Effects of dietary starch and protein contents on lactation performance, blood metabolites, and methane production of Nili Ravi buffaloes

Objective: Imbalanced feeding of protein and energy in ruminants coupled with increasing concerns over low production efficiencies and high livestock emissions intensifies the feeding challenges, especially in buffaloes. This study was planned to evaluate the independent or interactive effects of dietary starch and crude protein (CP) on lactation performance, blood metabolites, and methane production of dairy buffaloes.Methods: Sixteen lactating multiparous Nili Ravi buffaloes received the following dietary treatments of low (LS) or high starch (HS) content combined with low (LP) or high protein (HP) content in a 4×4 Latin square design: 1) LSLP, 2) LSHP, 3) HSLP, and 4) HSHP. Dietary starch contents were 19.5% and 28.7% in LS and HS diets, whereas CP contents were 8.8% and 10.6% in the LP and the HP diets, respectively.Results: Although milk yield was not affected by dietary treatments, the HP diet increased milk protein and lactose contents compared with the LP diet in the HS group; however, no such increase was observed in LS group, resulting in a starch×CP interaction. Efficiencies of metabolizable protein and milk nitrogen decreased with the HP diet compared with the LP diet. Metabolic efficiency of metabolizable protein was higher in buffaloes fed the LS diet compared with HS diet. Rumen pH decreased with the HS diet compared with the LS diet in the HP group; however no such change was observed in the LP group. Methane production was increased with the LS diet compared with the HS diet. Contrarily, methane production was decreased in buffaloes fed HP diet compared with those fed the LP diet.Conclusion: These findings indicated that dietary starch interacted with CP level for milk protein, milk lactose, rumen pH, and methane production of lactating buffaloes. Overall, HS combined with HP content can effectively improve milk protein and lactose contents while reducing the methane emission of lactating buffaloes.