Consumo, digestibilidade e comportamento ingestivo de vacas F1 Holândes/Zebu em lactação submetidas à restrição alimentar

Abstract

The objective of this study was to evaluate the intake, nutrient digestibility, milk yield and ingestive behavior of F1 Holstein x Zebu cows, in different lactation periods, submitted to feed restriction. Sixty cows were sent and the experimental design was adopted in the 5 x 3 factorial, with 5 diet supply levels and 3 lactation periods. The values of the diet offer are lower as a percentage of body weight, being: diet at will, allowing 5% of leftovers in relation to the amount of dry matter; available diets, 2.75%; 2.5%; 2.25%; 2% of body weight in dry matter. The mean values of lactation days in each experimental period evaluated and respective standard patterns were: 1st period, 50.0 ± 12.80 days; 2nd period, 111.5 ± 11.75 days; 3rd period, 183.0 ± 17.5 days. Consumption of dry matter, crude protein, neutral detergent fiber and total digestible nutrients in kg day-1 and consumption of total digestible nutrients as a percentage of the corporal weight influenced by food restriction with decreasing linear regression due to the reduction of supply levels of foods. Only the consumption of crude protein in kg day -1 did not show effect of lactation periods. Consumption of dry matter in the third lactation period was higher. There was higher consumption of neutral detergent fiber in the first lactation period. The consumption of total digestible nutrients in kg day-1 and percentage of body weight was lower in the second lactation period. Total apparent digestibility of dry matter, ethereal extract and total digestible nutrients presented a quadratic regression due to the reduction of supply levels. Total apparent digestibility of neutral detergent fiber was linearly increased with a reduction in dietary supply. A food restriction influenced the final weight, a change in weight and also a change in the condition of the people's body condition, but did not influence the final body condition score. The milk production reduced with the food restriction, presenting a linear decreasing effect. The times spent with food and regeneration decreased and with leisure increased with a reduction in diet supply levels. As for lactation periods, feeding times and rumination, in the initial period, were higher in relation to the other periods. A dietary use of dry matter and neutral detergent fiber (g hora-1) were influenced by dietary restriction, presenting increasing linear effect with a reduction in dietary supply. It is already a tool of rumination of dry matter and fiber in neutral detergent presented linear decreasing effect. In relation to the lactation and feeding periods of dry matter and neutral detergent fiber and dry matter efficiency with longer periods of time. The supply of the diet at will and the initial phase of lactation (50 ± 12.80 days) provided longer feeding and rumination time. On the other hand, the restriction of food supply implies better feed efficiencies of dry matter and of the neutral detergent fiber in grams hour-1. Reduced food restriction or consumption of dry matter and nutrients and consequently also reduced milk production. Provide improvements in diet and food efficiency, and can be adapted to reduce costs with feeding of Holstein/Zebu F1 cows.