Influence of Genotype on Productivity and Egg Quality of Three Hen Strains Included in a Biodiversity Program

Abstract

The aim of the study was to evaluate the effect of genotype on the productivity and egg quality of three hen strains included in the genetic resource protection program in Poland. The study encompassed populations of laying hens, i.e., Rhode Island Red/RIR (R-11 and K-22) and Rhode Island White (A-33). The analysis over five generations included the basic production traits, i.e., the weight of the birds at 20 weeks (g), egg weights at 33 and 53 weeks, sexual maturity, the number of eggs laid up to 56 weeks of age, and hatchability parameters. In addition, the effective population size (Ne) and flock homozygosity coefficient (Fx) were calculated for each breed. Population health during the rearing and production periods was also recorded. The study also determined egg content and shell quality traits in relation to the age of the hens. The birds were kept on litter at a stocking rate of 5 hens/m2 and fed ad libitum with a standard feed mixture for hens. Based on the results, it was concluded that the evaluated hen populations (R-11, K-22, and A-33) are valuable strains, representing a reservoir of unique phenotypic and egg quality traits. It was shown that the random mating system used in the reproduction of flocks effectively protects the populations from an increase in the degree of inbreeding. An influence of hens’ origin (genotype) and age on the performance results, as well as egg quality traits, was found. Over five generations, the evaluated hen strains were characterized by high survival rates (above 98%). The study also found a large variation between the R-11 and K-22 strains and the A-33 strain in terms of the evaluated performance traits, especially in the body and egg weights, sexual maturity age, and laying performance of hens. The earliest to start laying were hens from the K-22 strains, which also showed significantly (p ≤ 0.05) higher laying performances compared to R-11 hens. The results also indicate that the quality of eggs from hens of the compared strains varied. This was particularly true for such traits as shell color; egg, shell, and yolk weight; and shell quality. It was also shown that many egg and shell quality traits change with the age of the hens. The analysis of the obtained data indicates that the adopted methods of conservative breeding for these populations have influenced the success of the conservation program.

The quality of eggs derived from Polbar and Greenleg partridge hens - Polish conservative breeds

“…Similar results were also reported by other authors [Sokołowicz et al 2018, Fathi et al 2021 while in some works this trait in eggs of the commercial strains is reported at 25-26% [Wu et al 2007] or 25-27% [Wengerska et al 2023]. The Rhode Island Red and Rhode Island White breeds, used globally for laying production, have a yolk percentage as 26.5% of egg weight at the 33rd week of life [Calik and Obrzut 2023]. In unselected local Italian hen breeds, the yolk percentage per egg was 31.1% compared to 24.9% in commercial highproducing hybrids [Sirri et al 2018].…”

“…The parameters characterising shell quality of both breeds eggs were at a satisfactory level. Shell thickness decreases with birds' age [Sokołowicz et al 2018, Sokołowicz et al 2019, also a decrease in shell strength with age [Rodriguez-Navarro et al 2002, Sokołowicz et al 2019, Calik and Obrzut 2023 was confirmed. In the case of Polbar, a slight (but insignificant) decrease in shell thickness with age, but it was also observed that shell density and strength increased with age in this breed.…”

“…At the moment, there are three breeding laying hen farms in Poland with 12 hen strains (6 breeds), while the "Programme for the conservation of genetic resources of laying hen populations" covers 8 poultry breeds with 13 strains [Calik and Obrzut 2023], most of which have been included by the FAO in the world genetic resources to be conserved. Most poultry breeding populations are based on breeds brought to Poland several decades ago.…”

Enriching Eggs with Bioactive Compounds through the Inclusion of Grape Pomace in Laying Hens Diet: Effect on Internal and External Egg Quality Parameters

“…They reported that high quantities of caffeine could eventually bring about shell fractures caused by calcium loss and availability. Finally, as commonly observed in laying hen husbandry [29], eggshells were thinner for light hens than for semi-heavy ones (370 vs. 386 µm, p = 0.038). In this sense, Silversides and Scott [44] found that the shell percentage in the egg was lower for ISA white hens than for ISA brown hens.…”

“…The genetics of laying hens and the diet consumed are the main sources of variation affecting egg production and quality [28,29]. Conventionally, two types of laying hens are used worldwide in laying hen husbandry: light hens (hens laying white eggs) and semi-heavy hens (hens laying brown eggs).…”