Digestible Valine Requirements in Low-Protein Diets for Broilers Chicks

Abstract

Three experiments were carried out to evaluate the levels of digestible valine in diets with reduced crude protein on the performance, carcass yield and muscle fiber diameter of male broilers during the pre-starter (1 to 8 d of age), starter (9 to 21 d of age) and grower phases (21 to 42 d of age). A total of 1,080 chickens in the pre-starter phase, 900 in the starter phase and 864 in the grower phase were distributed in a completely randomized design with six treatments, consisting of a control positive diet (C+) and diets with 2 percentage points (p.p.) reduction of crude protein level and five graded levels of digestible valine (Val), with six replicates of 30, 25 and 24 birds per experimental unit, respectively. The recommended level of TID Val in the low-protein diets for broilers in the pre-starter, starter and grower stages were 1.028; 0.905 and 0.789%, respectively. The reduction of 2 percentage points of the crude protein level in diets based on corn and soybean meal impaired (p≤0.05) the feed conversion ratio in the starter and grower stages. Likewise, the reduced-protein diets decreased (p≤0.05) muscle fiber diameter, but did not affect (p>0.05) carcass and parts yields, or abdominal fat percentage at 42 days.

Response of broilers to supplementation of branched-chain amino acids blends with different valine contents in the starter period under summer conditions

“…These reports and our findings indicate that the maximum breast yield requires a normal-CP diet. Furthermore, the valine requirements for the proliferation of muscle cells in broiler chickens at early stages of growth may be altered by high summer temperature [ 4 , 13 ]. These discrepancies may be due to the breed and age of experimental birds, the valine- and isoleucine-to-lysine ratios [ 6 , 23 , 24 ] and the quality of the ingredients of diets or the severity and duration of high temperature [ 1 , 11 , 25 ].…”

“…However, these results are disagreement with previous some studies [6,22] in which broiler performance was positively affected by valine supplementation. The differences among the previous studies and the present study may be related to the fact that the relationships among BCAAs contribute to the differences in the AA ratios such as valine to lysine [22-24] and/or digestible valine requirements are differ for maximum performances and breast yield in broilers fed low-CP diet during the starter phase [11,13,14]. Potenç a et al [24] reported that a valine to lysine ratio of 66% is sufficient to maximize the performance of broilers from 1 to 14 d of age.…”

“…Therefore, the anti-proteolytic or anti-catabolic effect of leucine is promoted in the presence of valine and isoleucine [ 12 ]. Although feeding low-CP diets while adding more crystalline BCAAs (in particular valine and isoleucine) than that required to broiler diets during early ages has gained importance [ 6 , 11 , 13 , 14 ], the response of broilers to blends of BCAAs with different valine contents is not well defined in the hot-climatic conditions.…”

“…A reduction in FI of broilers reared in hot-climate region could change the partition and utilization of AAs in the metabolism of birds due to reduced protein intake [ 10 , 11 ]. Dietary valine has decreased the negative effect of feeding low-CP diets in broiler chickens through the beneficial effect on protein accretion and intestinal morphology [ 6 , 13 ]. Therefore, we hypothesised that during the first two weeks, the mixture of BCAAs with increased content of valine may provide an opportunity to reduce the CP of the broiler starter diet and to mitigate the effects of heat stress from summer conditions on growth performance.…”

Novel Mutation of Exon 5 Prolactin Gene in IPB-D1 Chicken

“…The structure of these amino acids was changed where valine is one of three branched-chain amino acids (the others are leucine and isoleucine) that enhance energy, increase endurance, and aid in muscle tissue recovery and repair (NCBI 2020). This group also lowers elevated blood sugar levels and increases growth hormone production in chicken (Nascimento et al 2016). The g.8096T>C changes the leucine amino acid to serine.…”