Effects of Two Levels of Dietary Energy Content on Milk Production and Serum Metabolites in Early Lactation Temperate Crossbred Dairy Cows Fed Guinea Grass (Megathyrsus maximus) Based Diets

The current study investigated the association of two levels of metabolizable energy (ME) content on milk production, composition, and blood metabolites of temperate crossbred (Jersey x Frieician) dairy cows fed with Guinea grass (Panicum maximum) and concentrates (50:50 on a DM basis) based total mixed ration (TMR). Twelve multiparous temperate crossbred dairy cows were randomly allocated to each dietary treatment (n=6) in a randomized block design. The required energy diet (RE) was predicted to supply the recommended level (100%) of ME, and the high energy diet (HE) was predicted to supply 10% more than the recommended level (110%) of the daily ME requirements of the dairy cows. Dry matter intake, body weight, and milk yield were recorded, and feed and blood samples were obtained for proximate and blood metabolite analysis during the 14 weeks experimental period. No treatment effects were observed (P>0.05) on BW, milk fat, SNF, protein, and milk urea nitrogen or on blood metabolites such as serum non esterified fatty acids, beta-hydroxy butyric acid, Albumin, Ca and P. Compared to the cows fed with RE, HE diet fed cows had high (P<0.05) dry matter intake at 4, 10, 12, and 14 weeks but dietary treatment had no effect on dry matter intake (P>0.05) at 2, 6, and 8 weeks of the experimental period. Until the 4th week of lactation, dietary treatment had no effect (P>0.05) on milk yield, but from the 4th to the 14th week, cows fed with HE had a higher (P<0.05) milk yield than those fed with RE. Thus, the cumulative milk yield of the cows fed with HE were higher (P<0.05) than that of cows fed with RE from the 10th to 14th weeks of lactation. It was concluded that the milk yield of temperate crossbred dairy cows fed diets based on Guinea grass can be enhanced by incorporating high energy content into the diet.