The effect of nutritional management of the dairy cow on reproductive efficiency

The objective of this study was to identify detailed fertility traits in dairy and beef cattle from transrectal ultrasonography records and quantify the associated risk factors. Data were available on 148 947 ultrasound observations of the reproductive tract from 75 949 cows in 843 Irish dairy and beef herds between March 2008 and October 2012. Traits generated included (1) cycling at time of examination, (2) cystic structures, (3) early ovulation, (4) embryo death and (5) uterine score; the latter was measured on a scale of 1 (good) to 4 (poor) characterising the tone of the uterine wall and fluid present in the uterus. After editing, 72 773 records from 44 415 dairy and beef cows in 643 herds remained. Factors associated with the logit of the probability of a positive outcome for each of the binary fertility traits were determined using generalised estimating equations; linear mixed model analysis was used for the analysis of uterine score. The prevalence of cycling, cystic structures, early ovulation and embryo death was 84.75%, 3.87%, 7.47% and 3.84%, respectively. The occurrence of the uterine heath score of 1, 2, 3 and 4 was 70.63%, 19.75%, 8.36% and 1.26%, respectively. Cows in beef herds had a 0.51 odds (95% CI = 0.41 to 0.63, P < 0.001) of cycling at the time of examination compared with cows in dairy herds; stage of lactation at the time of examination was the same in both herd types. Furthermore, cows in dairy herds had an inferior uterine score (indicating poorer tone and a greater quantity of uterine fluid present) compared with cows in beef herds. The likelihood of cycling at the time of examination increased with parity and stage of lactation, but was reduced in cows that had experienced dystocia in the previous calving. The presence of cystic structures on the ovaries increased with parity and stage of lactation. The likelihood of embryo/foetal death increased with parity and stage of lactation. Dystocia was not associated with the presence of cystic structures or embryo death. Uterine score improved with parity and stage of lactation, while cows that experienced dystocia in the previous calving had an inferior uterine score. Heterosis was the only factor associated with increased likelihood of early ovulation. The fertility traits identified, and the associated risk factors, provide useful information on the reproductive status of dairy and beef cows.

Section: Paritysupporting

confidence: 80%

Section: Paritymentioning

confidence: 99%

Risk factors associated with detailed reproductive phenotypes in dairy and beef cows

Carthy

Berry

Fitzgerald

et al. 2014

“…What is important is that in both years of the study, cows in all treatments gained live weight and maintained or increased body condition. Furthermore, the mean BCS in all treatments was a suitable score for calving (Roche, 2006). Thus, even under the more rainy and windy weather conditions in Year 1, cows did not have to mobilise body reserves towards self-maintenance.…”

Section: Discussionmentioning

confidence: 89%

The effect of dry cow winter management system on feed intake, performance and estimated energy demand

O’Driscoll

Hanlon

Buckley

et al. 2010

This research compared three wood-chip out-wintering pad (OWP; an unsheltered OWP; a sheltered OWP (both with a concrete feed apron); and an unsheltered OWP with silage provided directly on top of the wood-chip bedding (self-feed OWP)) designs and cubicle housing with regard to dairy cow performance during the pre-partum period, and for 8 weeks post partum. Data were compared during 2 years. In Year 1, the unsheltered (space allowance 5 12 m 2 per cow) and sheltered (6 m 2 per cow) OWPs were compared with cubicle housing (n 5 49 cows per treatment). In Year 2, all three OWP designs (12 m 2 per cow) were compared with cubicle housing (n 5 24 cows per treatment, split into two replicates). Animals were dried off and assigned to treatment in the autumn, and remained there until calving in spring. Subsequently, they were managed at pasture during lactation. Outcome measures for analysis during the pre-partum period were feed intake, live weight, body condition score (BCS), heat production and heat loss, and post-partum were live weight, BCS, milk yield and milk composition. In Year 1, all cows had a similar live weight, but both pre-partum and at calving cows on the unsheltered OWP had a lower BCS than cows in cubicles ( P , 0.05). However, in Year 2, there were no differences in either live weight or BCS. In Year 1, cows in the unsheltered OWP produced less heat than in cubicles ( P , 0.05), but in Year 2, there was no treatment effect. In both years, cows in unsheltered OWPs lost more heat than cows in the sheltered OWP ( P , 0.001). Treatment had no effect on milk composition either year. However, in Year 2, cows in the self-feed OWP had higher milk yields than the other treatments ( P , 0.05). The lower BCS and heat production values in unsheltered treatments during Year 1 were probably because of higher rainfall and wind-speed values of that year. However, in both years, live weight in all treatments increased pre partum, and BCS did not decrease, indicating that unsheltered cows did not need to mobilise body reserves. Thus, OWPs could be a suitable pre-partum alternative to cubicle housing for dry dairy cows with regard to some aspects of dairy cow productive performance. However, further research should be carried out to investigate longer-term effects.

“…High milk production affects the energy metabolism, which can disturb the endocrine signaling (Roche, 2006). Altered energy metabolism in high milk yielding cows can cause decreased levels of E2 and inhibit estrous behavior (Lopez et al, 2004).…”

Section: Metabolic Disturbancesmentioning

confidence: 99%

“…Subfertility in modern dairy cows is a multifactorial problem. It involves factors like genetic improvement for milk yield, nutritional issues, disease, season, climate, housing, management and herd environment (Lucy, 2001;Roche, 2006). The mechanisms by which selection for higher milk yield can result in poorer fertility are not totally elucidated, but one cause is likely to be metabolic stress (Veerkamp et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Estrous behavior in dairy cows: identification of underlying mechanisms and gene functions

Bôer

Veerkamp

Beerda

et al. 2010

Selection in dairy cattle for a higher milk yield has coincided with declined fertility. One of the factors is reduced expression of estrous behavior. Changes in systems that regulate the estrous behavior could be manifested by altered gene expression. This literature review describes the current knowledge on mechanisms and genes involved in the regulation of estrous behavior. The endocrinological regulation of the estrous cycle in dairy cows is well described. Estradiol (E2) is assumed to be the key regulator that synchronizes endocrine and behavioral events. Other pivotal hormones are, for example, progesterone, gonadotropin releasing hormone and insulin-like growth factor-1. Interactions between the latter and E2 may play a role in the unfavorable effects of milk yield-related metabolic stress on fertility in high milk-producing dairy cows. However, a clear understanding of how endocrine mechanisms are tied to estrous behavior in cows is only starting to emerge. Recent studies on gene expression and signaling pathways in rodents and other animals contribute to our understanding of genes and mechanisms involved in estrous behavior. Studies in rodents, for example, show that estrogen-induced gene expression in specific brain areas such as the hypothalamus play an important role. Through these estrogen-induced gene expressions, E2 alters the functioning of neuronal networks that underlie estrous behavior, by affecting dendritic connections between cells, receptor populations and neurotransmitter releases. To improve the understanding of complex biological networks, like estrus regulation, and to deal with the increasing amount of genomic information that becomes available, mathematical models can be helpful. Systems biology combines physiological and genomic data with mathematical modeling. Possible applications of systems biology approaches in the field of female fertility and estrous behavior are discussed.