Effect of slow release urea in sheep feed on intake, nutrient digestibility, and ruminal parameters

Abstract

This study aimed to evaluate the inclusion of 0.0%, 0.4%, 0.8%, and 1.2% slow release urea (SRU) in sheep feed on the intake and total digestibility coefficient (DC) of nutrients and ruminal parameters of sheep living in tropical regions. Four sheep with a body weight (BW) average of 30.8 ± 1.7 kg were assigned to a Latin square design. The animals were placed in metabolic cages and received two meals a day. Intake data and DC of nutrients of the sheep were subjected to analysis of variance and differences were tested using a regression equation to 5% probability. The inclusion of 0.0%, 0.4%, 0.8%, and 1.2% SRU in sheep feed did not change (p > 0.05) the intake of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral or acid detergent fiber (NDF, ADF), total carbohydrates (TC), and non-fibrous carbohydrate (NFC) expressed in g animal -1 day -1 , g (kg 0.75 ) -1 , and % BW. The mean values of 3.04%, 2.82%, 0.41%, 0.07%, 1.36%, 0.87%, 2.31%, and 1.00% of BW were obtained for the intake of DM, OM, CP, EE, ANF, ADF, TC, and NFC, respectively. The inclusion of 0.0%, 0.4%, 0.8%, and 1.2% of SRU in sheep rations had a quadratic manner (p<0.05) the DC of DM and CP, with maximum values of 69.67% and 63.59%, respectively, for 0.51% and 0.66% levels of SRU inclusion in the experimental diets. The pH of the rumen fluid did not vary (p > 0.05) for different levels of inclusion of SRU in the feed. However, the pH of the rumen fluid did differ (p<0.05) in relation to time (T) after feeding for all experimental diets. The inclusion levels of SRU in sheep feed did not affect (p>0.05) the concentration of ammonia nitrogen (NH 3 -N) of the rumen fluid, but there was a quadratic effect (p < 0.05) with relation to T for all experimental diets. Thus, we conclude that the inclusion of 0.66% SRU provides the best digestibility value of CP and is the appropriate value for the digestion of DM. The inclusion of up to 1.2% of SRU in sheep rations did not change the intake of nutrients and ruminal parameters. ResumoObjetivou-se avaliar a inclusão de 0,0%; 0,4%; 0,8% e 1,2% de ureia de liberação lenta (ULL) na alimentação de ovinos em região tropical sobre o consumo e o coeficiente de digestibilidade total (CD) dos nutrientes e parâmetros ruminais. Foram utilizados quatro ovinos com peso corporal (PC) médio de 30,8 ± 1,7 kg, distribuídos em um delineamento em quadrado latino. Os ovinos foram alocados em gaiolas de metabolismo e receberam duas refeições por dia. Os dados de consumo e CD dos nutrientes dos ovinos foram submetidos à análise de variância e as diferenças observadas foram testadas com utilização de equação de regressão a 5% de probabilidade. A inclusão 0,0%; 0,4%; 0,8% e 1,2% de ULL na alimentação de ovinos não alterou (p>0,05) o consumo de matéria seca (MS), matéria orgânica (MO), proteína bruta (PB), extrato etéreo (EE), fibra em detergente neutro (FDN) e ácido (FDA), carboidratos totais (CHT) e carboidratos não fibrosos (CNF) expressos em g animal -1 dia -1 , g (kg 0,75 ) -1 e %PC. Os va...

Effect of slow release urea in sheep feed on nitrogen balance

“…The inclusion of SRU in the feed of ruminants containing fast-fermenting carbohydrates can improve the synthesis of microbial protein (BRODERICK et al, 2009), because of the synchronization of energy and protein sources, consequently improving the fermentation environment (GALO et al, 2003), DM intake, and nutrient digestion. Another fact that corroborates the data obtained for the NI is the CP intake of the sheep fed with 0.0%, 0.4%, 0.8%, and 1.2% SRU (GERON et al, 2016), which presented an average intake of 127.97 g CP animal day -1 . Some studies using SRU to replace the traditional sources of protein in the ruminant diet have been published (SOUZA et al, 2010;SANTOS et al, 2011;SANTINO, 2013).…”

“…According to Kozloski (2002), Moreno et al (2010), and Geron et al (2015a), part of the reduction in the FN levels can be due to a reduction in the inflow of fermentative carbohydrates to the large intestine, which reduces microbial synthesis in this location and, consequently, causes a lower excretion of microbial protein and total nitrogen. This was observed by Geron et al (2016), who found that inclusion of 0.0%, 0.4%, 0.8%, and 1.2% SRU in sheep feed had a quadratic effect on the coefficients of digestibility of DM and CP, consequently reducing the amount of fermentable substrate that reached the small intestine. In According to Kozloski (2002), Moreno et al (2010), and Geron et al (2015a), part of the reduction in the FN levels can be due to a reduction in the inflow of fermentative carbohydrates to the large intestine, which reduces microbial synthesis in this location and, consequently, causes a lower excretion of microbial protein and total nitrogen.…”

“…If urea is in excess in the blood circulation only part of it is recycled, via the saliva and the rumen wall, and goes back to the rumen, whereas the rest is excreted in the urine, causing endogenous losses of nitrogen (KOZLOSKI, 2002;CARVALHO et al, 2010). This was shown by Geron et al (2016) who, when evaluating the inclusion of SRU in sheep feed, observed a quadratic behavior with a point of maximum digestibility of 69.92% for DM and 63.55% for CP estimated for the levels of inclusion of 0.50% and 0.70% SRU. These data are in agreement with the data obtained indicating that SRU in sheep feed at a range of 0.70 to 0.80% provides the best utilization of N in relation to urinary and metabolic losses.…”

“…If urea is in excess in the blood circulation only part of it is recycled, via the saliva and the rumen wall, and goes back to the rumen, whereas the rest is excreted in the urine, causing endogenous losses of nitrogen (KOZLOSKI, 2002;CARVALHO et al, 2010). This was shown by Geron et al (2016) Nevertheless, the amount of UN is related to the content of CP in the diet, with increased excretion of urea via the urine when NI increases, as this results in higher production of urea in the liver, whereas a low NI leads to a decrease in the excretion of urea via the urine to maintain the plasma urea pool, under Nevertheless, the amount of UN is related to the content of CP in the diet, with increased excretion of urea via the urine when NI increases, as this results in higher production of urea in the liver, whereas a low NI leads to a decrease in the excretion of urea via the urine to maintain the plasma urea pool, under homeostatic physiological control (ZEOULA et al, 2006). However, Geron et al (2016) demonstrated that the inclusion of up to 1.2% SRU in sheep feed does not alter the intake of DM and CP in feeds with a CP content of 13.5%.…”

“…A study conducted by Geron et al (2016) evaluated the inclusion of 0.0%, 0.4%, 0.8%, and 1.2% SRU in sheep feed on intake and digestibility of nutrients and ruminal parameters. It showed that inclusion of SRU did not alter nutrient intake and ruminal parameters; however, it caused a change in the digestibility coefficient of DM and CP.…”