Fence-line Contact Research Articles

Can a gradual weaning and separation process reduce weaning distress in dam-reared dairy calves? A comparison with the 2-step method

The weaning and separation phase remains one of the biggest challenges for cow-calf-contact systems, but a gradual process that better mimics the naturally occurring reduction in milk intake has not yet been scientifically investigated. Therefore, the aim of our study was to compare behavioral and physiological indicators of distress in 3 mo-old dam-reared dairy calves (with previous full-time cow-calf contact) weaned and separated either via gradual reduction of contact time with the dam (GR, 1 week half day contact, 1 week morning contact, 1 week fence-line contact before complete separation, n = 18) or via 2-step weaning using a nose flap (NF, 2 weeks access to dam with a nose flap, 1 week fence-line contact before complete separation, n = 18). Behavior was recorded 1 week before (or for lying 3 weeks before) weaning start and during the 3 week weaning and separation period with direct observations on 4 d per week or via accelerometers (locomotor play, lying behavior). Blood and fecal samples were taken twice per week from weaning start until 3 weeks after weaning start. Calves were weighed weekly. Statistical analysis was conducted using (generalized) linear mixed models. Over the whole weaning and separation phase, NF calves showed a stronger decrease in the number of lying bouts, amount of locomotor play and average daily weight gains, as well as a higher increase in total mixed ration feeding time compared with GR calves, whereas GR calves vocalized more often and showed more searching behavior than NF calves. Also, the neutrophil:lymphocyte ratio of NF calves was elevated on d 3 after insertion of the nose flaps compared with baseline, but showed no change for GR calves on any sampling day. Overall, results point toward a favorable effect of a gradual weaning strategy on reduction of weaning and separation distress in dam-reared dairy calves, but the method requires further improvement from the protocol used in our study.

44 Identification of Vaginal Gene Expression Differences in Gilts Achieving Early or Late Puberty

Abstract A known predictor of reproductive success in swine breeding herds is age at puberty. Early puberty is associated with improved long-term reproductive performance. Additionally, it has been established that vaginal gene expression in gilts changes throughout reproductive development. The hypothesis was that vaginal gene expression was correlated with estrus expression and therefore likelihood of reproductive success. Pre-pubertal gilts (n = 29) were followed from 70 d of age until first estrus or 215 d of age. Vaginal epithelia were collected using a swabbing technique at five key timepoints during reproductive development [70 (on farm arrival), 100 (mid-folliculogenesis), 130, 160 d of age, and first estrus or end of trial]. Boar exposure began on 160 d of age with 15 minutes of fenceline contact at 0700 h daily with trained technicians observing for signs of standing estrus (i.e., erect ears, swollen, pink vulva, allowing back pressure). By 215 d of age, 19 females were classified as expressing estrus early (160 to 181 d), 4 were average (181 to 202), and 6 were late or as anestrus (202 to 215 d). A subset of 5 gilts that expressed estrus early and 5 gilts that expressed estrus late or as anestrus were used for further investigation of vaginal gene expression. Total RNA was isolated from vaginal samples at 3 timepoints (100, 130, and 160 d of age). Samples were sent to a commercial genomic sequencing laboratory for RNA sequencing. Each gene was scaled individually so that all genes were on the same scale for comparison, and the Welch two sample t-test was applied to determine statistical differences. A total of 53 genes were differentially expressed between the early estrus and late estrus or anestrus groups. Data were further screened to identify genes that were expressed in at least 3 gilts in either the early estrus or late estrus group at a given time point; this subset of 26 genes were selected for direct comparison at each time point. At 100 d of age, late estrus gilts had increased expression (P = 0.05) of a gene commonly found in females with polycystic ovary syndrome. At 130 d of age, genes associated with the innate immune response had greater relative expression (P < 0.05) in gilts expressing early estrus. At 160 d of age, genes associated with fat cell deposition had greater relative expression (P < 0.05) in the early estrus expression gilts. Distinct differences in transcripts during reproductive development may be putative biomarkers for detection of early estrus in pre-pubertal females.

A Pilot Study on the Feasibility of an Extended Suckling System for Pasture-Based Dairies.

This study investigated cow-calf productivity in a 10-week, pasture-based, extended suckling system featuring part-time cow-calf contact and once-a-day milking. A total of 30 dairy cows and their calves were assigned to two treatments: (1) cow and calf managed in an extended suckling system; or (2) cow and calf separated at birth and managed as usual. Cow-calf pairs grazed together during the day and spent the night separated by fence-line contact. The dams were reunited with the calves after once-a-day milking every morning. The commercial treatment pairs were separated after birth, and cows were milked twice a day and managed within the farm herd. Commercial calves were reared and managed as per commercial Australian practices. Cow-calf dams yielded 9 L/cow/day less saleable milk (p < 0.001), and their milk had lower fat (p = 0.04) but a higher protein percentage (p < 0.001) than commercial cows during pre-weaning. However, milk yield and composition were comparable post-weaning. Dam-suckled calves gained weight faster and were therefore weaned 2 weeks earlier than commercial calves, which were offered 8 L/day milk. This study has demonstrated a novel system of extended cow-calf suckling that could be practical to implement in pasture-based dairies. The long-term effects and scalability of the extended suckling system described here require further validation.

Effect of mother contact and voluntary colostrum suckling on growth, health and stress of neonatal buffalo calves

The aim of present study was to investigate the effect of full mother contact and voluntary colostrum suckling on the health, stress and growth performance of neonatal Murrah buffalo calves. For this, two experiments (exp.) were conducted involving exp.1, 24 mother-calf pairs were divided into three equal groups (eight pairs/each group). In no mother contact (NC) group, weaning was allowed immediately after birth. In restricted mother contact (RC) group, restricted contact was allowed twice daily. In fence-line mother contact (FC) group, calves were in full-time mother contact from birth to day (d) 5 and allowed voluntary colostrum suckling and thereafter fence-line contact. In exp.2, another 24 mother-calf pairs were selected and divided into two groups (12 pairs in each group), with the same conditions as the RC and FC groups in exp.1. Average daily gain, total protein and total Ig concentrations differed between different groups in both experiments. Cortisol levels were lower in FC followed by RC and lowest in NC calves, and similar results were observed in exp.2. It was concluded that the provision of full mother contact along with free choice colostrum suckling from birth to 5 days followed by fenceline mother contact and twice daily suckling at milking time abated the separation and weaning stress and remarkably improved the growth, immune status and health of Murrah buffalo calves as compared to the calves which were allowed only limited contact twice daily or the calves which were weaned at birth.

Effect of proximity to females on integument damage caused by self-enurination in male goats

In male goats, self-enurination (SE) is the downward turning of the head and shoulders while urinating onto the face and front legs. Although it provides important chemical cues to females, other males, and even self, it is a costly behavior that can create a range of problems including erythema, irritation, hair loss, and compromised skin. It was hypothesized that the extent of integument damage from SE on bucks' faces and front legs would be increased by housing bucks near females. Four bucks were housed with fence-line contact to females (“Near” bucks), and four bucks were housed without fence-line contact to females (“Far” bucks). Each buck was photographed every other week over an 18-wk period during the breeding season. During each imaging session, seven different photographic views were captured, and burn areas were quantified for each buck. Overall, more Near bucks had urine burn than Far bucks, and Near bucks developed urine burn earlier in the breeding season than did Far bucks. Housing bucks close to females increases the extent of integument damage from SE. These findings may help goat breeders develop management practices to improve animal well-being by minimizing urine burn injury to bucks.

Effect of Biostimulation on Some Behavioral Aspects and Energy Balance of Sahiwal Cows during Peri-estrual Period

Background: Energy is the major nutrient needed for dairy cattle and its insufficient intake has a detrimental effect on their reproductive activity. Methods: The aim of this study was to investigate the effect of biostimulation on behaviour and energy balance of Sahiwal cows during peri-estrus through 2 types of bull contact. For this, 24 postpartum cows were divided into 3 similar groups (T0, T1 and T2) of 8 cows each. In T0, cows were not exposed to bull; in T1 the cows were exposed to bull through a fence-line contact and in T2, the cows were in direct bull contact for 12 hours daily. Result: In first post-partum estrus, the feeding time was non-significant among 3 groups but in second estrus, mean time spent on feeding was significantly (p less than 0.05) lower in T0 than T1 and T2 groups. The mean rumination time on d-0 of first estrus was significantly (p less than 0.01) lower in T1 and T2 cows as compared to T0 cows. Mean rumination time on d-0 in second estrus was significantly (p less than 0.05) lower in T1 and T2 than in T0. Mean resting times in first estrus in T1 and T2 were significantly lower (p less than 0.05) than in T0. Mean resting time in d-0 of second estrus was significantly (p less than 0.05) lower in T1 and T2 than the T0. There was no significant difference in the mean dry matter intake and levels of BHBA and NEFA among 3 groups of cows. It was concluded that biostimulation of Sahiwal cows through direct or fence-line bull contact during peri-estrus period highly reduced their feeding, rumination and resting times without affecting their energy balance as compared to non-bull exposed cows.

102 Impact of weaning strategy on beef cow-calf behavior and activity

Abstract The objective of this study was to investigate the impact of three weaning strategies on cow and calf behavior and activity. Research has shown that weaning imposes stress on both the cow and the calf that can alter behavior, activity, and growth performance. Angus-based cow-calf pairs (n = 147) were randomly assigned to one of three treatment groups, abrupt weaning on d0 (Abrupt, n=50), fence-line contact for 7 days and then relocation of the cow on d7 (Fence, n=50), and late weaning by abrupt separation on d84 (Late, n = 47). Both cow and calf behaviors were observed over 7d prior to weaning and 7d post weaning activity for each treatment group. A single observer recorded activity and vocalizations for each animal twice in morning and evening on observation days. Calf activity was also continuously measured using accelerometers secured to collars worn by five calves per treatment group. Observation and activity data were analyzed using PROC MIXED of SAS. Significance was determined at P &amp;lt; 0.05 and a tendency at 0.05&amp;lt; P ≤0.10. The average activity units per day (AU/d) prior to weaning were similar among treatment groups. On d1 of weaning, Fence calves, who still had a visual contact with their dam, tended to have greater AU/d (P = 0.09) than the Abrupt calves and maintained a higher level of activity through d14 (P &amp;lt; 0.001). Late calves tended to have greater AU/d (P = 0.10) than Abrupt or Fence on d0-1 after their weaning. No difference in vocalizations (P = 0.41) by calves 7d post weaning were observed (1% Abrupt, 0% Fence, and 4% Late). More cows on Fence paced (1%) than Abrupt (0%) or Late (0%) (P &amp;lt; 0.05) in the 7d of fenceline contact. Late cows (2%) vocalized more than Abrupt (1%) or Fence (0%) when their calves were still with them (P &amp;lt; 0.05), but not after (P &amp;gt; 0.05) when no vocalizations were recorded. These results differ from the previous year study; therefore, further investigation of the impact of weaning strategy on cow-calf behavior and activity is warranted.

103 Impact of weaning strategy on beef cow-calf behavior and activity

Abstract The objective of this study was to investigate the impact of three weaning strategies on cow and calf behavior and activity. Research has shown that weaning imposes stress on both the cow and the calf that can alter behavior, activity, and growth performance. Angus-based cow-calf pairs (n = 147) were randomly assigned to one of three treatment groups, abrupt weaning on d0 (Abrupt, n = 50), fence-line contact for 7 days and then relocation of the cow on d7 (Fence, n = 50), and late weaning by abrupt separation on d84 (Late, n = 47). Both cow and calf behaviors were observed over 7d prior to weaning and 7d post weaning activity for each treatment group. A single observer recorded activity and vocalizations for each animal twice in morning and evening on observation days. Calf activity was also continuously measured using accelerometers secured to collars worn by five calves per treatment group. Observation and activity data were analyzed using PROC MIXED of SAS. Significance was determined at P &amp;lt; 0.05 and a tendency at 0.05&amp;lt; P ≤ 0.10. The average activity units per day (AU/d) prior to weaning were similar among treatment groups. On d1 of weaning, Fence calves, who still had a visual contact with their dam, tended to have greater AU/d (P = 0.09) than the Abrupt calves and maintained a higher level of activity through d14 (P &amp;lt; 0.001). Late calves tended to have greater AU/d (P = 0.10) than Abrupt or Fence on d0-1 after their weaning. No difference in vocalizations (P = 0.41) by calves 7d post weaning were observed (1% Abrupt, 0% Fence, and 4% Late). More cows on Fence paced (1%) than Abrupt (0%) or Late (0%) (P &amp;lt; 0.05) in the 7d of fenceline contact. Late cows (2%) vocalized more than Abrupt (1%) or Fence (0%) when their calves were still with them (P &amp;lt; 0.05), but not after (P &amp;gt;0.05) when no vocalizations were recorded. These results differ from the previous year study; therefore, further investigation of the impact of weaning strategy on cow-calf behavior and activity is warranted.

101 Impact of weaning strategy on beef cow and calf weight and body condition

Abstract Weaning is one of the largest stressors in an animal’s life and can have long term impacts on the animal. The objective of this study was to investigate the effect of weaning strategy on the weight and body condition of beef cattle. A total of 249 Angus-based pairs at two locations were assigned to one of three treatments: abrupt removal of the calf on d0 (Abrupt, n = 84), fenceline contact for 7 days followed by complete separation on d7 (Fence, n = 85), or late weaning d84 (Late, n = 80). Weaned calves were supplemented 0.23 kg/hd/d of grain as fed while Late were not supplemented. Weights were obtained on d0, 7, 14, 28, 56, 84, 91, and 112. Body condition scores were recorded monthly. Data were analyzed using PROC MIXED of SAS and weights were analyzed with repeated measures. Significance was determined at P &amp;lt; 0.05. During the initial week post-abrupt weaning, Abrupt calves lost weight, Fence maintained weight, and Late calves gained weight (-0.4, 0, and 0.7 kg/d, respectively; P &amp;lt; 0.05). Over the complete weaning period (d0 to 112), Abrupt and Late weaned differed (P &amp;lt; 0.05) in their gains, while Fence was not different (P &amp;gt;0.05) than either treatment (0.58, 0.64, and 0.62 kg/d, respectively). Cow overall ADG was not affected by weaning treatment (1.2, 0.8, and 0.5 kg/d, respectively; P &amp;gt; 0.05). From d28 to 84, lactating Late cows gained less weight than Abrupt and Fence (0.3, 0.8, 0.8 kg/d, respectively; P &amp;lt; 0.0001). This contributed to a -0.1 BCS decrease at d112 for Late compared to a 0.3 and 0.2 BCS gain for Abrupt and Fence, respectively (P &amp;lt; 0.0001). Cows weaning calves after 10 mo of lactation were lighter than cows weaned after 7 mo; however calves remaining with their dam maintained growth rates similar to grain supplemented weaned calves on pasture. While treatments influenced cow measures, all remained within normal values, therefore late weaning may be an option for producers to sell heavier calves without grain supplementation if marketing older calves.

100 Impact of weaning strategy on beef cow and calf weight and body condition

Abstract Weaning is one of the largest stressors in an animal’s life and can have long term impacts on the animal. The objective of this study was to investigate the effect of weaning strategy on the weight and body condition of beef cattle. A total of 249 Angus-based pairs at two locations were assigned to one of three treatments: abrupt removal of the calf on d0 (Abrupt, n = 84), fenceline contact for 7 days followed by complete separation on d7 (Fence, n = 85), or late weaning d84 (Late, n = 80). Weaned calves were supplemented 0.23 kg/hd/d of grain as fed while Late were not supplemented. Weights were obtained on d0, 7, 14, 28, 56, 84, 91, and 112. Body condition scores were recorded monthly. Data were analyzed using PROC MIXED of SAS and weights were analyzed with repeated measures. Significance was determined at P &amp;lt; 0.05. During the initial week post-abrupt weaning, Abrupt calves lost weight, Fence maintained weight, and Late calves gained weight (-0.4, 0, and 0.7 kg/d, respectively; P &amp;lt; 0.05). Over the complete weaning period (d0 to 112), Abrupt and Late weaned differed (P &amp;lt; 0.05) in their gains, while Fence was not different (P &amp;gt; 0.05) than either treatment (0.58, 0.64, and 0.62 kg/d, respectively). Cow overall ADG was not affected by weaning treatment (1.2, 0.8, and 0.5 kg/d, respectively; P &amp;gt;0.05). From d28 to 84, lactating Late cows gained less weight than Abrupt and Fence (0.3, 0.8, 0.8 kg/d, respectively; P &amp;lt; 0.0001). This contributed to a -0.1 BCS decrease at d112 for Late compared to a 0.3 and 0.2 BCS gain for Abrupt and Fence, respectively (P &amp;lt; 0.0001). Cows weaning calves after 10 mo of lactation were lighter than cows weaned after 7 mo; however, calves remaining with their dam maintained growth rates similar to grain supplemented weaned calves on pasture. While treatments influenced cow measures, all remained within normal values, therefore late weaning may be an option for producers to sell heavier calves without grain supplementation if marketing older calves.

Serum Anti-Mullerian Hormone and Estradiol Concentrations in Gilts and Their Age at Puberty.

Simple SummaryIt has been documented in several species that blood levels of the hormone, anti-Mullerian hormone (AMH), are an indirect measure of the number of ovarian follicles and that the number of ovarian follicles may be an indication of potential female fertility. In the present study, we determined AMH levels at various ages in immature female pigs and related these to potential measures of future fertility including age at puberty and numbers of ovarian follicles at puberty, and the gilt response to ovarian stimulation after puberty. Our results support the suggestion that blood levels of AMH are reflective of future fertility in gilts.For experiment one, blood samples were obtained from 200 gilts at 90, 120, 150, 180, and 200 days of age. Serum samples from the 30 youngest (166.1 ± 0.7 days) and 30 oldest (198.8 ± 0.6 days) gilts exhibiting estrus by 200 days, and a further 18 gilts that remained anestrus at 200 days, were assayed for serum concentrations of anti-Mullerian hormone (AMH) and estradiol (E2). Gilts younger at puberty had higher (p < 0.05) AMH levels than those older at puberty, and both groups had higher AMH levels than anestrus gilts (p < 0.05). Regardless of age, serum E2 was higher (p < 0.05) in gilts that achieved puberty than in gilts remaining anestrus. At spontaneous pubertal estrus detection, there was no effect of pubertal age on the number of preovulatory ovarian follicles. For experiment two, 152 prepubertal gilts received an intramuscular (IM) injection of 400 IU eCG plus 200 IU hCG and then received fence-line boar contact to detect estrus onset. Serum AMH concentrations were higher (p < 0.05) in the first 25 gilts to exhibit puberty than the last 28 gilts, with the first gilts also having more preovulatory follicles (p < 0.0001). Taken together, these data support an association between serum AMH concentrations and degree of physiological maturity and ovarian follicular development in gilts.

Influence of bull biostimulation on age at puberty and reproductive performance of Sahiwal heifers

Present study was undertaken to compare the effect of biostimulation by exposing the heifers to fenceline bull contact and fenceline + direct contact on age at puberty and reproductive performance of Sahiwal heifers. Pre-pubertal heifers (24) were allotted to 3 groups (8 animals each), i.e. non-bull exposed (NBE), fenceline bull exposed (FBE) and FBE + direct bull exposed (DBE) on the basis of age and body weight. In NBE group, heifers were not exposed to bull; in FBE group, heifers were exposed to the bull through a fenceline contact (24 h) and in FBE+DBE group, heifers were housed in a fenceline contact (24 h) with bull along with direct contact for 6 h through another bull in the heifer shed. Heifers were considered to have attained puberty if progesterone concentration was &gt;1 ng/ml. The mean age and body weight at puberty in FBE (19.33±0.36 months and 226.20±6.35 kg) and FBE+DBE (19.11±0.58 months and 224.19±4.54 kg) heifers were almost similar but significantly lower than NBE heifers (24.13±0.16 months and 262.50±8.50 kg). The average age at first service and first calving was similar in FBE (20.41±0.45 and 30.20±0.73 months) and FBE+DBE (20.78±0.36 and 29.90±0.44 months) heifers but significantly lower than NBE heifers (25.15±0.14 and 34.29±0.53 months). We conclude that biostimulation of heifers by fenceline contact with the bull is as effective as FBE + 6 h of daily direct bull contact in hastening the age at puberty and improving reproductive performance.

157 Impact of weaning strategy on heifer performance and reproductive development

Abstract Weaning is recognized as one of the most stressful times of a beef calf’s post-natal life. The objective of this study was to determine if weaning strategy impacts heifer development and reproduction. At 7 months of age, 96 predominantly Angus heifers at 2 locations were assigned to 1 of 3 weaning treatments: abrupt relocation of the calf on d0 (Abrupt, n = 32), fenceline contact starting on d0 prior to relocation of the calf on d7 (Fence, n = 33), and abrupt relocation of the calf on d84 (Late, n = 31). Calf weights, hip heights, and body condition scores (BCS) were collected to evaluate post-weaning performance. Reproductive tract scores (RTS; 0–5 scale, 5=most mature) were assigned every 54 days from d56 to d218. Heifers were synchronized using a 7-day CO-Synch + CIDR® protocol and artificially inseminated (AI) on d246. Data were analyzed using PROC MIXED of SAS with repeated measures. Statistical significance was determined at P ≤ 0.05. Late heifers were heavier at d28 and d56 than Abrupt and Fence (P &amp;lt; 0.05), but BW was similar across treatments starting at d84. Average daily gain (ADG) was greater for Late than Abrupt (0.39 and -0.03 kg/day respectively; P &amp;lt; 0.01) and tended to be greater than Fence (0.16 kg/day; P = 0.07) to d28; however, Late had lower ADG than Abrupt and Fence from d28-84 (0.66, 0.83, and 0.81 kg/day respectively; P &amp;lt; 0.05). No treatment differences were observed in BCS or hip height. Late tended to have greater RTS than Abrupt and Fence (2.54, 2.20, and 2.16 respectively; P ≤ 0.10) on d56, but there was no difference on or after d164. Fence tended to have greater AI conception rates than Abrupt and Late (66%, 44%, and 42% respectively; P ≤ 0.08). This data indicates there were initial performance differences based on weaning strategy, but this had minimal impact on heifer development.

Effect of bull biostimulation on the oestrous behaviour of pubertal Sahiwal (Bos indicus) heifers

The study was conducted to determine effects of biostimulation of Sahiwal heifers through fenceline bull contact and fenceline combined with direct bull contact on oestrous behaviour when there was ovulation occurring in the absence of behavioural oestrus (“silent oestrus - SE) and overt behavioural oestrus (OBE). Prepubertal Sahiwal heifers were allotted to three treatments (T0, T1, T2, n = 8 heifers/treatment). In the T0 group, there was no bull exposure; in T1, exposure to a bull through fenceline contact for 24 h and in T2, exposure to a bull as in T1 along with direct bull contact with another bull for a 6 -h period daily. The oestrous behaviours were recorded on day (d) −3, −2 and −1 (prior to oestrus), d 0 (day of oestrus) and d +3, +2 and +1 (post-estrus). With both SE and OBE, the mean frequency of sniffing, micturition, chin resting and standing to be mounted differed (P < 0.05) from d −2 to d +1 among treatment groups. The mean times devoted to eating, ruminating and lying during SE and OBE were less (P < 0.05) on d-1 and d 0 in heifers of all three groups than the respective values on reference days in both T1 and T2 groups. Biostimulation of Sahiwal heifers with bull exposure, therefore, resulted in greater expression of oestrous behaviour than in non-exposed heifers during the periods around when there was SE and OBE.

180 Impact of weaning strategy on calf performance, behavior, and activity

Abstract Weaning is known to be the most stressful time in a beef calf’s post-natal life. Weaning stress may have long-term impacts on cattle performance. This study was conducted to determine differences in calf stress under three weaning strategies. Two hundred twenty-nine Angus or Angus-Simmental cross pairs at two locations were assigned to one of three weaning treatments: abrupt removal of the calf on d 0 (Abrupt, n = 77), fenceline contact for 7 d prior to removal of the calf on d 7 (Fence, n = 79), and abrupt removal of the calf on d 84 (Late, n = 73). Behavioral observations were conducted pre- and post-weaning, and total activity was measured prior to and after weaning using accelerometers placed on collars on five calves per treatment. Calf weights, hip heights, and body condition scores (BCS) were collected to evaluate calf performance post-weaning. Data were analyzed using PROC MIXED of SAS. Statistical significance was determined at P &lt; 0.05 and a tendency at 0.05 0.10) by timing or strategy of weaning. Total activity was greater (P &lt; 0.05) in Abrupt than Fence on d 1 and d 2 post-wean (Abrupt 26772 and 22346 and Fence 22235 and 16691 relative activity units/hour, respectively). Calf activity was elevated (P &lt; 0.05) on day of weaning until d 2 post-wean then returned to pre-wean level by d 3 for all treatments. Short-term differences in calf performance warrant further exploration of the possible long-term effects on heifer development and steer feedlot performance.

57 Impact of weaning strategy on beef cow performance

Abstract It has been shown that physiologic stress in beef cattle can impact animal performance. Weaning stress is recognized as a major stress in a calf’s life. However, less is known of its impacts on the dam or developing fetus, as the dam is at the end of the second trimester at weaning. Therefore, the objective was to investigate the impact of weaning stress on cow performance. A total of 240 cows from two locations were assigned to one of three weaning strategies: abrupt removal of the calf on d 0 (n = 80), d 7 cow-calf fenceline contact (n = 81), and late weaning on d 84 (n = 79). Cows averaged 16 and 24 weeks of gestation on d 0 and d 84 respectively. Weights and BCS were obtained monthly. Behavioral observations occurred over the week before and after weaning for each weaning period. Five late-wean cows per location were milked on d 14 and d 70 to estimate milk yield throughout the late wean period. Data were analyzed using the MIXED procedure of SAS with BW and BCS utilizing repeated measures. Means are declared different at P ≤ 0.05. The ADG over the course of the study was lower (P &lt; 0.05) for the late weaned cows compared to the abrupt weaned cows. This was also reflected by change in body condition where late weaned cows dropped from a 5.7 to a 4.9 (P &lt; 0.05) over the 105 d. Milk production in late weaned cows decreased over time (6.0 and 4.4 kg/d for d 14 and 70, respectively; P = 0.05). Energy expenditure for lactation may have contributed to the drop in BCS of the late weaned compared with the non-lactating cows and could compromise third trimester growth of calf in utero. The results of this study warrant further exploration of the effect of weaning stress on dams and their developing fetuses.

11 Impact of weaning strategy on calf performance, behavior, and activity

Abstract Weaning is known to be the most stressful time in a beef calf’s post-natal life. Weaning stress may have long-term impacts on cattle performance. This study was conducted to determine differences in calf stress under three weaning strategies. Two hundred twenty-nine Angus or Angus-Simmental cross pairs at two locations were assigned to one of three weaning treatments: abrupt removal of the calf on d 0 (Abrupt, n = 77), fenceline contact for 7 d prior to removal of the calf on d 7 (Fence, n = 79), and abrupt removal of the calf on d 84 (Late, n = 73). Behavioral observations were conducted pre- and post-weaning and total activity was measured prior to and after weaning using accelerometers placed on collars on five calves per treatment. Calf weights, hip heights, and body condition scores (BCS) were collected to evaluate calf performance post-weaning. Data were analyzed using PROC MIXED of SAS. Statistical significance was determined at P &lt; 0.05 and a tendency at 0.05&lt;p&lt;0.10. Skeletal growth via hip height was not affected by weaning treatment. During the first 28 d after initial weaning, the Abrupt calves lost while the Late weaned calves gained weight (-0.09 and 0.49 kg/d, respectively; P &lt; 0.05). Fence were intermediate weight and tended to be different from both treatments (0.02 kg/d; P = 0.09). Overall ADG was not affected (P &gt; 0.10) by timing or strategy of weaning. Total activity was greater (P &lt; 0.05) in Abrupt than Fence on d 1 and d 2 post-wean (Abrupt 26772 and 22346 and Fence 22235 and 16691 relative activity units/hour, respectively). Calf activity was elevated (P &lt; 0.05) on day of weaning until d 2 post-wean then returned to pre-wean level by d 3 for all treatments. Short-term differences in calf performance warrant further exploration of the possible long-term effects on heifer development and steer feedlot performance.

48 Impact of weaning strategy on beef cow performance

Abstract It has been shown that physiologic stress in beef cattle can impact animal performance. Weaning stress is recognized as a major stress in a calf’s life. However, less is known of its impacts on the dam or developing fetus, as the dam is at the end of the second trimester at weaning. Therefore, the objective was to investigate the impact of weaning stress on cow performance. A total of 240 cows from two locations were assigned to one of three weaning strategies: abrupt removal of the calf on d 0 (n = 80), d 7 cow-calf fenceline contact (n = 81), and late weaning on d 84 (n = 79). Cows averaged 16 and 24 weeks of gestation on d 0 and d 84 respectively. Weights and BCS were obtained monthly. Behavioral observations occurred over the week before and after weaning for each weaning period. Five late-wean cows per location were milked on d 14 and d 70 to estimate milk yield throughout the late wean period. Data were analyzed using the MIXED procedure of SAS with BW and BCS utilizing repeated measures. Means are declared different at P ≤ 0.05. The ADG over the course of the study was lower (P &lt; 0.05) for the late weaned cows compared to the abrupt weaned cows. This was also reflected by change in body condition where late weaned cows dropped from a 5.7 to a 4.9 (P &lt; 0.05) over the 105 d. Milk production in late weaned cows decreased over time (6.0 and 4.4 kg/d for d 14 and 70, respectively; P = 0.05). Energy expenditure for lactation may have contributed to the drop in BCS of the late weaned compared with the non-lactating cows and could compromise third trimester growth of calf in utero. The results of this study warrant further exploration of the effect of weaning stress on dams and their developing fetuses.

Influence of bull exposure on the behavioural intensity of estrus in Sahiwal heifers (Bos Indicus)

Present study was conducted to study the influence of presence of bull on the behavioural signs of estrus expressed by Sahiwal heifers. For this experiment, a total of 24 Sahiwal heifers were allotted to 3 groups (T0, T1 and T2) of 8 animals each, based on the age and body weight. In T0, the heifers were isolated from the bull; in T1 group, the heifers were in contact with the bull through a fenceline exposure and in T2 group, the heifers were exposed through a fenceline contact (24 hours) with bull along with direct contact (for 6 hours) through another bull in the heifer shed. Estrus detection was done by bulls in T1 and T2 heifers group whereas in T0 group, heifers heat expectancy chart and visual observation of behavioural signs of estrus were used for estrus detection. Overall mean intensity of sniffing/licking, tail raising, micturition, chin resting and allowing mounting attempts during silent estrus in T0 was largely weak (88.64%) and in T1 heifers group, intensity was weak to moderate (60.05 and 34.58 %) whereas in T2 group, percentage of weak, moderate and intense was 38.5 %, 27.0 % and 34.4 % respectively. The per cent mean intensity of estrus behaviour in second estrus was weak to moderate (71.875 and 28.12) in T0, whereas in T1 group, intensity was largely weak to moderate (42.9 % and 41.3%) and intensity of cardinal signs of estrus in T2 was mostly moderate to intense in nature (31.9 % and 57.7%). It can be concluded that bull biostimulation of Sahiwal heifers through direct contact plus fenceline contact was more effective in increasing estrus behaviour intensity as compared to the only fenceline contact. Most prominent cardinal symptoms of estrus in biostimulated as well as non-biostimulated Sahiwal heifers were sniffing and licking, micturition, tail raising, allowing mounting attempts and chin resting.

Differential effects of androgens, estrogens and socio-sexual context on sexual behaviors in the castrated male goat

The behavioral and endocrine activation of sexual behaviors exhibited by male goats, especially self-enurination (SE), is poorly understood. In the first experiment, to assess the influence of socio-sexual context on SE in bucks, the effects of distance from does, the presence of estrous versus non-estrous does and the presence of another buck on SE and courtship frequencies of intact male goats (bucks; n = 12) were tested using a unique behavior test apparatus. For experiments 2 and 3, to test the relative contributions of sex steroid hormones and socio-sexual context on SE, castrated male goats (wethers; n = 20) were randomly divided into five groups and injected for seven weeks with one of the following: 25 mg testosterone propionate (T), 25 mg dihydrotestosterone propionate (DHT), 100 μg estradiol benzoate (E), 100 μg E and 25 mg DHT (E + DHT), or oil (CON). The effects of these treatments on frequency of SE and courtship were assessed using the behavior test apparatus (social scenarios) adapted from the findings in experiment 1. In one scenario, a wether could observe (from 4.6 m) a buck and estrous female (doe) together in a wire mesh holding pen. In a different scenario, the wether could observe (from the same distance) a buck that could only court the estrous doe through a wire mesh barrier. Finally, to observe the effects of steroid treatment on mounting and ejaculation frequencies, in addition to SE and courtship, each wether was placed in a pen with an estrous doe for 10 min. After a five-week, treatment-washout period, wethers were randomly assigned to different treatment groups and retested. In experiment 1, bucks that were distanced from females displayed more SEs than those with fence-line contact, while those with fence-line contact displayed more bouts of courtship (P < 0.05). In experiments 2 and 3, courtship frequencies displayed in all three scenarios were greater than CON only for groups exposed to estrogen directly or via aromatization (T, E + DHT, E; P < 0.05). Frequencies of SE exhibited during behavior tests in which the wether was watching were greater than CON only for androgen-treated groups (T, E + DHT, DHT; P < 0.05). In contrast, when the wether was free to interact with the female, only the DHT group displayed SE at a higher frequency than CON (P < 0.05). Treatment had no effect on mount frequencies in this test scenario, however ejaculation frequencies were highest for T and E + DHT (P < 0.05). These studies suggest that the courtship behaviors of the male goat are estrogen-dependent. However, SE appears to be activated by androgens. It was also demonstrated that social context contributes as much to behavior expression as steroid treatment, as in social scenario 2 some sexual behaviors were displayed in similar frequencies across groups, despite differing sex steroid treatments.