Comparative impact of bacitracin and select feed additives in the feeding program of Lohmann LSL Lite pullets at the onset of lay through to 31 weeks of age

Abstract

Abstract There are limited investigations on the role of feed additives in easing transition of pullets to egg production phase. We investigated effects of supplementation of bacitracin methylene disalicylate (BMD) and select feed additives (myristic acid (MA), benzoic acid (BA), and Aspergillus Niger (PRO)) in feeding program for pullets from onset of lay through to 31 weeks of age (woa). Parameters measured included hen-day egg production (HDEP), feed intake (FI), feed conversion ratio (FCR), egg quality characteristics, ceca microbial activity, apparent retention of components, and plasma metabolites. A total of 1,200 Lohmann LSL Lite pullets were procured at 18 woa and placed in enriched cages (30 birds/cage) based on body weight (BW) and allocated to 5 diets. The diets were: a basal diet formulated to meet specifications or basal mixed with either BMD, MA, BA or PRO. Birds had free access to feed and water throughout the experiment. Between 18 to 20 woa, birds fed BMD ate a similar (P>0.05) amount of feed to BA birds, but more (P=0.0003) than birds fed basal, MA or PRO diets. Basal birds had lower HDEP (P=0.001), and lighter eggs (P<0.0001) than birds fed any of the feed additives between 21 and 31 woa. The basal hens had a higher (P=0.009) abundance of E. coli than birds fed BMD, BA, and PRO diets. Consequently, BMD, BA, and PRO birds had a higher (P=0.011) Lactobacillus: E. coli ratio (LER) than hens fed the basal diet. Specifically, relative to basal-fed hens, the LER ratio of the BMD, MA, BA, and PRO hens was higher by 37, 21, 26, and 45%, respectively. Moreover, birds fed PRO tended to have higher concentration of ceca digesta acetic acid (P=0.072) and lower concentration of isobutyric acid (P=0.096). In conclusion, supplementing pullet diets with broad spectrum antibiotic or feed additives (MA, BA, and PRO) had positive impact on feed intake, and egg production linked to modulation of indices of gut health. The results suggested feed additives in feeding programs for pullets at the onset of lay can bolster productivity outcomes.