The aim of this study was to evaluate the effect of the manner in which diet is supplied and spineless cactus forage is processed on intake, nutrient digestibility, milk production and composition, concentration of plasma urea nitrogen (PUN) in the milk urea nitrogen (MUN) and production of microbial protein in Holstein cows in lactation. Eight cows (453 ± 75.8 kg) yielding 14 kg milk/day were allotted to a factorial design, with two manners of cactus processing (knife-chopped or forage machine) and two diet supplies (separate concentrate or total mixed ration). Intakes of dry matter, organic matter, neutral detergent fiber and total digestible nutrients were lower when cactus was knife-chopped. Digestibility, milk production and fat and protein yield did not change according to the manner diet was supplied neither by forage cactus processing. Average milk production was 14.8 kg/day for knife-chopped cactus and 14.6 kg/day for cactus chopped in forage machine and 14.8 kg/day when cactus was given in separate concentrate and 14.5 kg/day when it was given in total mixed ration. However, fat content was lower (36 g/kg) for knife-chopped cactus fed cows. Purine derivatives and concentrations of N-ureic were not influenced by the manner in which diet was supplied neither by the forage cactus processing. Means observed for efficiency of microbial protein synthesis (98.9 g/kg TDN), PUN concentrations (21.3 mg/dL) and MUN (18.2 mg/dL) were similar for cactus processing and for the manner in which diet was supplied. Forage-machine cactus processing improves dry matter intake and total mixed ration supply avoids selectivity.
milk production and composition; Opuntia fícus indica Mill; purine derivatives; semi-arid; total mixed ration
