Nitrogen Metabolism in Lactating Goats Fed with Diets Containing Different Protein Sources

Abstract

This study aimed to evaluate urea excretion, nitrogen balance and microbial protein synthesis in lactating goats fed with diets containing different protein sources in the concentrate (soybean meal, cottonseed meal, aerial part of cassava hay and leucaena hay). Four Alpine goats whose mean body weight was 42.6±6.1 kg at the beginning of the experiment, a mean lactation period of 94.0±9.0 days and a production of 1.7±0.4 kg of milk were distributed in a 4×4 Latin square with four periods of 15 days. Diets were formulated to be isonitrogenous, containing 103.0 g/kg of CP, 400 g/kg of Tifton 85 hay and 600 g/kg of concentrate. Diet containing cottonseed meal provided (p<0.05) increased excretion of urea and urea nitrogen in the urine (g/d and mg/kg of BW) when compared with leucaena hay. The diets affected the concentrations of urea nitrogen in plasma (p<0.05) and excretion of urea nitrogen in milk, being that soybean meal and cottonseed meal showed (p<0.05) higher than the average aerial part of the cassava hay. The use of diets with cottonseed meal as protein source in the concentrate in feeding of lactating goats provides greater nitrogen excretion in urine and negative nitrogen balance, while the concentrate with leucaena hay as a source of protein, provides greater ruminal microbial protein synthesis.

Urea concentration in goat milk: importance of determination and factors of variability

“…In contrast, in the extensive mode of goat keeping the increase in the proportion of crude protein in the supplementary portion of the diet has no effect the milk urea concentration (Cabiddu et al, 1999;Bava et al, 2001;Todaro et al, 2005;Bonanno et al, 2008). In addition, Santos et al (2014) aimed to assess the degree of urea excretion and the synthesis of microbial proteins in Alpine goats fed a diet containing different sources of protein in the concentrate (soy, a meal composed of cotton seeds, cassava hay and alfalfa hay). These authors found the highest concentration of urea in the blood and milk in goats fed with soybeans and cotton seeds, which explains the better breakdown of protein in the rumen due to insufficient matching in carbon and nitrogen structure used by microorganisms during urea synthesis.…”

“…, reproductive traits of goats (Godden et al, 2001a;Marenjak et al, 2004;Mellado et al, 2004;Butler, 2005;Biswajit et al et al, 2011), milk processing properties (Pretto et al, 2013;Bland et al, 2015) and environmental pollution (Santos et al, 2014).…”

“…Therefore, a balanced feeding structure, balancing the actual needs of the individual, the use of alternative and cheaper sources of protein in order to reduce production cost, at the same time increasing the quantity and quality of produced milk (Santos et al, 2014). Urea serves as a good indicator of the goat's energy and protein supply.…”

Brazilian Green Propolis as a Therapeutic Agent for the Post-surgical Treatment of Caseous Lymphadenitis in Sheep

“…Regarding the levels of serum uric acid found, diets with a higher crude protein level can induce a small increase in these levels (42). Varying feed composition, mainly by considering different batches of silage supplied during the experiment, could result in a small increase in uric acid levels in the second, third, and fourth weeks.…”

Ingestive Behavior of Ovine Fed with Marandu Grass Silage Added with Naturally Dehydrated Brewery Residue

“…In such context, among the alternatives for yielding of industrial byproducts animal feeding shows great potential [ 4 – 6 ], since the increase in prices of vegetal supplementation used for animal feeding has aroused great interest by the yielding of nonconventional food. However, so that the correct use of such byproducts be performed, it is necessary to verify nutrition adequacy of such ingredients [ 2 , 7 ]. This is important, for the correct formulation of diets for animals goes beyond fulfilling nutrition needs, including the quality of final product and fulfilling the expectations of consumers.…”