Meta-analysis of the effects of prepartum dietary protein on performance of dairy cows

Abstract

The objectives were to review the published literature and use meta-analytic methods to determine the effects of dietary protein fed prepartum on productive performance of dairy cows. The hypothesis was that responses to dietary protein prepartum would differ between nulliparous and parous cows, and performance would be maximized at a greater protein supply in nulliparous than in parous cows. The literature was systematically reviewed, searching randomized experiments in which the prepartum dietary content or degradability of protein was manipulated. Twenty-seven experiments including 125 treatment means and 1,801 cows were included in the meta-analysis. Of those, 8 experiments with 27 treatment means reported responses for 510 nulliparous cows. Data collected included the ingredient composition and chemical analyses of prepartum diets, parity group, and means and respective measures of variance for productive responses. Mixed model meta-analysis was conducted and statistical models investigated the effects of dietary crude protein (CP) or supply of metabolizable protein (MP) prepartum on performance. Supply of MP was predicted using the National Research Council Nutrient Requirements of Dairy Cattle (2001) model. The mean ± standard deviation and median (range) concentrations of dietary CP fed to cows prepartum were 14.4 ± 2.2 and 14.4% (8.9 to 20.9%), resulting in mean and median (range) intakes of CP prepartum of 1,720 ± 432 and 1,734 g/d (745 to 2,482 g/d). Predicted prepartum supply of MP averaged 822 ± 157 in nulliparous cows, ranging from 517 to 1,094 g/d, and 1,146 ± 316 in parous cows, ranging from 463 to 1,733 g/d. Increasing prepartum CP content or predicted supply of MP improved postpartum dry matter intake in nulliparous cows, but increasing prepartum CP content reduced prepartum dry matter intake in parous cows. Yields of milk and fat-corrected milk increased with increasing prepartum supply of MP in nulliparous but not in parous cows. Yields of fat and protein increased in nulliparous cows with increased CP content or supply of MP. Alternatively, in parous cows, yield of milk fat was not influenced by supply of MP but responded quadratically to dietary CP content and was maximized at approximately 14% CP. Dietary CP had no effect on protein yield in parous cows, but increasing the supply of MP improved protein yield only in cows from experiments with >36 kg/d of milk production, whereas MP supply had no effect on protein yield of parous cows from experiments with <28 kg/d of milk production. Performance of dairy cows was responsive to prepartum supply of MP and nulliparous benefited from diets with increased MP intake. Based on current results, production responses for nulliparous cows increased linearly up to the maximum MP intake of 1,100 g/d observed in the study, whereas for parous cows, only yield of milk protein in cows producing more than 36 kg of milk/d was influenced by supplying more than 800 g/d of MP.

ADSA Foundation Scholar Award: New frontiers in calf and heifer nutrition—From conception to puberty

“…The current NRC (2001) model reasonably predicts the MP requirement for conceptus development during late gestation (Bell, 1995); however, the model likely underestimates late-gestation MP requirements because it does not consider the MP required for mammogenesis (~120 g of MP/d; Bell et al, 2000), consequently causing a late gestation MP deficit. A recent meta-analysis validated this concept for primiparous heifers, demonstrating linearly improved production responses when heifers were fed up to 1,100 g of MP/d during late gestation (Husnain and Santos, 2019). More conservative responses were reported with multiparous cattle (Husnain and Santos, 2019), suggesting that MP requirements may be adequately modeled for lategestation multiparous cows.…”

“…A recent meta-analysis validated this concept for primiparous heifers, demonstrating linearly improved production responses when heifers were fed up to 1,100 g of MP/d during late gestation (Husnain and Santos, 2019). More conservative responses were reported with multiparous cattle (Husnain and Santos, 2019), suggesting that MP requirements may be adequately modeled for lategestation multiparous cows. However, it is crucial to acknowledge that this meta-analysis focused on cow production parameters without evaluating the influence of maternal MP supply on calf performance.…”

Management-related factors in dry cows and their associations with colostrum quantity and quality on a large commercial dairy farm

“…A short stay in the close-up pen (10 d vs. 21 d), however, resulted in reduced colostrum quantity (Farahani et al, 2017). It is possible that optimum length of exposure to a prepartum diet differs between nulliparous heifers and parous cows, as nulliparous heifers have an increased demand for MP (Husnain and Santos, 2019).…”

Effect of Different Combinations of Dietary Vitamin A, Protein Levels, and Monensin on Inflammatory Markers and Metabolites, Retinol-Binding Protein, and Retinoid Status in Periparturient Dairy Cows

“…The meta-analysis by Husnain and Santos [ 21 ] showed that greater protein levels in prepartum diets could also increase pre- and postpartum intake and more milk, milk fat, and milk protein in primiparous cows. However, there is no evidence in the literature about a diet that combines the effects of a greater protein, vitamin A as a booster to the immune system, and monensin as an energy metabolism modulator.…”