Cana-de-açúcar em substituição a silagem de milho em dietas para cabras leiteiras

Abstract

The objective was evaluate the effects of substitution of corn silage for canesugar in the diet of dairy goats of saanen. The thesis is composed of three chapters, the first refers to the theoretical background, and discussion of results reported in two subsequent chapters. The second chapter is the substitution effect about consumption of nutrients, production, and quality of milk, while the third reported the effect of substitution on the digestibility of nutrients, water intake and ingestive behavior of animals. In three 4x4 latin squares were distributed 12 goats. The diets were composed of 50% concentrate and 50% roughage with 0; 33.3; 66.6 and 100% replacement of corn for cane sugar. The dry matter intake (kg/day,% BW g/kgPV0, 75) showed no significant difference with increasing levels of substitution of corn for cane sugar. The intakes of other nutrients followed the behavior of consumption dry matter, except for ether extract that has decreased. Milk production and milk yield corrected for 3.5% fat was not influenced significantly as the corn silage was replaced by cane sugar. For chemical composition of milk, no significant effect was observed for the production of protein, lactose and solids, however the production of fat was lower for treatment with higher levels of substitution. As for the percentages of milk fat content and total solids were negatively affected, there was no influence to others. The physical characteristics of pH, temperature and density were not affected as the silage was replaced by cane sugar. Feed efficiency did not differ between treatments. Feed efficiency did not differ between treatments. The apparent digestibility of DM, OM, CP, EE, TC and NDF linearly decreased, while the apparent digestibility of NFC was not influenced due by the increase of cane sugar in the diets, since the coefficient of apparent digestibility of ADF behaved quadratically with the substitution of corn silage by cane sugar. Water intake by food increased linearly with increasing substitution of silage, however drinking water intake decreased. The substitution of corn for cane sugar in the diets did not influence the activities of searching for water, urination and defecation. The water intake and total water per kilogram of dry matter were not affected by increasing the inclusion of cane sugar in the diet. The time and feeding efficiency were not affected by increased substitution of corn for sugar cane. The time that animals spent ruminating and chewing increased as the sugar cane was being included in the diet, while the idle time decreased linearly. The number of ruminated boli, number of chews per time and number of ruminated boli were not influenced by the inclusion of sugar cane, but the number of chews per day increased. The sugar cane can replace corn silage in the diet of goats as a unique volume average production without altering food intake, milk production and feed efficiency, but commits the digestibility of diets and feeding behavior.