In ovo injection of branched-chain amino acids: Embryonic development, hatchability and hatching quality of turkey poults

Physiological effects of in ovo delivery of bioactive substances in broiler chickens

The poultry industry has improved genetics, nutrition, and management practices, resulting in fast-growing chickens; however, disturbances during embryonic development may affect the entire production cycle and cause irreversible losses to broiler chicken producers. The most crucial time in the chicks' development appears to be the perinatal period, which encompasses the last few days of pre-hatch and the first few days of post-hatch. During this critical period, intestinal development occurs rapidly, and the chicks undergo a metabolic and physiological shift from the utilization of egg nutrients to exogenous feed. However, the nutrient reserve of the egg yolk may not be enough to sustain the late stage of embryonic development and provide energy for the hatching process. In addition, modern hatchery practices cause a delay in access to feed immediately post-hatch, and this can potentially affect the intestinal microbiome, health, development, and growth of the chickens. Development of the in ovo technology allowing for the delivery of bioactive substances into chicken embryos during their development represents a way to accommodate the perinatal period, late embryo development, and post-hatch growth. Many bioactive substances have been delivered through the in ovo technology, including carbohydrates, amino acids, hormones, prebiotics, probiotics and synbiotics, antibodies, immunostimulants, minerals, and microorganisms with a variety of physiological effects. In this review, we focused on the physiological effects of the in ovo delivery of these substances, including their effects on embryo development, gastrointestinal tract function and health, nutrient digestion, immune system development and function, bone development, overall growth performance, muscle development and meat quality, gastrointestinal tract microbiota development, heat stress response, pathogens exclusion, and birds metabolism, as well as transcriptome and proteome. We believe that this method is widely underestimated and underused by the poultry industry.

L-Leucine In Ovo Administration Causes Growth Retardation and Modifies Specific Amino Acid Metabolism in Broiler Embryos

L-Leucine (L-Leu) in ovo administration was demonstrated to afford thermotolerance and modified amino acids metabolism in post-hatched broiler chicks under heat stress. This study aimed to investigate the changes in embryonic growth and amino acid metabolism after in ovo injection of L-Leu. Fertilized broiler eggs were subjected to in ovo injection of sterile water or L-Leu on embryonic day (ED) 7. The weight of embryos and yolk sacs were measured on ED 12, 14, 16, and 18. Plasma and livers were collected on ED 14 and 18 for free amino acid analysis. The weight and relative weight of embryos were significantly lowered by in ovo administration of L-Leu, but those of yolk sacs were not altered. Moreover, L-Leu in ovo injection significantly reduced the plasma proline concentration during embryogenesis and increased the plasma concentrations of tyrosine (Tyr) and lysine (Lys) in ED 18. Hepatic Lys concentration was also significantly increased by L-Leu in ovo injection. Interestingly, Leu concentrations in the plasma and liver were not affected by L-Leu administration. These results indicated that in ovo administered L-Leu was metabolized before ED 14 and affected embryonic growth and amino acid metabolism during embryogenesis.

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

Objective

The objectives of this study were to compare the effects of normal and low protein content (PC) of starter diet supplemented or not with blends of branched-chain amino acids (BCAAs) on growth performance of broilers under summer conditions and to investigate whether these effects altered some quality traits and the characteristics of gastrointestinal tract.

Methods

A total of 768 mixed-sex broiler chicks (Ross 308, one-d-old) with an average initial body weight (BW) of 47.6±1.03 g were allocated into six treatments with four replications in 2×3 factorial arrangement. Factors were: PC, normal (N, 22% to d 15); and low (L, 20% to d 15); and added BCAA blends, L-leucine, L-isoleucine, and L-valine at zero (0L:0I:0V); 1.0, 0.25, and 0.25 (4L:1I:1V); or 1.0, 0.25, 0.75 (4L:1I:3V) g/kg of diet. Hence, six dietary treatments were named as N0L:0I:0V, N4L:1I:1V, N4L:1I:3V, L0L:0I:0V, L4L:1I:1V, and L4L:1I:3V. Average indoor temperature and humidity were 32.8°C±1.7°C and 61.1% ±4.12%, respectively.

Results

BW, feed conversion ratio (FCR) and carcass weight were not affected by PC, BCCA and their interaction (p>0.05). The L diets decreased the water holding capacity of the breast (p = 0.002) and thigh (p = 0.050) meats and dressing percentage (p = 0.005) compared to the N diets. The 4L:1I:1V diet decreased breast yield compared to the 0L:0I:0V diets (p = 0.041). The effect of PC on feed intake, mortality and gastrointestinal trait weight were depended on the L:I:V ratios under summer conditions due to interactions between factors (p<0.05). The FI and mortality of L4L:1I:1V broilers were lower than those of N4L:1I:1V birds (p<0.05).

Conclusion

It was concluded that the blends of BCAAs used failed to improve performance and to promote breast yields, because diets with normal or with reduced protein supplemented or not with BCAAs up to d 15 produced a similar BW and FCR in broilers raised in hot-climate conditions.