Milk yield and quality of Holstein cows grazing on different silvopastoral systems in the high tropics

Abstract

This study evaluated the effect of different grazing systems on yield and quality of milk in Holstein cows. Four silvopastoral systems (SP) were compared, as follows: kikuyo (Cenchrus clandestinus) and ryegrass (Lolium ssp) (R); ryegrass, tree marigold (Tithonia diversifolia) and alder (Alnus acuminata) (sspR); kikuyo, tree marigold and alder (sspK); and ryegrass, kikuyo, tree marigold and alder (sspRK). The response variables were daily milk traits: yield, (PL), lactose, (L), fat, (G), and protein, (P); milk constituents of protein (% P) and fat (% G), and milk urea nitrogen (MUN) of 60 holstein cows from 1 to 6 parities. We used mixed generalized additive models with smoothed semiparametric effect for days in lactation (DEL), fixed effects of SP, number of calvings, and the random effect of lactation. According to the results, the SspR system had higher PL, L, P, and G compared with the other systems (P < 0.05), demonstrating the potential of silvopastoral systems in the high tropics.