Combinations of cactus pear with different roughage sources on the production, chemical composition, and milk fatty acid profile of F1 Holstein/Zebu cows.

The qualities of food, mainly of animal origin, have always been of concern to consumers. It is known that the composition of animals' diets can influence the composition of the foods produced, such as milk. Thus, the objective of this study was to evaluate diets with cactus pear in combination with different forages for F1 Holstein/Zebu cows on the chemical composition and fatty acid profile of milk. Two simultaneous 4 × 4 Latin squares were used in the experimental design. Four experimental diets were used: Diet 1, sorghum silage as the only roughage; Diet 2, sorghum silage combined with cactus pear in a proportion of 50% of the roughage (dry matter basis); Diet 3, elephant grass (Pennisetum purpureum cv. Roxo) as the only roughage; and Diet 4, elephant grass combined with cactus pear in a proportion of 50% of the roughage. The roughage:concentrate ratio was 75:25. The milk urea nitrogen was higher (16.08 mg/dL) in the milk of cows fed the diet with only elephant grass than that of milk from the other diet groups. The other analyzed variables of the chemical composition of milk were not influenced by the diets. However, there was a change in the sum of the saturated and monounsaturated fatty acids. The content of C16:0 fatty acid was higher and that of C18:0 was lower in the milk of cows fed the cactus pear diets than in that of cows fed the other diets. Higher levels of oleic acid were observed in the milk of cows fed with diets containing elephant grass than those in the milk of the cows in the sorghum forage groups. Conjugated linoleic acid (CLA) was higher in the milk of cows fed cactus pear than in that of the other cows. The combination of cactus pear with elephant grass or sorghum silage in the diet did not alter the chemical composition of milk. However, it influenced the fatty acid profile.

Productivity and nutritional value of BRS capiaçu grass (Pennisetum purpureum) managed at four regrowth ages in a semiarid region.

The objective of this study was to evaluate the productivity, productive efficiency, and nutritional value of the elephant grass cultivar BRS capiaçu (Pennisetum purpureum Schum.), managed at four regrowth ages during winter in the semiarid region of northern Minas Gerais, Brazil. A completely randomized design with the elephant grass cultivar BRS capiaçu was submitted to four cut intervals (30, 60, 90, and 120 days) in the winter with ten replications, for a total of 40 plots, each with a useful area of 6 × 5 m. There was a linear increase of 76.25% (P < 0.01) in the height of BRS capiaçu grass when cut from 30 to 120 days. Green matter production (P < 0.01) and dry matter production (P < 0.01) increased daily by 1081 kg/ha and 237 kg/ha, respectively. The annual dry matter production was 72 t/ha. Efficiency in water use changed (P < 0.01) from 7.91 kg of dry matter (DM)/mm at 30 days to 57.59 kg of DM/mm at 120 days of regrowth. There was a reduction in the ash content (P < 0.01), crude protein (P < 0.01), and the total digestible nutrient content (P < 0.01) with the increase in the age of the cut. The readily soluble fraction of DM (fraction A, P < 0.01), degradation rate "c" of insoluble fraction "B" (P = 0.01), potential degradability (PD; P < 0.01), and degradability (ED; P < 0.01) decreased linearly as the regrowth age increased. Harvesting is recommended at 90 days of regrowth during the winter season in this semiarid region.