The Impact of Genotype and Age on Energy and Protein Utilization in Individually Housed Brown Laying Hens

Abstract

Responses to dietary energy and protein levels were compared between two egg-laying genotypes. Individually housed hens of a historic strain (HS) and a modern strain (MS) were compared. In Experiment 1 (Exp.1), four levels of true metabolizable energy, corrected for zero nitrogen retention (TMEn) and four levels of total lysine, were offered from 30 to 40 weeks of age. In Experiment 2 (Exp.2), three levels of apparent metabolizable energy, corrected for zero nitrogen retention (AMEn) and four levels of standardized ileal digestible lysine (SID Lys), were fed from 20 to 30 weeks of age. A randomized factorial block design (4 × 4 Exp.1 and 3 × 4 Exp.2) was applied. Energy utilization for egg output (EO) did not differ (NS), and both strains maintained a constant kJ intake (NS). The efficiency of SID Lys utilization for EO differed, with the MS being the more efficient (p < 0.034). A single model could be used to predict feed intake, using BW, EO, AMEn and SID Lys (r = 0.716). In conclusion, it is unlikely that the requirements of modern layer strains have increased. However, feeding programs should be adjusted for economic reasons and are dependent upon achievable feed intake under particular circumstances.

Heavy metal content in duck eggs and meat that consumes feed containing Sapu-sapu fish (Hypostomus plecostomus)

“…The results indicated that the Sapu-sapu fish is rich in minerals observed from the Sapu-sapu fish body, which has a hard layer of skin and a large head with hard bones. The mineral content found in this fish, especially Ca and P, is excellent to be used as a source of minerals to form egg shells and bones (Lukic et al 2009;Eleroğlu et al 2017;Kleyn et al 2021). The Ca and P mineral content in Sapusapu fish is relatively high at 4.26±0.0001% and 0.99±0.004%.…”