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 intensify 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.

Materials and 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 LP and HP diets, respectively.

Results: Although milk yield was not affected by dietary treatments, the HP diet increased milk protein and lactose contents compared with LP diet in 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 HP diet compared with LP diet. Metabolic efficiency of metabolizable protein was higher in buffaloes fed LS diet compared with HS diet. Rumen pH decreased with HS diet compared with LS diet in HP group, however, no such change was observed in LP group. Methane production was increased with LS diet compared with HS diet. Contrarily, methane production was decreased in buffaloes fed HP diet compared with those fed 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, high starch combined with high protein content can effectively improve milk protein and lactose contents while reducing the methane emission of lactating buffaloes.