Fonte alternativas de compostos nitrogenados na alimentação de vacas F1 (H/Z) em lactação

Abstract

This work aimed to evaluate different sources of nitrogen compounds, such as soybean meal, sunflower meal, detoxificated castor bean meal and urea in diets of lactating crossbred cows on intake, digestibility of nutrients, production and feeding behavior. The experiment was carried out at the Experimental Farm UNIMONTES - Janaúba-MG. We used eight F1 Holstein/Zebu cows. The experimental design was two 4 x 4 Latin squares, consisting of four animals, four treatments and four experimental periods. We used 4 experimental diets, one for every source of nitrogen compounds (soybean meal, sunflower meal, detoxificated castor bean meal and urea), with sorghum silage as roughage base of diets. The experiment lasted 72 days, divided into four periods of 18 days. During the last four days of each period, milk yields per cow were recorded, samples of feed were collected, leftovers and feces for chemical analyzes and rumen incubation. Cows were subjected to visual observation to assess the feeding behavior after the adjustment period of each experimental period for two consecutive days. Ther was significant effects (P< 0.05) by source of nitrogen compound used in the diet. The total apparent digestibility of dry matter and non-fiber carbohydrates were not affected (P> 0.05) by food. There was effect (P< 0.05) for all diets. There was no difference (P> 0.05) for the variables feeding time, rumination time, idle time, number of periods of feeding, ruminating and idle, duration of feeding, ruminating and idle due to diet. There was no effect (P> 0.05) of the diet as for time of chews per bolus, number of chews per bolus, number of chews per minute, number of chews per day, number of ruminated boli per day, total chewing time for type of protein source used. However, time of intake of neutral detergent fiber (min/kg), the feed efficiency of dry matter and rumination efficiency of dry matter were influenced (P<0,05) by the diet used, and sunflower meal showed lower results. The times of dry matter intake, dry matter rumination, rumination of neutral detergent chewing of fiber, dry matter, chewing of neutral detergent fiber, feed efficiency of neutral detergent fiber and rumination efficiency of neutral detergent fiber were not changed (P> 0.05) by the protein source in the diet. Diets with different sources of nitrogen compounds did not alter times of feeding, idle and chewing. However, the efficiency of feeding and rumination of dry matter were influenced by the type of food used in the diet, and the sunflower meal showed the lowest results. The use of alternative sources of nitrogen compounds, such as soybean meal, urea, sunflower meal and, detoxificated castor bean meal in feeding of lactating crossbred cows, can be a viable alternative, since it does not alter milk production. Diets containing urea and detoxificated castor bean meal had a greater appreciation of economic benefit in this experiment compared to diets with soybean and sunflower meal, in feeding of F1 Holstein x Zebu cows.