Valine needs of male broilers from 42 to 56 days of age

Functional role of branched chain amino acids in poultry: a review

This review provides insight into the effects of the branched-chain amino acids (BCAA: leucine, isoleucine, and valine) on the growth, production performance, immunity, and intestinal health of poultry. Besides providing nitrogen substrates and carbon framework for energy homeostasis and transamination, BCAA also function as signaling molecules in the regulation of glucose, lipid, and protein synthesis via protein kinase B and as a mechanistic target of the rapamycin (AKT-mTOR) signaling pathway that is important for muscle accretion. The level of leucine is generally high in cereals and an imbalance in the ratio among the 3 BCAA in a low protein diet would produce a negative effect on poultry growth performance. This occurs due to the structural similarity of the 3 BCAA, which leads to metabolic competition and interference with the enzymatic degradation pathway. Emerging evidence shows that the inclusion of BCAA is essential for the proper functioning of the innate and adaptive immune system and the maintenance of intestinal mucosal integrity. The recommended levels of BCAA for poultry are outlined by NRC (1994), but commercial broilers and laying hen breed standards also determine their own recommended levels. In this review, it has been noted that the requirement for BCAA is influenced by the diet type, breed, and age of the birds. Additionally, several studies focused on the effects of BCAA in low protein diets as a strategy to reduce nitrogen excretion. Notably, there is limited research on the inclusion ratio of BCAA in a supplemental form as compared to the ingredient-bound form which would affect the dynamics of utilization in different disease-challenged conditions, especially those affecting digesta passage ratio. In summary, this review encompasses the role of BCAA as functional AA and discusses their physiological effects on the productivity and health of poultry. The observations and interpretations of this review can guide future research to adjust the recommended levels of BCAA in feeding programs in the absence of subtherapeutic antibiotics in poultry.

Desempenho e rendimento de carcaça em frangos de corte de um a 46 dias alimentados com dietas contendo diferentes níveis de valina e reduzido teor proteico

Este estudo teve como objetivo avaliar as relações de valina:lisina digestíveis em dietas com teor reduzido de proteína bruta (PB) e os efeitos dessa redução sobre desempenho e rendimento de carcaça em frangos de corte. Foram utilizados 1200 pintos machos seguindo modelo inteiramente ao acaso, com seis tratamentos de seis repetições (exceto controle, com 10 repetições), compostos por 30 aves cada. O tratamento controle (T1) foi formulado conforme os níveis de proteína bruta e aminoácidos (AAs) recomendados por Rostagno et al . (2011), e os demais tratamentos (T2 a T6) tiveram seus níveis de PB reduzidos (4% em relação ao controle) e variaram em função da relação valina:lisina digestíveis, com cinco níveis equidistantes em intervalos de 0,07:1, variando de 0,63:1 e 0,91:1 (dietas até 21 dias) e de 0,64:1 e 0,92:1 (dietas após 21 dias). As seguintes características de desempenho foram avaliadas: ganho de peso, consumo de ração, conversão alimentar, viabilidade criatória e índice de eficiência produtiva. Aos 46 dias de idade, seis animais por repetição foram abatidos para determinação de rendimento de carcaça e de cortes comerciais. As diferentes relações valina:lisina digestíveis não influenciaram o desempenho dos animais (P>0,05) para nenhuma característica avaliada. A redução proteica piorou a conversão alimentar dos animais (P≤0,05) até os 21 dias. Os resultados sugerem que os níveis de valina utilizados não afetam o desempenho dos animais, apenas o rendimento de peito e que, portanto, a redução proteica não é recomendada durante as três primeiras semanas de criação.

Improving the Reliability of Optimal In-Feed Amino Acid Ratios Based on Individual Amino Acid Efficiency Data from N Balance Studies in Growing Chicken

Three consecutive nitrogen balance experiments with fast-growing male broiler chickens (ROSS 308), both during starter and grower periods, were conducted to determine the ideal ratios of several indispensable amino acids relative to lysine. The control diets based on corn, wheat, fishmeal, field peas, wheat gluten and soybean oil were formulated by computer optimizing to meet the assumed ideal amino acid ratios and to fulfill both the energy and nutrient requirements of growing chicken. According to principles of the diet dilution technique, balanced control diets were diluted by wheat starch and refilled by crystalline amino acids and remaining feed ingredients, except the amino acid under study. The lysine, threonine, tryptophan, arginine, isoleucine and valine diluted diets resulted in significantly lower protein quality as compared to control diet, especially following increased dietary lysine supply (experiments II and III) and stronger amino acid dilution (experiment III). Accordingly, the limiting position of individual amino acids was confirmed, and the derived amino acid efficiency data were utilized to derive ideal amino acid ratios for the starter period: Lys (100): Thr (60): Trp (19): Arg (105): Ile (55): Val (63); and the grower period: Lys (100): Thr (62): Trp (17): Arg (105): Ile (65): Val (79).

Determination of the fourth and fifth limiting amino acids in broilers fed on diets containing maize, soybean meal and poultry by-product meal from 28 to 42 d of age

1. Valine (Val) is considered the 4th limiting amino acid for broilers fed on diets containing ingredients from vegetable origin. However, Val and Isoleucine (Ile) may be co-limiting for broilers fed on diets containing animal protein meals. An experiment was conducted to examine growth responses and meat yield of broilers provided diets varying in digestible Val (dVal) and digestible Ile (dIle) concentrations from 28 to 42 d of age. 2. Eight experimental diets varying in dVal (dVal to dLys ratios from 0·66 to 0·76) and dIle (dIle to dLys ratios from 0·57 to 0·67) were studied; digestible Lysine (Lys) was formulated to 9·9 g/kg in all diets. 3. Broilers fed on a negative control (NC) diet supplemented with crystalline Val (L-Val) and crystalline Ile (L-Ile), dVal to dLys = 0·76 and dIle to dLys = 0·67, grew faster and had higher breast meat yield than birds fed on NC + L-Ile (dVal to dLys = 0·66 and dIle to dLys = 0·67), NC + L-Val (dVal to dLys = 0·76 and dIle to dLys = 0·57), and NC + reduced L-Val and L-Ile (dVal to dLys = 0·71 and dIle to dLys = 0·62). 4. Feeding broilers on the NC + L-Val and L-Ile (dVal to dLys = 0·76 and dIle to dLys = 0·67) diets gave similar BW gain, carcase weight and yield and total breast meat weight and yield to birds fed on the positive control-fed broilers with no added L-Val and L-Ile (dVal to dLys = 0·76 and dIle to dLys = 0·67). 5. These results indicate that Val and Ile are co-limiting in diets containing poultry by-product meal.

Dietary limitation of isoleucine and valine in diets based on maize, soybean meal, and meat and bone meal for broiler chickens

1. The dietary limitation of isoleucine (Ile) and valine (Val) was evaluated in broilers. Common diets were given to all broilers from 0 to 28 d of age. Experimental diets were provided from 28 to 42 d of age. 2. The experimental test diet was based primarily on maize, soybean meal, and meat and bone meal, and formulated to satisfy all nutrient recommendations with the exception of Ile and Val. 3. Diets were supplemented with L-Ile and L-Val at either 0·5 or 1·0 g kg⁻¹ of diet, alone or in combination. A diet composed only of commercially available amino acids and formulated to satisfy all nutrient requirements served as a positive control. 4. Body weight gain was depressed by the test diet, but recovered to a weight similar to birds fed on the positive control when Val was added to the test diet either alone or in combination with Ile. Feed efficiency improved when Val and Ile were simultaneously supplemented. 5. Abdominal fat yield was reduced with the combined supplementation of Val and Ile. Breast meat yield appeared to be more sensitive to Ile supplementation than to Val. 6. The results suggest that live performance may be more sensitive to Val, while breast meat yield was maximised with Ile supplementation. However, their combination is required for optimised growth and meat yield.

Valine requirements for immune and growth responses in broilers from 3 to 6 weeks of age

Four experiments were conducted to evaluate valine (Val) requirements in Ross 508 broilers from 3 to 6 weeks of age. Common diets were fed to broilers until 3 weeks of age. Growth and carcass measurements were taken in all experiments. Immune responsiveness measurements were taken in Experiments 1 and 2. Birds given 7.2 g Val/kg of diet in Experiment 1 had more abdominal fat than birds given 8.2 g Val/kg of diet, but there were no differences in growth or other carcass measurements. Because growth performance was not reduced in birds given 7.2 g Val/kg of diet, Val concentration was reduced to 6.4 g Val/kg of diet in Experiments 2 and 3. Increasing Val from 6.4 to 8.7 g Val/kg of diet resulted in linear increases for BW gain, feed efficiency and Val intake in male birds, and Val intake in female birds. Quadratic responses to increasing dietary Val were not observed in any experiment. There were no effects of Val on innate or adaptive immunity. A nonessential amino acid mixture containing the same nitrogen content as the L-Val additions in Experiment 4 was added and tends to support the idea that the responses to Val were specific and not due to increases in total nitrogen. Dose responses to Val resulted in male, but not female, birds given 7.3 g Val/kg of diet having improved BW gain and feed efficiency compared with birds receiving 6.4 g Val/kg of diet.