Devices (IceTag ® ActivityMonitor) using accelerometer technology to determine the behaviour of c... more Devices (IceTag ® ActivityMonitor) using accelerometer technology to determine the behaviour of cows (proportion of time lying, standing, active and step count) were attached to 15 cows (2 per cow) and validated between devices and against observed behaviour. For standing and active, 95% of paired (within cow) one minute data points were within 7% points, 95% of the lying data points were within 1% point, and 95% of stepping data were within 3 steps. The device recorded 100% of lying bouts within ±1 minute of visually observed data. In a second experiment, 16 lactating dairy cows were fitted with IceTag ® s and the relationship between behaviour profiles and oestrus evaluated. Blood progesterone concentration and twice- daily visual observations were used to identify precisely ovulation events and four algorithms, based on active and lying behaviour, were developed. A 24 hour rolling mean of activity and a slope threshold of 0.2 calculated for either the previous 10 hours (Activity2...
The working hypothesis was that postpartum anovulatory intervals (PPAI) of grazing dairy cows are... more The working hypothesis was that postpartum anovulatory intervals (PPAI) of grazing dairy cows are shortened by inclusion of concentrates that increase the nonstructural carbohydrate content of the transition diet. Dietary treatments were arranged as a 2x2 factorial, with 68 multiparous cows assigned to isoenergetic diets (114 MJ of metabolizable energy/cow per day) of pasture and pasture silage (PreP) or pasture and pasture silage supplemented with 3 kg of dry matter/cow per day a corn- and barley-based concentrate for 36 d prepartum (PreC). After calving, cows within each prepartum diet group were managed on isoenergetic diets (179 MJ of metabolizable energy/cow per day) of either pasture and pasture silage (PostP) or pasture and pasture silage supplemented with 5 kg of dry matter/cow per day a corn- and barley-based concentrate (PostC) for at least 35 d and until reestablishment of ovulatory cycles. Relative to day of calving (d 0), blood samples were collected at least weekly fro...
Reproduction and milk production responses were compared between dairy cows offered a high (HPA; ... more Reproduction and milk production responses were compared between dairy cows offered a high (HPA; n=453 in 4 replicates) or low (LPA; n=317 in 3 replicates) pasture allowance for the first 14 d after the planned start of mating (d 0 of experiment) in 2 seasonal, pasture-based dairy herds. Estimated pasture dry matter intake (DMI) between d -1 and 13 were 14.3+/-2.8 and 8.0+/-1.7kg of DM/cow per day for HPA and LPA cows, respectively. The LPA cows produced 22% less energy-corrected milk during the 14-d feeding treatment period, and milk yield remained less in LPA cows at d 53 despite all cows receiving pasture allowances to support DMI of 16kg of dry matter/cow per day from d 14 onwards. The 3-wk submission rate (percentage of cows inseminated at least once from d 0 to 20) and the 3- and 6-wk pregnancy rates of LPA cows (88, 45, and 71%, respectively) were lower than those of HPA cows (94, 53, and 78%, respectively), but conception rates to first (50%) or second (47%) service and fina...
Two experiments were performed to evaluate the efficacy of a progestin-based estrus synchronizati... more Two experiments were performed to evaluate the efficacy of a progestin-based estrus synchronization program that incorporated the use of estradiol at the initiation of progestin treatment and at 48 h after progestin withdrawal (Exp. 2). In Exp. 1, cyclic, lactating dairy cows (n = 112) were assigned to receive either 1 (1mg) or 2 (2mg) mg of estradiol benzoate via an i.m. injection on d -9 (d 0 = initiation of the breeding season). All cows received an intravaginal progesterone-releasing insert (IPI; CIDR-B) on d -9. On d -2, the IPI was withdrawn and all cows were administered 500 microg of cloprostenol sodium. Beginning on d 0, cows were bred by AI upon detection of estrus. Estrus was observed in similar proportions of cows in each treatment during the first 6 d of AI (90% across treatments), but the interval to estrus was shorter (P < .05) in 1mg (1.26 +/- .18 d) than in 2mg (1.77 +/- .18 d). Conception and pregnancy rates did not vary among treatments; however, cows in estrus...
Inductions are an animal welfare issue and regulations aim to achieve <2% inductions on a nati... more Inductions are an animal welfare issue and regulations aim to achieve <2% inductions on a national basis by 2010. There is a need to assess the longer-term impacts of alternative reproduction management strategies on farm economics and their success in solving the problem of poor reproductive performance. Dexcel's Whole Farm Model was calibrated against observed data from Lincoln University Dairy
Post-partum uterine inflammation (endometritis) in the dairy cow is associated with lower fertili... more Post-partum uterine inflammation (endometritis) in the dairy cow is associated with lower fertility at both the time of infection and after the inflammation has resolved. We hypothesized that aberrant DNA methylation may be involved in the sub-fertility associated with uterine inflammation. The objective of this study was to characterize genome-wide DNA methylation and gene expression in the endometrium of dairy cows with sub-clinical endometritis (SUI). Endometrial tissues were obtained at 29 days post-partum (n=12) and microarrays were used to characterize transcription and DNA methylation. Analyses revealed 1,856 probes differentially expressed in animals with SUI (n=6), compared with controls (NUI, n=6, P<0.05, Storey Multiple testing correction) and 2,976 probes with significant correlation between gene expression and bacteriology score. No significant associations among DNA methylation and gene expression were detected. Analysis of transcription data using GeneGo Metacore a...
Proceedings of the Eighth International Symposium on Reproduction in Domestic Ruminants, 2009
Estrous synchronization and timed ovulation programs that permit AI at a predetermined time (time... more Estrous synchronization and timed ovulation programs that permit AI at a predetermined time (timed AI) rather than as determined by detection of spontaneous estrus are requisite for increased adoption of AI in the beef cattle industry. In the past two decades, significant progress has been achieved in developing programs that synchronize ovulation to address this need. While this progress has been driven by a multitude of fundamental discoveries in reproductive biology, the greatest impact in the past two decades has been the result of enhanced understanding of the pattern of ovarian follicle growth in cattle and development of technologies to coordinate growth and ovulation of the dominant follicle. At present, estrous synchronization programs that result in acceptable timed AI pregnancy rates are available for beef cattle. The capacity to control growth of the dominant follicle and evaluate the impact of various approaches on fertility has resulted in greater understanding of the factors that influence maturity of ovulatory follicles. Modifications to the standard industry breeding programs, with the aim of lengthening and/or increasing the gonadotropic stimulus and estradiol production by preovulatory follicles, have been shown to substantially increase timed AI pregnancy rate in beef cattle. Associations between characteristics of follicular development and fertility have surfaced from application of estrous and ovulation synchronization technologies and led to investigation of the fundamental mechanisms that underlie these relationships.
The objective was to compare three diagnostic approaches for intrauterine infection and inflammat... more The objective was to compare three diagnostic approaches for intrauterine infection and inflammation: scoring of vaginal contents; quantification of percentage of nucleated cells that were polymorphonuclear leukocytes (PMN) following endometrial cytology; and intra-uterine bacteriology. Dairy cows (n = 303) were examined twice, Days 28 (D28) and 42 (D42), where Day 0 = day of calving. Associations between gross vaginal inflammation scores, uterine cytology, and bacteriology, and subsequent reproductive performance were examined using multivariable models. There was fair agreement at D28 (Kappa = 0.29), but only slight agreement at D42 (Kappa &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.15), between PMN% and gross vaginal inflammation score. Cows were categorized as having PMN% in the highest quartile (H), or not (L), at both D28 and D42; therefore, cows were categorized as PMNLL, PMNLH, PMNHL, or PMNHH. Cows in the highest PMN% quartile at both time periods were slower to conceive (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) than those in all other quartiles (mean ± SEM 32.2 ± 2.3, 37.0 ± 5.3, 40.8 ± 4.1, and 55.3 ± 7.3 d from start of breeding to conception for PMNLL, PMNLH, PMNHL, and PMNHH PMN% cows, respectively). Milk yield was greater (P = 0.001) in cows in the lower quartiles for PMN% at D28 and D42 (i.e., PMNLL) than those in the PMNHH and PMNHL categories, with PMNLH intermediate (P = 0.001). We concluded that PMN% was a better predictor of reproductive performance than either intra-uterine bacteriology or gross vaginal inflammation score. Cows in the highest quartile for PMN% at both D28 and D42 had lower pregnancy rates, took longer to conceive, and had a lower milk yield than those in the lower PMN% categories.
Devices (IceTag ® ActivityMonitor) using accelerometer technology to determine the behaviour of c... more Devices (IceTag ® ActivityMonitor) using accelerometer technology to determine the behaviour of cows (proportion of time lying, standing, active and step count) were attached to 15 cows (2 per cow) and validated between devices and against observed behaviour. For standing and active, 95% of paired (within cow) one minute data points were within 7% points, 95% of the lying data points were within 1% point, and 95% of stepping data were within 3 steps. The device recorded 100% of lying bouts within ±1 minute of visually observed data. In a second experiment, 16 lactating dairy cows were fitted with IceTag ® s and the relationship between behaviour profiles and oestrus evaluated. Blood progesterone concentration and twice- daily visual observations were used to identify precisely ovulation events and four algorithms, based on active and lying behaviour, were developed. A 24 hour rolling mean of activity and a slope threshold of 0.2 calculated for either the previous 10 hours (Activity2...
The working hypothesis was that postpartum anovulatory intervals (PPAI) of grazing dairy cows are... more The working hypothesis was that postpartum anovulatory intervals (PPAI) of grazing dairy cows are shortened by inclusion of concentrates that increase the nonstructural carbohydrate content of the transition diet. Dietary treatments were arranged as a 2x2 factorial, with 68 multiparous cows assigned to isoenergetic diets (114 MJ of metabolizable energy/cow per day) of pasture and pasture silage (PreP) or pasture and pasture silage supplemented with 3 kg of dry matter/cow per day a corn- and barley-based concentrate for 36 d prepartum (PreC). After calving, cows within each prepartum diet group were managed on isoenergetic diets (179 MJ of metabolizable energy/cow per day) of either pasture and pasture silage (PostP) or pasture and pasture silage supplemented with 5 kg of dry matter/cow per day a corn- and barley-based concentrate (PostC) for at least 35 d and until reestablishment of ovulatory cycles. Relative to day of calving (d 0), blood samples were collected at least weekly fro...
Reproduction and milk production responses were compared between dairy cows offered a high (HPA; ... more Reproduction and milk production responses were compared between dairy cows offered a high (HPA; n=453 in 4 replicates) or low (LPA; n=317 in 3 replicates) pasture allowance for the first 14 d after the planned start of mating (d 0 of experiment) in 2 seasonal, pasture-based dairy herds. Estimated pasture dry matter intake (DMI) between d -1 and 13 were 14.3+/-2.8 and 8.0+/-1.7kg of DM/cow per day for HPA and LPA cows, respectively. The LPA cows produced 22% less energy-corrected milk during the 14-d feeding treatment period, and milk yield remained less in LPA cows at d 53 despite all cows receiving pasture allowances to support DMI of 16kg of dry matter/cow per day from d 14 onwards. The 3-wk submission rate (percentage of cows inseminated at least once from d 0 to 20) and the 3- and 6-wk pregnancy rates of LPA cows (88, 45, and 71%, respectively) were lower than those of HPA cows (94, 53, and 78%, respectively), but conception rates to first (50%) or second (47%) service and fina...
Two experiments were performed to evaluate the efficacy of a progestin-based estrus synchronizati... more Two experiments were performed to evaluate the efficacy of a progestin-based estrus synchronization program that incorporated the use of estradiol at the initiation of progestin treatment and at 48 h after progestin withdrawal (Exp. 2). In Exp. 1, cyclic, lactating dairy cows (n = 112) were assigned to receive either 1 (1mg) or 2 (2mg) mg of estradiol benzoate via an i.m. injection on d -9 (d 0 = initiation of the breeding season). All cows received an intravaginal progesterone-releasing insert (IPI; CIDR-B) on d -9. On d -2, the IPI was withdrawn and all cows were administered 500 microg of cloprostenol sodium. Beginning on d 0, cows were bred by AI upon detection of estrus. Estrus was observed in similar proportions of cows in each treatment during the first 6 d of AI (90% across treatments), but the interval to estrus was shorter (P < .05) in 1mg (1.26 +/- .18 d) than in 2mg (1.77 +/- .18 d). Conception and pregnancy rates did not vary among treatments; however, cows in estrus...
Inductions are an animal welfare issue and regulations aim to achieve <2% inductions on a nati... more Inductions are an animal welfare issue and regulations aim to achieve <2% inductions on a national basis by 2010. There is a need to assess the longer-term impacts of alternative reproduction management strategies on farm economics and their success in solving the problem of poor reproductive performance. Dexcel's Whole Farm Model was calibrated against observed data from Lincoln University Dairy
Post-partum uterine inflammation (endometritis) in the dairy cow is associated with lower fertili... more Post-partum uterine inflammation (endometritis) in the dairy cow is associated with lower fertility at both the time of infection and after the inflammation has resolved. We hypothesized that aberrant DNA methylation may be involved in the sub-fertility associated with uterine inflammation. The objective of this study was to characterize genome-wide DNA methylation and gene expression in the endometrium of dairy cows with sub-clinical endometritis (SUI). Endometrial tissues were obtained at 29 days post-partum (n=12) and microarrays were used to characterize transcription and DNA methylation. Analyses revealed 1,856 probes differentially expressed in animals with SUI (n=6), compared with controls (NUI, n=6, P<0.05, Storey Multiple testing correction) and 2,976 probes with significant correlation between gene expression and bacteriology score. No significant associations among DNA methylation and gene expression were detected. Analysis of transcription data using GeneGo Metacore a...
Proceedings of the Eighth International Symposium on Reproduction in Domestic Ruminants, 2009
Estrous synchronization and timed ovulation programs that permit AI at a predetermined time (time... more Estrous synchronization and timed ovulation programs that permit AI at a predetermined time (timed AI) rather than as determined by detection of spontaneous estrus are requisite for increased adoption of AI in the beef cattle industry. In the past two decades, significant progress has been achieved in developing programs that synchronize ovulation to address this need. While this progress has been driven by a multitude of fundamental discoveries in reproductive biology, the greatest impact in the past two decades has been the result of enhanced understanding of the pattern of ovarian follicle growth in cattle and development of technologies to coordinate growth and ovulation of the dominant follicle. At present, estrous synchronization programs that result in acceptable timed AI pregnancy rates are available for beef cattle. The capacity to control growth of the dominant follicle and evaluate the impact of various approaches on fertility has resulted in greater understanding of the factors that influence maturity of ovulatory follicles. Modifications to the standard industry breeding programs, with the aim of lengthening and/or increasing the gonadotropic stimulus and estradiol production by preovulatory follicles, have been shown to substantially increase timed AI pregnancy rate in beef cattle. Associations between characteristics of follicular development and fertility have surfaced from application of estrous and ovulation synchronization technologies and led to investigation of the fundamental mechanisms that underlie these relationships.
The objective was to compare three diagnostic approaches for intrauterine infection and inflammat... more The objective was to compare three diagnostic approaches for intrauterine infection and inflammation: scoring of vaginal contents; quantification of percentage of nucleated cells that were polymorphonuclear leukocytes (PMN) following endometrial cytology; and intra-uterine bacteriology. Dairy cows (n = 303) were examined twice, Days 28 (D28) and 42 (D42), where Day 0 = day of calving. Associations between gross vaginal inflammation scores, uterine cytology, and bacteriology, and subsequent reproductive performance were examined using multivariable models. There was fair agreement at D28 (Kappa = 0.29), but only slight agreement at D42 (Kappa &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.15), between PMN% and gross vaginal inflammation score. Cows were categorized as having PMN% in the highest quartile (H), or not (L), at both D28 and D42; therefore, cows were categorized as PMNLL, PMNLH, PMNHL, or PMNHH. Cows in the highest PMN% quartile at both time periods were slower to conceive (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001) than those in all other quartiles (mean ± SEM 32.2 ± 2.3, 37.0 ± 5.3, 40.8 ± 4.1, and 55.3 ± 7.3 d from start of breeding to conception for PMNLL, PMNLH, PMNHL, and PMNHH PMN% cows, respectively). Milk yield was greater (P = 0.001) in cows in the lower quartiles for PMN% at D28 and D42 (i.e., PMNLL) than those in the PMNHH and PMNHL categories, with PMNLH intermediate (P = 0.001). We concluded that PMN% was a better predictor of reproductive performance than either intra-uterine bacteriology or gross vaginal inflammation score. Cows in the highest quartile for PMN% at both D28 and D42 had lower pregnancy rates, took longer to conceive, and had a lower milk yield than those in the lower PMN% categories.
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