The effects of dietary factors on the development and viability of avian embryos have been extensively documented. A good nutritional status of the parent birds is crucial to the transfer to the egg of an adequate, balanced supply of nutrients required for normal development of the embryo. The consequences to the embryo may be lethal if the egg contains either inadequate, excessive, or imbalanced levels of nutrients. As nutritional deficiencies or excesses occur, it is common for the effects on the embryo to also become more severe and to occur at earlier stages of development. The type of nutritional stress signs visible in the embryo often depend upon the severity of the maternal nutritional stress. Diseases, parasitic infections, toxins, poisons, or drugs may also cause nutritional or pseudonutritional problems with hatchability.
Two experiments were conducted to evaluate effects of strain [five in Experiment (Exp.) 1 and six in Exp. 2)] and age (29, 47, and 57 wk in Exp. 1 and 29, 41, and 52 wk in Exp. 2) of commercial broiler breeders on incubation time and chick weight. Highly significant differences in egg weight were found among strains in both Exp. After adjusting for effects of egg weight, significant effects of strain, age, and their interactions were found on incubation time, egg weight at transfer, and chick weight at hatch in Exp. 1, but not in Exp. 2. Mean incubation times varied among strains from 496.6 to 498.8 h in Exp. 1 and from 499.3 to 501.9 h in the second experiment. In Exp. 1, incubation time decreased from 498.6 h when breeders were 29 wk to 494.8 at 47 wk, whereas in Exp. 2, it decreased from 510.5 h at 29 wk to 495.1 h at 41 wk. This decrease also resulted in a negative correlation between egg weight and incubation time. Differences due to strain and age were found for yolk and albumen percentage and yolk: albumen ratio. Percentage yolk was 27.2 and 32.7% and percentage albumen was 60.1 and 55.9% in eggs from 29 to 52 wk breeders, respectively. Shell percentage was significantly affected by strain. Strain by age interactions were found for each response in Exp. 1 but only for set and chick weight in Exp. 2. Differences among incubators were found only for incubation time; interactions of incubation time and strain and age were also detected. Results indicate that genotype, age of the female breeder, and incubator should be considered along with their interactions to obtain optimum hatching performance.
Semen Quality Characteristics and FertilityThe selection of males for breeder flocks is usually based on such characteristics as posture, body conformation, maturity, body size, ~~~~ ~ ~ ~ *Ha. Agr. Exp. Sta. Journal Series No. 1062. 95 96condition of the legs and feet, appearance of the head, general health and vigour, and appearance of eyes. Although these characteristics are useful in selecting males they do not assure that high fertility will be obtained. Several attempts have been made to relate various semen quality characteristics to fertility. There is much disagreement in the literature, however, regarding the importance and reliability of semen traits in predicting fertility. Differences can, of course, be expected between the results obtained from natural mating and artificial insemination. Although measurements of semen traits have been succcssful in detecting sterile birds, the prediction of fertilizing capacity appears to be complex and influenced by numerous factors other semen quality.In order to make fertility predictions or male breeding worth predictions based on semen evaluation, high correlations between semen characteristics and fertility must be found. Then a statistical model may be fitted using the semen quality values as independent variables to define the dependent variable, fertility. In addition, when attempting to obtain an estimate of fertility or breeding potential, one must keep in mind that it is influenced by genetical, physiological and social factors.Semen quality characteristics are generally believed to be inherited (Lake, 1971; Marini and Goodman, 1969) and differences in semen characteristics and fertility have been reported between breeds (Parker et al., 1942;Allen and Champion, 1955; Taneja and Gowe, 1961 a and b;McDaniel and Craig, 1962), between inbred lines (Williams and McGibbon, 1956; De-Silva, 1963) and between families (Boone, 1968).Heritability values for such traits as semen quantity, concentration and motility were found to be high (Soller et al. 1965b) as were the repeatabilities of such measurements. Nestor and Brown (1976a) reported that measurements of semen quality made early in the reproductive life of the male were not closely correlated with subsequent evaluations and did not permit accurate prediction of future semen production. Nestor (1976) successfully selected turkeys for increased semen yield, however, there were no consistent changes in percent fertility, percent hatchability of fertile eggs or number of poults per hen associated with the increases in semen yield. Some success also has been reported for the selection for fertility when using frozen chicken semen (Scott et al., 1977).Concentration of spermatozoa in semen has been claimed to be significantly related to fertility (following AI), having a correlation coefficient of 321 (Kamar, 1960) and .481 (Boone, 1968). Others have presented data indicating that it is not significantly related to fertility (
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.