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

There are limited investigations on the role of feed additives in easing transition of pullets to egg production phase. We investigated the effects of supplementation of bacitracin methylene disalicylate (BMD) and select feed additives (myristic acid [MA], benzoic acid [BA], and Aspergillus niger probiotic [PRO]) in feeding program for pullets from the 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 five 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 and 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 Escherichia coli than birds fed BMD, BA, and PRO diets. Consequently, BMD, BA, and PRO birds had a higher (P = 0.011) Lactobacilli: E. coli ratio (LER) than hens fed the basal diet. Specifically, relative to basal-fed hens, the LER of the BMD, MA, BA, and PRO hens was higher by 37%, 21%, 26%, and 45%, respectively. Moreover, birds fed PRO tended to have a higher concentration of ceca digesta acetic acid (P = 0.072) and a lower concentration of isobutyric acid (P = 0.096). In conclusion, supplementing pullet diets with broad-spectrum antibiotics or feed additives (MA, BA, and PRO) had a positive impact on FI, and egg production linked to modulation of indices of gut health. The results suggested supplementing feed additives in feeding programs for pullets at the onset of lay can bolster productivity outcomes. The transition from rearing to production is a very stressful period for the pullet with implications on lifetime egg production and livability. The pullet is not only adapting to her new environment, but she must support body weight development amid looming peak egg production. In recognition of the critical role of pullet condition at onset lay and the subsequent impact on flock performance, significant research has been completed on management and feeding programs for pullets. One area that has received little attention is the role of modulating gastrointestinal ecology through the supplementation of feed additives at the onset of lay. The objective of the present study was to evaluate the effects of supplementing selected feed additives including myristic acid (MA), benzoic acid (BA), and Aspergillus niger (PRO) in a feeding program for pullets from the onset of lay through to 31 weeks of age (woa). Bacitracin, often added in diets for laying hens at subtherapeutic levels to manage stress and intestinal microbiota, was tested for comparison. The results indicated that MA, BA, and PRO had a commensurate impact to bacitracin on feed intake and egg production.