Effects of in ovo feeding with different ratios of D-L methionine to L- lysine on carcass parameters and blood metabolite concentrations in day-old Ross broiler chicks

Nowadays, in ovo injection is being used for increasing hatchability and growth, while reducing mortality rates and disease prevalence in poultry (Moran 2007). Methionine is the first limiting amino acid (Dilger and Baker 2007) and lysine is the second limiting amino acid in broilers (Tessseraud et al. 1996). Lysine has been used as a standard in ideal relationships of other amino acids (Baker 2009). Paradox results were observed using different ratios of methionine to lysine during the growth period in a way that some reported no effect (Lee et al. 1991; Si et al. 2004), while others reported positive effect on growth (Hickling et al. 1990; Mehri et al. 2012). Al-Murrani (1982) reported that the optimal methionine to lysine ratio for 7 d old chick embryo is 50.5%. Therefore, the aim of this study was to evaluate the effect of in ovo injection with different ratios of D-L methionine to L- lysine at 14th d of incubation on body weight parameters and blood metabolite concentrations in a day-old Ross 308 broiler chicks.
In this experiment, 210 fertile Ross 308 broiler breeder eggs were randomly assigned into 7 experimental groups with 30 individual eggs per each group. Experimental treatments including control (non-injected), sham-control (injected sterile water), and 40.5, 45.5, 50.5, 55.5 and 60.5 D-L methionine to L-lysine ratios were injected into the amniotic fluid at 14 d of incubation through the broad end of eggs. On day 22 (one day post hatch), 4 chickens per replicate were selected, bled, and then slaughtered to measure internal organ weights.
Hatchability rate was not affected by treatments (P>0.05), though the highest hatchability was observed in 45.5% D-L methionine to L-lysine ratio (Fig 1). In other studies, no effect (Mottaghitalab and Shafiymanesh 2015) or reducing effect (Coşkun et al. 2014) of in ovo injection with D-L methionine was observed. All the treatment groups showed higher chick weight in comparison with control groups (P0.05), while reduced sera triglyceride (P The overall results of the present experiment indicated that in ovo injection of different ratios of D-L methionine to L- lysine up to 55.5% ratio had an increasing effect on carcass efficiency, muscle production, and protein, while a decreasing effect on triglyceride and urea concentration in a day old Ross broiler chicks.