaction, birthweight, and sex as fixed effects, and starting date as a random effect. Greater age at weaning increased respiration, whereas gradual-weaned calves had lower respiration rate. Heart rate was lower in gradual than in abrupt weaned groups. Fecal score had a marginal increase in late-weaned groups and significantly increased in gradually weaned groups. No difference was detected in body core temperature by age, pace, or interaction. During the weaning transition, average daily gain was lower in LA than EA and gradually weaned groups had an increased average daily gain. Change in grain intake, but not forage intake, was greater in gradually weaned groups. Mean rumen pH marginally increased from EG to LG and from LA to LG. No difference was detected among treatments in red or white blood cell counts, and hemoglobin. Procalcitonin was marginally highest in the LA group, while blood hematocrit increased in abruptly weaned groups. Overall, calf health is affected by both age and pace of weaning, though the health parameters affected by age and pace differ.

Evaluating oral swab samples for PRRSV surveillance in weaning-age pigs under field conditions.

Introduction: The use of serum and family oral fluids for porcine reproductive and respiratory syndrome virus (PRRSV) surveillance in weaning-age pigs has been previously characterized. Characterizing more sample types similarly offers veterinarians and producers additional validated sample options for PRRSV surveillance in this subpopulation of pigs. Oral swab sampling is relatively easy and convenient; however, there is sparse information on how it compares to the reference sample type for PRRSV surveillance under field conditions. Therefore, this study's objective was to compare the PRRSV reverse-transcription real-time polymerase chain reaction (RT-rtPCR) test outcomes of oral swabs (OS) and sera samples obtained from weaning-age pig litters. Method: At an eligible breeding herd, six hundred twenty-three weaning-age piglets from 51 litters were each sampled for serum and OS and tested for PRRSV RNA by RT-rtPCR. Results and Discussion: PRRSV RT-rtPCR positivity rate was higher in serum samples (24 of 51 litters, 83 of 623 pigs, with a mean cycle threshold (Ct) value of RT-rtPCR-positive samples per litter ranging from 18.9 to 32.0) compared to OS samples (15 of 51 litters, 33 of 623 pigs, with a mean Ct of RT-rtPCR positive samples per litter ranging from 28.2 to 36.9); this highlights the importance of interpreting negative RT-rtPCR results from OS samples with caution. Every litter with a positive PRRSV RT-rtPCR OS had at least one viremic piglet, highlighting the authenticity of positive PRRSV RT-rtPCR tests using OS; in other words, there was no evidence of environmental PRRSV RNA being detected in OS. Cohen's kappa analysis (Ck = 0.638) indicated a substantial agreement between both sample types for identifying the true PRRSV status of weaning-age pigs.

The effect of weaning age on animal performance in lambs exposed to naturally acquired nematode infections.

The effects of mixed gastrointestinal nematode (GIN) infections on animal growth and post-weaning activity patterns were investigated in grazing intact ram lambs when naturally exposed to two different infection levels and weaned at different ages. Ewes and their twin-born lambs were turned-out to graze in two permanent pasture enclosures naturally contaminated with GIN the previous year. Ewes and lambs in the low parasite exposure group (LP) were drenched before turn-out and at weaning, respectively, with 0.2 mg ivermectin per kg body weight, whereas those in the high parasite exposure group (HP) were left untreated. Two weaning ages were applied, early weaning (EW) (10 weeks) and late weaning (LW) (14 weeks), respectively. The lambs were then allocated to one out of four groups based on parasite exposure level and weaning age (EW-HP, n = 12; LW-HP, n = 11; EW-LP, n = 13; LW-LP, n = 13). Body weight gain (BWG) and faecal egg counts (FEC) were monitored, in all groups, from the day of early weaning and every four weeks, for 10 weeks. In addition, nematode composition was determined using droplet digital PCR. Activity patterns measured as Motion Index (MI; the absolute value of the 3D acceleration) and lying time were monitored continuously from the day of weaning until four weeks post-weaning using IceQube® sensors. Statistical analyses were performed in RStudio, using mixed models with repeated measures. BWG was 11% lower in EW-HP compared with EW-LP (P = 0.0079) and 12% lower compared with LW-HP (P = 0.018), respectively. In contrast, no difference in BWG was observed between LW-HP and LW-LP (P = 0.97). The average EPG was higher in EW-HP compared with EW-LP (P < 0.001), as well as in EW-HP compared with LW-HP (P = 0.021), and LW-HP compared with LW-LP (P = 0.0022). The molecular investigation showed that animals in LW-HP had a higher proportion of Haemonchus contortus compared with EW-HP. MI was 19% lower in EW-HP compared with EW-LP (P = 0.0004). Daily lying time was 15% shorter in EW-HP compared with EW-LP (P = 0.0070). In contrast, no difference in MI (P = 0.13) and lying time (P = 0.99) between LW-HP and LW-LP was observed. The results suggest that a delayed weaning age may reduce the adverse effects of GIN infection on BWG. Contrarily, an earlier weaning age may reduce the risk of H. contortus infection in lambs. Moreover, the results demonstrates a potential use of automated behaviour recordings as a diagnostic tool for the detection of nematode infections in sheep.

A field trial on the effect of cross-fostering and weaning age on daily gain and disease resilience in weaned pigs.

Alternative management strategies that can increase disease resilience and reduce antibiotics in weaned pigs are needed. Our objective was to compare the effect of two nursing strategies and weaning ages on weight gain, clinical health and antibiotic treatments in weaned pigs not provided with medical zinc oxide in feed. A 2×2 factorial trial was conducted in three Danish commercial herds. Nursing strategies tested were "cross-fostering allowed" (CF) vs. "cross-fostering not allowed" (non-CF). Weaning ages tested were four (24-29 days) vs. five weeks (31-35 days). Pigs were followed from weaning until 33-35 days post-weaning. Herd staff made decisions on and registered antibiotic treatment, removal of pigs to sick pens and mortality. Pigs were weighed at weaning (N = 3139) and on day 33-35 post-weaning (N = 2898). Clinical examinations were carried out on day 4, 7 and 33-35 post-weaning. The effect of nursing strategy and weaning age on weight gain, clinical health and antibiotic treatments was analysed by mixed linear and logistic models. We found that pigs weaned at five weeks of age gained 103.6 g more daily compared to pigs weaned at four weeks during the 33-35 days post-weaning (<0.001). Weaning age affected diarrhoea prevalence, but the effect differed between herds. For pigs weaned at five weeks compared to four weeks of age, the odds for diarrhoea one week post-weaning was 0.7 times lower in one herd whereas the odds for diarrhoea were 2.0 and 1.4 times higher in the two other herds, respectively (P < 0.05). In all herds, we found fewer runted (OR=0.28, P < 0.001) and thin (OR=0.23, P < 0.001) pigs 33-35 days post-weaning in pigs weaned at five weeks of age compared to four weeks. Furthermore, in all herds, CF pigs were more likely to be removed to a sick pen or to die. In total, 5.9%, 13.6% and 64.9% of the studied weaned pigs were treated with antibiotics in the three herds, respectively. Treatment prevalence did not associate to weaning age or nursing strategy and did not in all cases appear to be linked with diarrhoea prevalence. The results indicate that a higher weaning age and less cross-fostering to some extend increase disease resilience post-weaning but herd specific factors interacted with the effects. The prevalence of pigs treated with antibiotics were herd dependent and may relate more to management decisions than to disease level.

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.

The Effect of Weaning and Slaughter Age on the Physicochemical and Sensory Characteristics of Arouquesa Beef-A PDO Portuguese Meat.

(1) Background: Autochthonous breeds meat is well accepted due to its sensory characteristics, perceived low environmental impact, and animal welfare. We aimed to evaluate the effect of weaning and slaughter age on the physicochemical and sensory characteristics of Arouquesa, a Portuguese Protected Designation of Origin (PDO) meat and to evaluate the psychological effect of knowing the weaning age on the consumer's hedonic evaluation. (2) Methods: Meat from 26 animals was assigned to 4 groups, with combinations of weaning (W) at 9 or 5 months and slaughter (S) at 9 or 12 months: W9-S9, W9-S12, W5-S9, and W5-S12. The meat was analysed for pH24h, colour (L*a*b*), cooking losses and shear force. A Check All that Apply test was made with 70 consumers; they were also asked to punctuate the hedonic appreciation of anonymous and weaning age-identified meat. (3) Results: W9-S9 were more tender, had lower shear force, and was juicier than W5-S9. When animals were slaughtered at 12 months, there were no differences in the physicochemical and sensory characteristics between the weaning ages. The effect of information about the weaning age influences the consumer's hedonic evaluation, as revealed by the comparison between the anonymous and identified samples. (4) Later weaning resulted in more tender meat when the slaughter was at 9 months and positively impacted consumer perception.

A field trial on the effect of cross-fostering on performance, clinical health and antibiotic usage during the suckling period of pigs.

Cross-fostering is a common nursing strategy in pig production, but there is sparse evidence on its effect on antibiotic usage and disease occurrence in piglets. The objective of this study was to compare the effect of two nursing strategies on antibiotic usage, disease occurrence, weight gain and mortality in piglets. A 2×2 randomized factorial experiment was conducted in three Danish commercial pig production herds. The factors were nursing strategy (cross-fostering allowed (CF) vs. cross-fostering not allowed after initial litter equalisation (non-CF)) and weaning age (four vs. five weeks). In CF litters, the herd's usual cross-fostering strategy was applied. Piglets were followed individually from birth until weaning. Data was collected on antibiotic usage, mortality, weight gain and clinical disease. Only individual antibiotic treatments were allowed. At litter level, the effect of nursing strategy (CF vs. non-CF) on average daily gain, mortality, antibiotic treatment, clinical disease, face wounds and carpal wounds was analysed. In total, 241 litters were used for the data analysis. Approximately 30% of the CF litters were cross-fostered (either given a nurse sow, mingled with non-siblings or both) during the nursing period. The odds for antibiotic treatment during the suckling period were 1.58 times higher for CF litters compared to non-CF litters (P < 0.001). Across experimental groups, 60.8% of antibiotic treatments were administered for leg diseases. In CF litters, 15.7-21.3% of the antibiotic treatments were directed against diarrhoea, whereas in non-CF litters this was the case for less than 1%. In CF litters, the odds for carpal wounds were 1.40 times higher than in non-CF litters (P = 0.005). There was a tendency towards a higher occurrence of face wounds (OR = 1.30, P = 0.095) and clinical disease (OR = 1.25, P = 0.059) at weaning in CF litters compared to non-CF litters. There was no difference in average daily gain and mortality from birth to weaning between CF and non-CF litters. The results show that cross-fostering increases antibiotic usage in piglets during the nursing period and tends to affect the clinical health at weaning negatively.

Effects of Fermented Feed on the Growth Performance, Intestinal Function, and Microbiota of Piglets Weaned at Different Age.

The beneficial function of fermented feed in livestock industry has been widely investigated. However, little is known about the effects of fermented feed on different weaned-day piglets. This study aimed to investigate the effects of fermented diet on the growth performance, intestinal function, and microbiota of piglets weaned at the age of 21 and 28 days. The results found that weaning on day 21 significantly increased (p < 0.05) average daily gain (ADG), and average daily feed intake (ADFI) (calculated based on wet weight and dry matter), while reduced (p < 0.05) feed to gain ratio (F:G), the activities of trypsin and lipase of jejunum and the villus height of ileum, compared with 28-days weaning. The protein levels of Occludin, Claudin-1, and ZO-1 of ileum in the groups weaning on day 21 were less (p < 0.05) than the groups weaning on day 28. Moreover, dietary supplementation with fermented diet upregulated (p < 0.05) the Occludin, Claudin-1, and ZO-1 proteins of ileum, compared with the groups treated with control diet both weaning on day 21 and 28. In addition, dietary supplementation with fermented diet decreased (p < 0.05) the relative abundance of Clostridia (class) and increased (p < 0.05) the Bacteroidia (class) level of cecal microbiota, compared with the groups treated with control diet both weaning on day 21 and 28. However, supplementation with fermented diet did not affect the concentrations of short-chain fatty acids in the cecum (p > 0.05). Therefore, our data suggest that the feed digestibility is improved in piglets weaned at 21 days, but intestinal barrier function is weaker than in piglets weaned at 28 days. However, compared with feeding control diet, supplementation with fermented diet both improved the feed conversion and intestinal barrier function of weaned piglets by modulating intestinal microbiota.

Weaning age influences indicators of rumen function and development in female Holstein calves.

BACKGROUND: Prenatal and postnatal conditions are crucial for the development of calves. Primiparous cows are still maturing during pregnancy, thus competing with the nutritional needs of their offspring. Therefore, mature cows might provide a superior intrauterine condition. Furthermore, weaning calves at an older age might affect them positively as well by reducing stress and offering time for various organs and their functions to develop. We aimed to evaluate effects of mothers' parity and calves' weaning age on gastrointestinal development and corresponding acid-base balance. Fifty-nine female German Holstein calves (about 8 days old) were investigated in a 2 × 2 factorial experiment with factors weaning age (7 vs. 17 weeks) and parity of mother (primiparous vs. multiparous). Calves were randomly assigned to one of these four groups. Animal behavior that was observed included resting, chewing and active behavior. RESULTS: Behavioral patterns were interactively affected by time and weaning age. Rumen sounds per 2 min increased in early-weaned calves during their weaning period. In late-weaned calves a consistently increase in rumen sounds was already recorded before their weaning period. Urinary N-containing compounds (creatinine, hippuric acid, uric acid, urea, allantoin) were interactively affected by time and weaning age. Concentrations of all measured compounds except urea increased during early weaning. All except hippuric acid concentration decreased in early-weaned calves after weaning. In late-weaned calves allantoin and uric acid increased before weaning and did not change during weaning. CONCLUSION: These results suggest that late-weaned calves developed adequate rumen functions and acid-base balance, whereas early-weaned calves might have suffered from ruminal acidosis and catabolism. Weaning calves at 7 weeks of age might be too early for an adequate rumen development.

Impacts of weaning age on dietary needs of whey permeate for pigs at 7 to 11 kg body weight.

BACKGROUND: Whey permeate is an effective lactose source for nursery pigs and the most benefits are obtained when pigs are at 7 to 11 kg BW. Altering weaning ages could cause different length of early-weaner phases until 7 kg BW and thus it would influence the dietary need of whey permeate during 7 to 11 kg BW of pigs. This study aimed to evaluate if weaning ages would affect the dietary needs of whey permeate for optimum growth performance of pigs at 7 to 11 kg BW. METHODS: A total of 1,632 pigs were weaned at d 21 (d 21.2 ± 1.3) or d 25 (d 24.6 ± 1.1) after birth. All pigs had a common early-weaner feeds until they reached 7 kg BW. When pigs reached 7 kg BW within a weaning age group, they were allotted in a randomized complete block design (2 × 4 factorial). Two factors were weaning age groups (21 and 25 d of age) and varying whey permeate levels (7.50%, 11.25%, 15.00%, and 18.75%). Data were analyzed using the GLM and NLIN procedures of SAS for slope-ratio and broken-line analyses to determine the growth response to whey permeate and optimal daily whey permeate intake for the growth of the pigs weaned at different ages. RESULTS: Pigs weaned at 21 d of age had a common diet for 11 d to reach 7 kg BW whereas pigs weaned at 25 d of age needed 2 d. The G:F of pigs weaned at 25 d of age responded to increased daily whey permeate intake greater (P < 0.05) than pigs weaned at 21 d of age. Breakpoints were obtained (P < 0.05) at 88 and 60 g/d daily whey permeate intake or 17.0% and 14.4% of whey permeate for G:F of pigs weaned at 21 and 25 d of age, respectively. CONCLUSION: Pigs weaned at an older age with a short early-weaner phase had a greater growth response to whey permeate intake compared with pigs weaned at a younger age with a long early-weaner phase. Altering weaning ages affected dietary needs of whey permeate for optimum growth performance of pigs from 7 to 11 kg BW.

Effects of Weaning Age at 21 and 28 Days on Growth Performance, Intestinal Morphology and Redox Status in Piglets.

The study objective was to assess effects of different weaning ages on growth performance, intestinal morphology and redox status in Duroc × Landrace × Large White piglets (n = 96) fed diets without antibiotic growth promoters. Piglets were selected from 24 litters based on similar body weight at 14 d of age. All piglets were allocated to two groups in a completely random design with six replicates and eight pigs per replicate (four barrows and four gilts), which were weaned at 21 (n = 48; BW = 6.87 ± 0.33 kg) and 28 (n = 48; BW = 8.49 ± 0.41 kg) days of age. After weaning, pigs were fed a corn-soybean meal-based diet. Average daily gain (ADG), average daily feed intake (ADFI), feed conversion (F:G), diarrhea incidence, gastrointestinal pH, intestinal morphology and redox status were determined. Pigs weaned at 28 d displayed increased ADG from d 8 to 14 (p < 0.01) compared with pigs weaned at 21 d. Pigs weaned at 28 d had a higher ADFI from d 0 to 7 (p < 0.01), d 8 to 14 (p < 0.01), d 15 to 28 (p < 0.05) and during the entire experimental period (p < 0.01) compared with pigs weaned at 21 d. Pigs weaned at 21 d had an improved F:G from d 15 to 28 (p < 0.05) compared with pigs weaned at 28 d. Pigs weaned at 28 d had decreased diarrhea incidence from d 8 to 14 (p < 0.01) and the entire experimental period (p < 0.01) compared with pigs weaned at 21 d. On d 28, the pH of the stomach contents in pigs weaned at 21 d was significantly higher compared with pigs weaned at 28 d (p < 0.01). On d 14, the morphology of the duodenum, jejunum and ileum in pigs weaned at 28 d was improved compared with pigs weaned at 21 d. During the experiment period, the antioxidant abilities of pigs weaned at 28 d of the heart, liver, kidney, intestinal and serum were better than pigs weaned at 21 d. In conclusion, intestinal morphology, pH of the stomach and antioxidant status of pigs weaned at 28 d were better than pigs weaned at 21 d. These factors supported better growth performance and decreased diarrhea incidence.

Weaning Age Affects the Development of the Ruminal Bacterial and Archaeal Community in Hu Lambs During Early Life.

Weaning plays an important role in many animal processes, including the development of the rumen microbiota in ruminants. Attaining a better understanding of the development of the rumen microbial community at different weaning stages can aid the identification of the optimal weaning age. We investigated the effects of weaning age on ruminal bacterial and archaeal communities in Hu lambs. Thirty male Hu lambs were randomly assigned to two weaning-age groups: a group weaned at 30 days of age (W30) and a group weaned at 45 days of age (W45), with each group having five replicate pens. On the weaning day (day 30 for W30 and day 45 for W45) and at 5 days postweaning [day 35 for W30 (PW30) and day 50 for W45 (PW45)], one lamb from each replicate was randomly selected and sacrificed. Rumen contents were collected to examine the ruminal microbiota. Compared to W30, PW30 had a decreased relative abundance of Bacteroidetes. At genus level, the extended milk replacer feeding (W45 vs. W30) increased the relative abundance of Ruminococcus while decreased that of Prevotella and Dialister. Compared to W30, PW30 exhibited decreased relative abundances of Prevotella, Dialister and Bacteroides but an increased unclassified Coriobacteriaceae. No significant difference was noted in the detected archaeal taxa among the animals. The function "biosynthesis of secondary metabolites" was less predominant in PW30 than in W30, whereas the opposite held true for "metabolism of cofactors and vitamins." Some bacterial genera were significantly correlated with rumen volatile fatty acid (VFA) concentration or other animal measures, including negative correlations between ruminal VFA concentration and unclassified Mogibacteriaceae and unclassified Veillonellaceae; positive correlations of ruminal papillae length with Fibrobacter and unclassified Lachnospiraceae, but negative correlations with Mitsuokella and Succiniclasticum; and negative correlations between plasma D-lactate concentration and Prevotella, unclassified Paraprevotellaceae, and Desulfovibrio. Our results revealed that the ruminal bacterial community underwent larger changes over time in lambs weaned at 30 days of age than in lambs weaned half a month later. Thus, extending milk replacer feeding to 45 days weaning was recommended from the perspective of the rumen microbial community in the Hu lamb industry.

Disentangling direct and indirect determinants of the duration of maternal care in brown bears: Environmental context matters.

The duration of maternal care, an important life-history trait affecting population dynamics, varies greatly within species. Yet, our understanding of its predictors is limited, mostly correlative and subject to misinterpretations, due to difficulties to disentangle the role of maternal- and offspring-related characteristics. We conducted path analysis on a dataset including 217 brown bear litters captured over a 29-year period in two populations in Sweden ('North' and 'South') facing contrasting environmental conditions to identify and quantify the causes of variation in the duration of maternal care (1.5 or 2.5 years). We showed that the causal determinants of the duration of maternal care were context-dependent. Contrary to their expected central role in the determination of the duration of maternal care, yearling mass and its direct determinants (i.e. litter size and maternal mass) were only important in the North population, where environmental conditions are harsher and the cost of extended maternal care presumably higher. In the South, the duration of maternal care was not caused by yearling mass nor any maternal or litter characteristics. Extension of maternal care may thus result from factors independent from maternal and offspring condition in the South, such as an artificial hunting-induced selection for longer maternal care through the legal protection of family groups. Our results provide an important contribution to our very limited knowledge of the direct and indirect determinants of the duration of maternal care and highlight the importance of accounting for the environmental context when assessing maternal reproductive tactics.

Relationship between weaning age and antibiotic usage on pig growth performance and mortality.

A total of 2,184 pigs (DNA 600 × PIC L42) were used to evaluate the effects of weaning age and antibiotic (AB) use on pig performance from weaning to marketing in a commercial production system. Experimental treatments were arranged in a 3 × 2 factorial with main effects of weaning age (18.5, 21.5, or 24.5 d of age) and with the use of ABs or an antibiotic-free (NAE) program. At birth, pigs were ear tagged, and the date of birth and sex recorded. Pigs were weaned from a 4,000-sow farm over four consecutive weeks. Four weaning batches (one per week) of 546 pigs were used. Each weaning batch had one-third of pigs of each weaning age. Pigs were placed in pens by weaning age and then randomly assigned to an AB or NAE program. There were 14 replicate pens per treatment and 26 pigs per pen (13 barrows and 13 gilts). Pigs allocated to the AB program were fed a diet containing 441 mg/kg chlortetracycline (CTC) from day 8 to 21 postweaning. They were also administered 22 mg/kg of body weight (BW) of CTC via drinking water for five consecutive days after a porcine respiratory and reproductive syndrome outbreak during week 7 after weaning. In the first 42 d postweaning, increasing weaning age improved (linear, P < 0.001) BW at day 42, average daily gain (ADG), and average daily feed intake (ADFI). From weaning to 197 d of age, increasing weaning age increased (linear, P < 0.001) ADG and ADFI. Pigs on the AB program had greater (P = 0.031) ADG and ADFI compared with NAE pigs. An interaction (linear, P = 0.005) was observed for feed efficiency (G:F). When ABs were provided, increasing weaning age did not result in any change in G:F; however, in the NAE program, increasing weaning age increased G:F. Pigs on the AB program had lower (P < 0.001) total losses (mortality and removals) than those on the NAE program. Increasing weaning age marginally (linear, P = 0.097) decreased total losses. Increasing weaning age decreased (quadratic, P < 0.001) the number of pigs treated with an injectable AB but the AB program did not (P = 0.238). The weight sold (at 197 d of age) per pig weaned was increased (linear, P = 0.050) by increasing weaning age and by using AB in feed and water (P = 0.019). In summary, increasing weaning age linearly improved most of the pig performance criteria and relatively the short-term use of ABs reduced mortality and removals with both factors contributing to increased weight sold per pig weaned.

Impact of increasing weaning age on pig performance and belly nosing prevalence in a commercial multisite production system.

The effects of increasing weaning age in a commercial production system on nursery and finishing performance were evaluated. A total of 1,176 pigs (PIC 337 × Camborough) were used in a 136-d growth trial with 14 and 10 replications/weaning age on the nursery and finishing phases, respectively. Treatments included weaning litters at 19, 22, 25, or 28 d of age. In the nursery, as weaning age increased, initial (5.04, 5.70, 6.52, and 7.26 kg) and final body weight (BW) (18.2, 19.8, 23.0, and 25.1 kg) increased (linear, P < 0.001). Increasing the weaning age reduced (linear, P < 0.001) the prevalence of pigs exhibiting belly nosing (27.6%, 15.0%, 6.5%, and 1.4%) during the first 3 wk. The percentage of pigs losing weight during the first week after weaning (35.1%, 28.7%, 12.4%, and 9.2%) decreased (linear, P < 0.001) as weaning age increased. Average daily gain (ADG; 295, 320, 374, 406 g/d) and average daily feed intake (493, 534, 619, 661 g/d) increased (linear, P < 0.001), while feed efficiency (G:F) (596, 599, 604, and 615) tended to increase (linear, P = 0.081) with weaning age. Removal rate (8.01%, 3.79%, 2.29%, and 1.65%) declined (linear, P = 0.001) as weaning age increased, while there was no evidence of difference (P = 0.463) in mortality rate (0.71%, 0.36%, 0.96%, 1.04%). In the finishing period, BW at 136 d post-weaning (114.9, 117.8, 124.7, and 126.5 kg) and ADG (1.02, 1.04, 1.08, and 1.07 kg/d) improved (linear, P < 0.001). There was no evidence of differences (P > 0.24) in removal (1.5%, 2.4%, 1.0%, and 0.0%) or mortality rates (0.9%, 1.0%, 1.0%, and 1.4%) with changes in weaning age. When performance was analyzed at a common day of life (164 d of age), no effects of weaning age (P > 0.25) were found for BW (125.2, 124.4, 128.0, and 126.5 kg) and lifetime ADG (growth rate from birth to market) (754, 751, 774, and 762 g/d). The BW sold per pig weaned increased (linear, P < 0.001) with weaning age. Even though the slope indicated a linear response, the magnitude of improvement was high until 25 d, before exhibiting diminishing returns from 25 to 28 d. Thus, the study suggests that increasing the weaning age can be an effective strategy to improve the overall performance in a commercial system. Although lifetime performance was not affected by the weaning age range studied, the consistent effect in the nursery and the increment in the number of pigs reaching the market facilitated by the improvement in the removal rate in the nursery phase imply that 25 d is the optimal weaning age.

Weaning Holstein Calves at 17 Weeks of Age Enables Smooth Transition from Liquid to Solid Feed.

Development of calves depends on prenatal and postnatal conditions. Primiparous cows were still maturing during pregnancy, which can lead to negative intrauterine conditions and affect the calf's metabolism. It is hypothesized that weaning calves at higher maturity has positive effects due to reduced metabolic stress. We aimed to evaluate effects of mothers' parity and calves' weaning age on growth performance and blood metabolites. Fifty-nine female Holstein calves (38.8 ± 5.3 kg birth weight, about 8 days old) were used in a 2 × 2 factorial experiment with factors weaning age (7 vs. 17 weeks) and parity of mother (primiparous vs. multiparous cows). Calves were randomly assigned one of these four groups. Live weight, live weight gain and morphometry increased over time and were greater in calves weaned later. Metabolic indicators except total protein were interactively affected by time and weaning age. Leptin remained low in early-weaned calves born to primiparous cows, while it increased in the other groups. The results suggest that weaning more mature calves has a positive effect on body growth, and calves born to primiparous cows particularly benefit from this weaning regimen. It also enables a smooth transition from liquid to solid feed, which might reduce the associated stress of weaning.

Weaning age and post-weaning nursery feeding regime are important in improving the performance of lightweight pigs.

The aim was to investigate the effect of weaning age, weaning weight, and nursery feeding regime on post-weaning performance. The focus was on pigs weaned light, as they may be better off when weaned at a later age and/or offered a specialist nursery feeding regime. Piglets (n = 1,448) from one farrowing batch of 110 sows that farrowed over 2 wk were individually weighed and their morphometric measurements were taken at birth. Pigs were weaned on the same day, but variation in birth date resulted in variable weaning ages (mean age day 34.1, SD = 2.5). The youngest 50% at weaning were classified Y and the oldest 50% as O; within an age class, the lightest 50% were classified L, the heaviest 50% as H, and housed accordingly. Pigs were individually weighed at weaning, 7 and 15 wk post-weaning. At weaning, Y were 6 d younger and 1.4 kg lighter than O pigs, whereas L were 3.2 kg lighter than H pigs. Pigs were randomly allocated to a 3-stage superior (SUP) or control (CON) nursery feeding regime, with SUP pigs having a 65% greater allowance (on a kg/pig basis) of the first and second stage feeds than the CON. Pigs weaned Y had a higher mortality rate from weaning to 7 wk post-weaning than pigs weaned O (9.14% vs. 4.98%; P = 0.046). As expected, age and weight significantly (P < 0.001) affected performance to both 7 and 15 wk post-weaning: at 15-wk pigs weaned Y were 5.5 kg lighter than pigs weaned O; pigs weaned L were 9.0 kg lighter than H pigs. It was estimated that pigs weaned YL needed ~4 d more (P = 0.018) to reach 60 kg BW than pigs weaned OL. Feed intake was not affected by feeding regime, age and weight, or their interactions. Performance was not affected by feeding regime (P > 0.05), but was affected by the weight × feeding regime interaction (P = 0.044) to 7 wk post-weaning: L pigs on SUP were 1.2 kg heavier than L pigs on the CON regime; this was not the case for the H pigs. Performance up to 7 wk post-weaning was positively associated with birth weight to cranial circumference ratio and weaning weight (P < 0.05) for both YL and OL pigs; for the latter, additional performance predictors were weaning age (P = 0.044) and feeding (P = 0.027). Improved growth for L pigs up to 7 wk post-weaning could be obtained by a greater allowance of the nursery diets. However, weaning at a later age benefitted the performance of L pigs to a common BW, suggesting that this might be a strategy with longer term benefits.

Weaning Ages Do Not Affect the Overall Growth or Carcass Traits of Hu Sheep.

This study aimed to determine effects of weaning ages on growth, rumen development, and carcass characteristics and meat quality of Hu lambs. Thirty male Hu lambs were randomly divided into two weaning age groups: Weaned at 30 (W30) or 45 (W45) d of age. Blood samples were collected on the day of weaning before lambs (n = 5) were slaughtered, and then rumen sample was collected immediately after they were slaughtered. The intake of all feeds increased with age (p < 0.05), but were not affected by weaning age (p > 0.05). Oxidative stress indicators and immune variables, the plasma biochemical parameters did not differ between the two different weaning ages (p > 0.05). The two weaning age groups also had similar (p > 0.05) concentration of ruminal total volatile fatty acid. The two weaning age groups did not differ in body weight, carcass characteristics, or meat quality (p > 0.05) at d 120. These results indicate that weaning half a month earlier than the typical weaning age does not significantly affect the growth, ruminal development, or carcass characteristics of Hu lambs, and they can be weaned at 30 d of age to improve production efficiency.

Understanding mammary activity in red-rumped agouti and implications for management and conservation of this Neotropical game species / Compreendendo a atividade mamária na cutia e as implicações para o manejo e a conservação desta espécie cinegética Neotropical

Abstract The red-rumped agouti (Dasyprocta leporina) produces precocial young and is the most hunted and farmed game species in several Neotropical countries. An understanding of the reproductive biology, including the relationship between litter size and teat functionality is crucial for conservation management of this animal. In precocial mammals, as the red-rumped agouti, maintaining maternal contact to learn foraging patterns may be more important than the energy demands and nutritional constraints during lactation and suckling may not play important roles when compared to altricial mammals. Therefore, in this study we evaluated the relationship between mammary functionality with litter size, litter birth weight, and parturition number in captive red-rumped agouti. Functionality was assessed by manual palpation of teats from un-sedated females (N=43). We compared the average birth weight of all newborns, male newborns and female newborns among agoutis with different litter sizes and different parturitions by one way ANOVA's, while Pearson's Chi-squared tests were used to detect relationships between teat functionality, litter size, and parturition number. Parturition number had no effect on the mean birth weight of all young (F0.822, P > 0.05), male young (F0.80, P > 0.05) or female young (F0.66, P > 0.05) in the litters. We found (i) no significant correlations (P > 0.05) between teat functionality and litter size and (ii) no significant correlations (P > 0.05) between teat functionality and parturition number. This suggests that whilst all teat pairs were functional, functionality was a poor indicator of litter size; suggesting that female agouti young may not have a high dependency on maternal nutrition; an possible evolutionary strategy resulting in large wild populations; hence its popularity as a game species.

Resumo A cutia (Dasyprocta leporina) produz filhotes precoces, e é a espécie cinegética mais caçada e criada em muitos países neotropicais. O entendimento da biologia reprodutiva, incluindo a relação entre o tamanho da ninhada e a funcionalidade das glândulas mamárias é crucial para o manejo conservacionista deste animal. Nos mamíferos precoces, como a cutia, manter o contato materno para a aprendizagem de padrões de forrageamento pode ser mais importante do que a demanda energética e de restrição nutricional durante a lactação, e a amamentação pode não desempenhar um papel importante quando comparado aos mamíferos altriciais. Portanto, neste estudo nós avaliamos a relação entre a funcionalidade mamária com o tamanho da ninhada, peso ao nascer da ninhada, e o número de partos em cutias cativas. A funcionalidade foi avaliada por meio de palpação manual das glândulas mamárias em fêmeas não sedadas (N=43). Nós comparamos a média do peso ao nascer de todos os recém-nascidos, macho e fêmeas recém-nascidos entre cutias com diferentes tamanhos de ninhadas e diferentes parturições, por meio da análise one-way ANOVA unifatorial; enquanto o teste do chi-quadrado de Pearson foi utilizado para detectar as relações entre a funcionalidade da glândula mamária, o tamanho da ninhada e o número de partos. O número de partos teve efeito na média de peso ao nascer dos filhotes (F0,822, P > 0,05), filhotes machos (F0,80, P > 0,05) ou filhotes fêmeas (F0,66, P > 0,05) nas ninhadas. A análise bivariada de Pearson (i) não mostrou correlação (P > 0,05) entre a funcionalidade da glândula mamária e o tamanho da ninhada e (ii) nenhuma correlação significativa (P > 0,05) entre a funcionalidade da glândula mamária e o número de parições. Os resultados sugerem que, embora todos os pares de tetas fossem funcionais, as cutias recém-nascidas podem não depender da nutrição materna para sobreviver; .embora todos os pares de tetas sejam funcionais, as cutias recém nascidas aparentemente não dependem da nutrição materna para sua sobrevivência; esta é, provavelmente, uma estratégia evolutiva que resulta em grandes populações da cutia em vida livre; e que pode explicar sua popularidade como espécie cinegética

Core gut microbiota in Jinhua pigs and its correlation with strain, farm and weaning age.

Gut microbial diversity and the core microbiota of the Jinhua pig, which is a traditional, slow-growing Chinese breed with a high body-fat content, were examined from a total of 105 fecal samples collected from 6 groups of pigs at 3 weaning ages that originated from 2 strains and were raised on 3 different pig farms. The bacterial community was analyzed following high-throughput pyrosequencing of 16S rRNA genes, and the fecal concentrations of short-chain fatty acids (SCFAs) were measured by gas chromatograph. Our results showed that Firmicutes and Bacteroidetes were the dominant phyla, and Lactobacillus, Streptococcus, Clostridium, SMB53, and Bifidobacterium were the most abundant genera. Fifteen predominant genera present in every Jinhua pig sample constituted a phylogenetic core microbiota and included the probiotics Lactobacillus and Bifidobacterium, and the SCFA-producing bacteria Clostridium, Prevotella, Bacteroides, Coprococcus, Roseburia, Ruminococcus, Blautia, and Butyricicoccus. Comparisons of the microbiota compositions and SCFA concentrations across the 6 groups of pigs demonstrated that genetic background and weaning age affected the structure of the gut microbiota more significantly than the farm. The relative abundance of the core genera in the pigs, including Lactobacillus, Clostridium, Prevotella, Bacteroides, Roseburia, Ruminococcus, Blautia, and Butyricicoccus varied dramatically in pigs among the 2 origins and 3 weaning ages, while Oscillospira, Megasphaera, Parabacteroides, and Corynebacterium differed among pigs from different farms. Interestingly, there was a more significant influence of strain and weaning age than of rearing farm on the SCFA concentrations. Therefore, strain and weaning age appear to be the more important factors shaping the intestinal microbiome of pigs.