Pregnant cow nutrition and its effects on foetal weight – a meta-analysis

Abstract

AbstractThe prenatal development of cattle has influence on productive performance throughout postnatal life. The number of muscle and fat cells that the animal will have throughout its life is determined in the foetal stage and is influenced by nutrition of the pregnant cow. A systematic review and meta-analysis was performed to evaluate the effect of different energy levels (total digestible nutrient, TDN) and crude protein (CP) supplied to pregnant cows on foetal weight at 4 (FW4) and 8 months (FW8) and calf birth weight (CBW). Four studies and six trials involving 170 animals were assessed for FW4; four studies, four trials and 156 animals for FW8 and 48 studies, 125 trials and 9053 animals for CBW. High heterogeneity across studies was presented in FW4 (I2 = 94.4%), FW8 (I2 = 91.08%) and CBW (I2 = 96.9%). Dietary TDN and CP levels did not influence FW4. The FW8 was reduced by 2.24 kg when cows were fed 100% of their CP and TDN requirements (I2 = 0%), relative to those fed 70% of their requirements during the first and second trimesters. The CBW was reduced by 0.45 kg (I2 = 96.9%) when cows were fed 130% of their CP requirements relative to other dietary CP levels. When cows were fed 140% of their TDN requirements, CBW decreased by 2.71 kg (I2 = 98.3%) relative to other TDN levels. Dietary energy or CP levels fed above the requirements to pregnant cows restrict foetal development and CBW.