Productive performance of lactating Brown Swiss cows grazing on an agrosilvopastoral system in a dry tropical region in central Mexico: contribution of grass, herbaceous and woody species

Cattle production in agrosilvopastoral systems (ASPS) in the dry tropical regions of Mexico relies on forages under extensive management with limited supplementation. Information about the botanical composition of the diet (BCD) and the contribution of available forages in ASPS to cattle is scarce. The objectives of the study were to determine the BCD of lactating Brown Swiss cows, grazing on an ASPS during the dry and rainy seasons in a dry subtropical region of Mexico, and to determine the contribution of forage species to the cows dry matter intake (kg/day), crude protein (CP) (kg/day) and metabolizable energy (ME) (MJ/day) requirements. Fifteen lactating cows were monthly monitored for one year to determine the BCD by microhistological analysis, as well as its productive performance. A mixed procedure of SAS was used to determine the effects of the season as a fixed effect and cow as a random effect on animal productive performance and BCD variables. The forages in the BCD were grouped as grasses, herbaceous and woody species. During the dry season grass and woody groups represented 84.2 and 15.7% of the BCD, whereas in the rainy season grass, herbaceous and woody groups represented 57.6, 26.6, and 7.4% of the BCD, respectively. During the dry season grass and herbaceous groups contributed with 64% of the cows nutritional requirements. Whereas during the rainy season grass, herbaceous and woody groups contribution to the cows nutritional requirements was 87%. It is concluded that grass, herbaceous and woody groups contributed to DMI, CP and ME to the requirements of lactating cows grazing on an agrosilvopastoral system with seasonal differences.