Commercially available amino acid supplementation of low-protein diets for broiler chickens with different ratios of digestible glycine+serine:lysine

Abstract

This work studied the effect of supplementing commercially available amino acids in low-protein diets using different ratios of digestible (dig) glycine+serine:lysine (Gly+Ser:Lys) on performance, serum parameters, feathering, and litter characteristics of broiler chickens during the starter period. A total of one thousand fifty 1-d-old Cobb-Vantress male chicks were distributed in a completely randomized experimental design into 6 treatments with 5 replicates of 35 birds each. The treatments were as follows: T1, control diet based on corn and soybean meal formulated with 22% CP (dig Gly+Ser:Lys ratio of 147); T2, diet with a 2% CP reduction, supplemented with Val (dig Gly+Ser:Lys ratio of 137); T3, similar to T2 with the addition of Gly (dig Gly+Ser:Lys ratio of 147); T4, diet with a 3% CP reduction, supplemented with Val, Ile, and Arg (dig Gly+Ser:Lys ratio of 127); and T5 and T6, similar to T4 with the addition of Gly (dig Gly+Ser:Lys ratios of 137 and 147, respectively). At 7 and 21 d, broilers that had received diets with a 3% CP reduction (19% CP) and a Gly+Ser:Lys ratio that was equivalent to 127 had lower G:F (P < 0.05) and lower total protein and albumin serum concentrations (P < 0.05) than those broilers that received the control feed. However, these parameters were restored to the same level as the control diet with an increase in the dig Gly+Ser:Lys ratio from 127 to 137 and 147. Diets with a 3% CP reduction (19% CP) resulted in litter with reduced (P < 0.05) nitrogen content and lower ammonia emission than the litter of broilers receiving the control diet. The treatments did not influence (P > 0.05) the feather length or feathering scores at 21 or 28 d of age. The supplementation of essential amino acids while maintaining dig Gly+Ser:Lys ratios at and above 137 allowed for a reduction in the dietary CP of 3% without undermining the performance, feathering or serum parameters of early stage broilers.

Glycine plus serine requirement of broilers fed low-protein diets : a dose response study

“…All low-protein treatments numerically had a higher dry matter litter content than the control, but only 12.4 GLY,14.9 GLY,15.7 GLY and 12.4 GLY+THR diet programs differed significantly from the control. These results were in line with the findings of Kamran et al (2010) and Ferguson et al (1998a), but not completely in line with Moran et al (1992), Elwinger andSvensson (1996), Ferguson et al (1998b), Khajali and Moghaddam (2006) and Ospina-Rojas et al (2012), who noted also a lower total nitrogen content but no change in the moisture content of the litter because of supplementing low-protein diets.…”

“…In general, lower dietary crude protein levels seem to reduce the N content of the litter (Elwinger and Svensson, 1996;Fergusson et al, 1998a,b;Khajali andMoghaddam, 2006 andOspina-Rojas et al, 2012), and our results confirmed that as well. Ferguson et al (1998a) reported that a 2% reduction in dietary crude protein decreased litter ammonium-N and nitrogen concentration by 31 and 16%, respectively.…”

“…According to Ospina-Rojas et al (2013) it is known that the enzymes Thr aldolase and Thr dehydrogenase catabolize excess Thr into Gly, thereby conserving the energy used in the synthesis of endogenous Gly (9 ATP/mol) and, thus, increasing the amount of energy available for optimal growth. As mentioned earlier, some studies showed that Gly (+ Ser) in low-protein diets were limiting performance at young age (Corzo et al, 2004;Dean et al, 2006;Ospina-Rojas et al, 2012). This was, however, not confirmed in a study of Siegert et al (2015a).…”

“…In this experiment the total nitrogen content and ammonium-N content of the litter of broilers fed the low-protein diets was 16% and 20% lower than the control group. Ospina-Rojas et al (2012) found that birds fed diets with a CP reduction of 3% had 24% less N excretion via the litter and 37% ammonia emission, compared to birds fed a control diet.…”

“…Therefore, it is hypothesised that marginal levels of dietary Gly+Ser are the reason for the decrease in performance of broilers when dietary CP is decreased by more than 3%. Glycine supplementation was shown to completely recover bird's performance during the starter phase when these birds were fed a low-protein diet (Corzo et al, 2004;Dean et al, 2006;Ospina-Rojas et al, 2012). Van Harn et al (2017) showed that dietary protein levels in the grower and finisher diets can be reduced up to 3% without deterioration of animal performance, provided that the supply of essential amino acids (including Gly), and their ratios relatively to lysine (Lys), are maintained on the level of the control diet.…”