Nutritional controls of beef cow reproduction

Abstract

The livestock industry and animal scientists have long recognized the importance of proper nutrition for cattle to achieve reproductive success. Timely resumption of estrus following parturition is a major milestone that a cow must reach for optimal reproduction. Dynamic interplay among all strata of the hypothalamo-hypophyseal-ovarian axis occurs during the cow's transition from postpartum anestrus to reproductive competence. The reproductive axis integrates a milieu of nutritionally related signals that directly or indirectly affect reproduction. Directing nutritional inputs toward anabolic processes is critical to stimulating key events that promote reproductive success. Although prepartum and postpartum energy balance are the most important factors affecting duration of the postpartum interval to first estrus in beef cows, other nutritional inputs likely impinge on the hypothalamo-hypophyseal-ovarian axis to influence reproduction. For example, feeding fat to beef cows for approximately 60 d before calving may improve pregnancy rates in the upcoming breeding season. Supplementing postpartum diets with lipids high in linoleic acid can impede reproductive performance of beef cows. Precise mechanisms through which nutritional inputs mediate reproduction have not yet been fully elucidated. Scientists investigating nutritional mediators of reproduction, or how nutritional inputs affect reproduction, must be cognizant of the interactions among nutrients and nutritional cues responsible for mediating reproduction.

Nutrient restriction during late gestation reduces milk yield and mammary blood flow in lactating primiparous beef females

“…The reduction in nutrients partitioned to milk production, while negative for the calf, was likely of benefit to the dam and her chances of remaining in the herd the subsequent year. Previously nutrient restricted dams partitioned nutrients to compensatory maternal growth and replenishing basal adipose reserves instead of towards maximal milk production ( Redifer et al, 2024 ), which likely allowed them to prioritize resumption of estrus and fertility ( Randel, 1990 ; Hess et al, 2005 ) and allowed for acceptable reproductive performance ( Redifer et al, 2024 ). In a production setting, improved postpartum nutrition may not occur during droughts or times of poor forage nutrient availability.…”

Metabolic imprinting in beef calves supplemented with creep feeding on performance, reproductive efficiency and metabolome profile

“…Distinct metabolic variations among the animals emerged on day 360, highlighting pathways related to energy and glucose utilization. This metabolic insight is particularly crucial as the primary fuel source used by the central nervous system which plays a major role in the release of GnRH 58 . Notably, a prominent metabolic pathway that warrants attention is the malate-aspartate shuttle.…”

Development of an efficiency ranking system for beef cows and effects on feed intake, ruminal fermentation, NDF turnover, and apparent total tract digestibility

“…Rump fat depth was used instead of BCS given the quantitative nature of rump fat and the fact that rump fat and BCS are positively correlated and both indicative of body fat reserves (Looper et al 2010). Past research has indicated that a greater BCS at calving has been reported to hasten the postpartum interval (Osoro and Wright 1992;Hess et al 2005). Rump fat also received the greatest weighting in the current scoring system, as it was assumed to be a response directly impacted by nutrient intake and utilization by the cow under extensive winter grazing conditions.…”

“…Cows that calve earlier in the current calving season tend to also calve earlier in the following year, are older when they are first diagnosed as open, stay in the herd longer, and wean calves that are older and heavier (MacGregor and Casey 1999; Cushman et al 2013). Others have suggested using the calving interval as an indicator (Hess et al 2005); however, the use of the calving interval prevents the selection of cows within a single season. The third component of the efficiency selection was calf weaning weight when represented as a percentage of the dam's body weight.…”

“…Maintenance of, and the trajectory for, body condition score (BCS) as parturition approaches and in early lactation impact the duration of the postpartum interval. Cows that approach parturition with an adequate BCS have a shorter postpartum interval than those that lose body condition as parturition approaches (Osoro and Wright 1992;Hess et al 2005). Therefore, measures of efficiency for the cow-calf sector should include the aforementioned factors as they affect lifetime productivity and profitability (Rahnefeld et al 2011;Scholljegerdes and Summers 2016;Snelling et al 2019;Broleze et al 2020).…”