Soraya Rafiee; Ali Sadeghi-Sefidmazgi; Seyed Reza Miraei Ashtiani; Hasan Mehrabani Yeganeh
Abstract
Objective: Linear type traits are recorded for some reasons in dairy cattle. Cows might reach to a high length of productive life and milk yield based on their ideal scores of type traits. In the dairy industry, type traits have indirect economic values due to genetic correlation with production, reproduction, ...
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Objective: Linear type traits are recorded for some reasons in dairy cattle. Cows might reach to a high length of productive life and milk yield based on their ideal scores of type traits. In the dairy industry, type traits have indirect economic values due to genetic correlation with production, reproduction, clinical mastitis and length of productive life. The main object of our study was to identify type traits that have high enough genetic correlation with length of productive life, clinical mastitis and somatic cell score. Therefore, we conducted a meta-analysis as a statistical tool, on studies investigating the correlation between length of productive life, incidence of clinical mastitis, and somatic cell score with type traits in Holstein dairy cows.
Material and methods: A comprehensive search of the literature was conducted using the key words “genetic correlation”, “type traits”, “length of productive life”, “clinical mastitis”, “somatic cell score” , “Holstein cow” in Google Scholar search engine. Out of the 103 potentially relevant papers found, 75 studies were excluded from the analysis, because these studies did not contain appropriate data. Finally, from the search results, we prepared three real data sets in relation to genetic correlation of linear type traits with length of productive life (6 studies), clinical mastitis (8 studies), and somatic cell score (17 studies) in Holstein cows. These studies involved the total of 263065, 4716267 and 922090 animals, corresponded to length of productive life, clinical mastitis and somatic cell score, respectively. Analyses were performed using “metafor” procedure in R software package. Due to the differences in estimation methods and sample sizes in different studies, a random model was used to perform the meta-analysis and to estimate key statistics such as effect size, 95% confidence interval and measure of heterogeneity (.
Results and discussion: The obtained results from meta-analysis showed that the type traits with higher genetic correlations with length of productive life were central ligament 0.19 and udder depth 0.14. Furthermore, somatic cell score was more genetically correlated with body condition score (-0.31) and udder depth (-0.25). The largest genetic correlation of clinical mastitis estimated was with udder depth (-0.28) and teat length (-0.23). Test of heterogeneity (statistics) indicated that there was significant heterogeneity (variance among studies) at the highest level (more than 99%). Results of this study might indirectly be applicable for estimation of type traits’ economic values of Holstein cow’s selection indices.
Conclusion: Meta-analysis of genetic correlation between length of productive life, somatic cell score and clinical mastitis with linear type traits clarified that central ligament, udder depth, body condition score and chest width could be used as indicator traits in Holstein cows breeding programs. Results suggest that central ligament and udder depth as main mammary system traits potentially might be taking into account to constract indices for selection in dairy breeding programs. Cows can produce higher amount of milk and spend higher productive period when they have achieved to ideal scores of type traits.
Amin Kazemizadeh; Ahmad Zare Shahneh; Ali Reza Yousefi; Hasan Mehrabani Yeganeh; Zarbakht Ansari Pirsaraei
Abstract
The present study was conducted to investigate the effect of dietary Curcumin supplementation on histological parameters of testis in aged Ross 308 broiler breeder roosters. A total of twelve 48-week old broiler breeder roosters in a completely randomized design were randomly assigned to four treatments ...
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The present study was conducted to investigate the effect of dietary Curcumin supplementation on histological parameters of testis in aged Ross 308 broiler breeder roosters. A total of twelve 48-week old broiler breeder roosters in a completely randomized design were randomly assigned to four treatments and three replicates during a 13 weeks of experimental period. Treatments included no dietary Curcumin supplementation (control group), and daily supplementation of 10, 20, and 30 mg Curcumin/birds as mixed in the basal diet. At the end of the experimental period, all of the roosters were slaughtered, and testis tissue samples were collected. Testicular weight was higher in the roosters that daily received 30 mg Curcumin compared with the control group (P<0.05). Dietary supplementation of 20 and 30 mg Curcumin/day increased the diameter of seminiferous tubule compared to the control group (P<0.05). Seminiferous epithelium thickness was dose-dependently increased in Curcumin-supplemented birds compared to the control group (P<0.05). The number of spermatogonia cells was increased in all treatment groups compared to the control group (P<0.05). The number of Leydig cells was also increased in roosters received 20 and 20 mg Curcumin/day compared to the control birds (P<0.05). However, treatments did not affect the number of testis blood vessels (P>0.05). According to the results of the present study, dietary supplementation of 30 mg Curcumin/day/bird improves testis histological parameters in aged broiler breeder roosters.