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Relationships between dietary composition and reproductive outcomes in cattle.

T. Davis

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06-23-2020

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Abstract:

T91
Relationships between dietary composition and reproductive outcomes in cattle.
T. Davis*, R. White. Virginia Tech Blacksburg, VA.

Individual experiments and recent literature summaries suggest links between reproductive outcomes and dietary composition in cattle. However, there is a risk of confounding results in previous meta-analyses focused on a single nutrient because a change in one dietary input requires changes in other nutrients. The objective of this meta-analysis was to evaluate the effects of dietary composition on reproductive efficiency in cattle. A literature search returned 41 previously published papers containing 164 treatment means that were eligible for use. For papers to be used, they needed to report reproductive outcomes, dry matter intake, experimental design details (treatments, design, number of experimental units, measurement SE or SD values, and P-values), and diets with all ingredients and inclusion percentages. Days to ovulation, pregnancy at first artificial insemination, and overall pregnancy rate were the primary reproductive outcomes of interest. Diet composition information of interest included neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), ether extract (EE), non-structural carbohydrate (NSC), lignin and starch percentages. Relationships were analyzed using linear mixed effects models with a random intercept for each study and weighted by the number of experiment units used (due to poor reporting of response variable standard errors). When diet composition information was not reported, it was estimated from commercial feed library data and reported dietary feed inclusion rates. Significant variables were identified through a backward elimination multiple regression approach. Overall pregnancy rate tended to be affected by interactions among the percentages of EE and NDF (P = 0.095), ADF and EE (P = 0.069), and CP and NSC (P = 0.023) in the diet. Days to ovulation was affected the interactions of CP and ADF (P = 0.010), CP and starch (P = 0.005), and starch and NDF (P = 0.058) in the diet. Pregnancy at first AI was not affected by the nutritional factors evaluated here. These data highlight the importance of evaluating nutrient interactions on productive outcomes, rather than focusing on the responses to a single nutrient.

Keywords: cattle, reproduction, meta-analysis.

Biography: Ty Davis originally of Fort Worth, TX had little agricultural experience growing up. However, has closed the gap between he and his peers by obtaining his BS in animal science at Oklahoma State University with a minor in agribusiness and by interning with JBS Five Rivers, JBS USA, and Gardiner Angus. He then obtained his MS at Colorado State University in Biomedical Sciences with an emphasis in Assisted Reproductive Technologies where he studied reproductive physiology. He now is a PhD student at Virginia Tech where he is studying ruminant nutrition by finding the links between nutrition and reproduction in cattle.