Effects of lifetime feeding of hydrolyzed yeast to broiler breeders on egg production, quality, and hatchling attributes

The effects of lifetime feeding of hydrolyzed yeast (HY) to broiler breeders (BB) on egg production, egg quality, and hatchling attributes were investigated. The birds were selected from two groups reared on diets with or without 0.05 % HY from hatch. The birds were placed for the current study at 22 weeks of age (woa) in 16-floor pens (20 female and 2 male/pen) based on rearing diet identity. Isocaloric and isonitrogenous diets were formulated without or with 0.05 % HY for three production phases: 1 (22 to 40 woa), 2 (41 to 50 woa), and 3 (51 to 64 woa) and allocated within rearing diet identity in a completely randomized block design (n = 8). The birds had free access to water, whereas feed allocation was per breeder guidelines. Egg count/ pen was recorded four times daily from 25 woa (the time point the first egg was laid) to calculate hen day egg production (HDEP), and cumulative eggs per hen housed (CEPHH). From 28 woa, eggs were selected randomly for eggshell breaking strength (ESBS) and eggshell thickness (EST) and for incubation to determine fertility, hatchability, in-ovo mortality, chick sex ratio, and chick weight. Two hens per pen were necropsied at 44 and 64 woa for breast, abdominal fat and liver weights. There were no (P>0.05) interactions between diet and BB age or the diet effects on response criteria. Broiler breeder age effect (P<0.05) was such that HDEP, ESBS, EST, hatchability declined whereas egg weight, in-ovo mortality, and chick to egg weight ratio increased with age. Control birds had more (P=0.015) CEPHH (25 to 64 woa) than HY40 birds. In conclusion, the more CEPHH for the control group was reflective of hen mortality whereases the broiler breeder age effects were as expected. Overall, lifetime feeding HY to broiler breeders from hatch had no impact on egg production rate, egg quality and hatchling attributes.