Estimation of genetic parameters for semen traits in Egyptian buffalo bulls

Tropical Animal Health and Production (2023) 55:264 https://doi.org/10.1007/s11250-023-03680-7 REGULAR ARTICLES Estimation of genetic parameters for semen traits in Egyptian buffalo bulls Mohamed M. I. Salem1 · Amin M.S. Amin2 · Ayman F. Ashour2 · Ayman G. EL Nagar3 Received: 15 September 2022 / Accepted: 27 June 2023 / Published online: 10 July 2023 © The Author(s) 2023 Abstract This study was conducted to characterize semen traits (ejaculate volume (VOL), mass motility (MM), sperm livability (LS), percentage of abnormal sperms (AS), and sperm concentration (CONC)) of Egyptian buffalo bulls and evaluate the importance of some nongenetic factors (year (YC) and season (SC) of semen collection and age of bull genetically and environmentally at collection (ABC)) affecting the investigated traits. A total of 7761 normal semen ejaculates were collected from 26 bulls from 2009 to 2019. Single-trait and bivariate repeatability animal models using Bayesian methods were used to estimate variance components, heritability, repeatability, and genetic correlations among the investigated semen traits. YC and ABC exerted significant effects on most semen traits, whereas SC exerted no significant effect on all the investigated semen traits. Heritability estimates were 0.08, 0.52, 0.51, 0.04, and 0.49 for VOL, MM, LS, AS, and CONC, respectively. Repeatability estimates were 0.14, 0.82, 0.79, 0.06, and 0.78 for VOL, MM, LS, AS, and CONC, respectively. The genetic correlations between MM and each of LS and CONC were highly significant (0.99 ± 0.01 and 0.95 ± 0.14, respectively), and that between LS and CONC was also highly significant (0.92 ± 0.20). The high heritability estimates for MM, LS, and CONC combined with the favorable high significant genetic correlations between these traits indicated that direct selection for MM may be an effective method to enhance semen quality in Egyptian buffalo bulls and consequently improve fertility. Keywords Bayesian analysis · Egyptian buffalo · Genetic correlation · Heritability · Repeatability Introduction In dairy cattle, fertility is considered one of the most essential economic characteristics (Druet et al., 2009). In several countries, dairy cows’ fertility has been extensively examined in various cattle breeds for breeding purposes, whereas bull fertility has received limited attention (Weigel et al., 2006; Yin et al., 2019). Nevertheless, male fertility in cattle can be assessed either directly on the semen or indirectly via the females. The genetic makeup of bulls and environmental factors such as season (ambient temperature), age of bulls, * Mohamed M. I. Salem 1 Department of Animal and Fish Production, Faculty of Agriculture, University of Alexandria, Alexandria 21545, Egypt 2 Animal Production Research Institute, Agricultural Research Center, Dokki, Giza 12619, Egypt 3 Department of Animal Production, Faculty of Agriculture at Moshtohor, Benha University, Benha 13736, Egypt bull handlers, and the frequency of semen collection all influence semen traits (Stälhammar et al., 1989; Fuerst-Waltl et al., 2006). Moreover, a better understanding of these factors may enable the industry to improve artificial insemination (AI) in bull management to improve semen production (Mathevon et al., 1998). Furthermore, semen quality parameters are considered to be the most essential indications of bull fertility (Kumar et al., 2014; Singh et al., 2017), because low semen quality is a primary cause of female conception failure that has an impact on farm animals’ profitability as the use of bulls with unknown fertility in service, which reduces overall field fertility, is one of the key constraints to maximizing buffalo production (Oliveira et al., 2013). In dairy cattle and buffalo, AI is the most effective strategy for genetic improvement. AI aims to improve productive and reproductive traits by introducing daughters from superior breeding bulls into their herds (Mathevon et al., 1998; Kattab et al., 2022). Moreover, several studies have reported positive moderate-to-high genetic and phenotypic correlations between semen traits and nonreturn rate of dairy bulls (Morrell et al., 2018; Bhave et al., 2022; Gebreyesus et al., 13 Vol.:(0123456789) 264 Page 2 of 7 Tropical Animal Health and Production (2023) 55:264 2021). For instance, Berry and Kearney (2011) reported a positive (0.52) genetic correlation between male semen traits and female pregnancy rate, implying that selection for semen quality will lead to a parallel improvement in the female population’s pregnancy rate of dairy cows. In Egypt, the conception rate of buffalo cows is low and directly related to bulls’ semen quality. Hence, determining the genetic factors for semen traits could provide valuable information that can be used to increase conception rates in the Egyptian buffalo. In addition, the heritability and genetic correlations among different sperm quality traits can be used to predict how these traits will respond to genetic selection. Moderate to high heritabilities for semen traits in dairy bulls have been reported in several studies (Mathevon et al., 1998; Druet et al., 2009; Khattab et al. 2015; Berry et al., 2019; Khattab et al., 2022). Previous studies have also reported favorable genetic correlations between semen traits in dairy bulls, implying that an improvement in any trait will be accompanied by an improvement in the other traits as a correlated response due to selection (Berry et al., 2014; Olsen et al., 2020). However, there are limited studies on the genetic and environmental evaluation of semen traits in buffalo. Therefore, the objectives of the present study were to (1) evaluate the importance of some nongenetic factors (i.e., year and season of semen collection, age of the buffalo bull at semen collection) on semen traits (ejaculate volume, sperm mass motility, live sperm percentage, abnormal sperm percentage, and sperm concentration) and (2) estimate variance components, heritability, repeatability, and genetic and phenotypic correlations for the examined semen traits. The achievement of these objectives will allow for better understanding of the genetic basis of semen traits in the Egyptian buffalo, as well as contributing to their genetic improvement and evaluating the possibility of incorporating routine semen examination records into the genetic evaluation of fertility. were daily fed on a ration consisting of 4 kg concentrate feed mixture, 3 kg clover hay, and 4 kg rice straw. The average temperature, relative humidity, and THI in summer at Sakha, Kufr El-Sheikh Governorate, were 28.3, 65.8, and 78.2, respectively, while the corresponding values in winter were 16.1, 75, and 60.5, respectively. Each bull’s semen was collected twice a week at 8 AM through an artificial vagina (IMV, France), maintained at 42–45°C, and immediately transferred in a water bath (37°C) to the IMTC laboratory for further semen evaluation. The investigated semen trai (...truncated)