Laying performance, genetic parameters, and the expression of FSHß, LHß, FSHR, and LHR genes in Japanese quails selected for early egg production.

Investigating the impact of early egg production selection (the first 90 d of laying) on egg production features, cumulative selection response (CSR), and the mRNA expression of gonadotropins (FSHß and LHß), and their receptors (FSHR and LHR), in Japanese quails was the goal. The selection experiment involved 1293 females in all, 257 from the base group and 1036 from the 4 selected generations. Age and body weight at sexual maturity (ASM, BWSM), weight of the first egg (WFE), days to the first 10 eggs (DF10E), egg mass for the first 10 eggs (EMF10E), egg weight (EW), egg number at the first 90 d of laying (EN90D), and egg mass at the first 90 d of laying (EM90D) were all recorded. Most egg production traits had heritability estimates that were low to moderate and ranged from 0.17 to 0.33., where the highest estimates were reported for EN90D (0.33) and BWSM (0.32). With the exception of EN90D, low to moderate positive genetic correlations were observed between ASM and other egg production traits (0.17-0.44). The fourth generation showed significantly (P < 0.05) lower ASM and DF10E but higher BWSM, WFE, EN90D, EM10E, and EM90D when compared with the base generation. CSR were significant (P < 0.05) for ASM (-6.67 d), BWSM (27.13 g), WFE (0.93 g), DF10E (-1.25 d), EN90D (7.24 egg), EM10E (10.57 g), and EM90D (140.0 g). FSHß, LHß, FSHR, and LHR gene mRNA expression was considerably (P < 0.05) greater in the fourth generation compared to the base generation. In conclusion, selection programs depending on the efficiency of egg production (EN90D) could improve the genetic gain of egg production traits and upregulate the mRNA expression of FSHß, LHß, FSHR, and LHR genes in selected quails (fourth generation). These findings might help to enhance breeding plans and create commercial lines of high egg production Japanese quails.

Allele mining in prolactin receptor gene and its association with some economic traits in Egyptian goat breeds.

The objectives of the current study were to identify polymorphism in the prolactin receptor (PRLR) gene among three Egyptian goat breeds (Zaraibi, Damascus, and Barki) and to investigate the association between PRLR genotype, parity, season of kidding, and litter size factors with milk yield and reproductive traits of Zaraibi goats. One hundred and ninety blood samples were collected for DNA extraction, with 110 from Zaraibi, 40 from Barki, and 40 from Damascus breeds. Three genotypes, CC, CT and TT, for the prolactin receptor gene were identified in the 190 DNA samples using restriction fragment length polymorphism and were confirmed by direct sequencing technique. Milk yield during suckling and lactation periods in addition to age at first conception, gestation length, and litter size were determined in 110 Zaraibi goats. The Zaraibi goats recorded the highest heterozygosity (0.495) and the effective number of alleles (1.972). The g.62130C > T SNP showed a significant association (p < 0.01) with suckling, lactation, and total milk yield of Zaraibi goats with the highest values recorded at the third parity. Age at the first conception and gestation length traits were significantly influenced by the kidding season (p < 0.05) with younger age in autumn and shorter length in spring seasons. Milk yield during the suckling period was significantly (p < 0.01) higher in the case of triplets' litter size. The current study showed that litter size and parity played an important role in the amount of Zaraibi goats' milk yield. The g.62130C > T SNP of the PRLR gene may be a useful marker for assisted selection programs to improve goat milk yield during suckling and lactation periods with the heterozygous genotype CT recording the highest values.

Genetic analysis of prolificacy, milk production and composition traits in Egyptian Zaraibi goats.

This study was conducted to genetically and environmentally characterize prolificacy (litter size and weight at birth; LSB and LWB and litter size and weight at weaning; LSW and LWW, respectively), milk yield at the 7th (MY7), 15th (MY15), 30th (MY30), 60th (MY60), 90th (MY90) day of lactation and monthly milk yield (MMY) and milk composition traits in Egyptian Zaraibi goats. A total of 443 and 421 records produced by 121 Zaraibi lactating goats were used to assess prolificacy and milk production traits, respectively. The milk composition traits were measured using 371 milk samples obtained at random from 53 goats. The fourth parity showed the highest values for LWB, LWW, and MMY (3.62, 18.15, and 28.99 kg, respectively). Milk composition traits revealed an inverse tendency, decreasing until the second month and then increasing until the seventh month. The heritability estimates ranged from 0.07 to 0.13, from 0.04 to 0.39, and from 0.07 to 0.33 for prolificacy, milk yield, and milk composition traits, respectively. Negatively high genetic correlations between MMY and all milk composition traits were found. MMY had the highest estimate of heritability (0.39 ± 0.07), this means that the genetic improvement of this trait could be achieved through direct selection.

Genetic and Phenotypic Characterization of Domestic Geese (Anser anser) in Egypt.

The objectives of this study were to achieve phenotypic characterization of three domestic Egyptian goose populations collected from three different geographical zones (Kafr El-Sheikh, Fayoum and Luxor) and to perform genetic characterization of these three populations based on mtDNA D-loop and 12 microsatellite markers. The body measurements of 402 domestic mature geese belonging to these three governorates showed that the lengths of the head, culmen and tarsus and the live body weight varied significantly among the three studied Egyptian goose populations. After alignment of a 710-base-pair segment of the goose mtDNA control region, there was a single haplotype in the three Egyptian goose populations, indicating the same maternal origins. The genotyping of the 12 microsatellite markers showed low diversity indices, including average observed (NA) and effective (NE) number of alleles and observed (HO) and expected heterozygosity (HE) (3.333, 1.760, 0.277 and 0.352, respectively), and a high inbreeding coefficient (FIS = 0.203) across the three Egyptian goose populations. The high inbreeding and low genetic and morphological differentiation of Egyptian geese could be corrected by establishing a large base population through capturing small populations with the highest genetic variation. The findings of the current study can therefore serve as an initial guide to design further investigations for developing conservation programs of Egyptian geese genetic resources.

Association of ß-casein gene polymorphism with milk composition traits of Egyptian Maghrebi camels (Camelus dromedarius).

The objectives of this study were to detect the polymorphism of 2126 A / G SNP in the ß -casein (CSN2) gene among Egyptian Maghrebi camels and to investigate the association of 2126 A / G SNP genotypes, parity, lactation stage, and temperature-humidity index (THI) with the milk composition traits of Maghrebi camels. Sixty-eight hair samples were collected from three different populations of Maghrebi camels for DNA extraction. Fat, protein, total solids, solids-not-fat, and lactose percentages were determined in Maghrebi camel milk using an automatic milk analyzer device. Three different genotypes - A/A, A/G, and G/G - were identified in the 5 ' flanking region of ß -casein gene by using PCR-RFLP method with the A/G genotype showing the highest frequency. Association among these three genotypes with milk composition traits suggests a positive effect of A/A genotype on acidity and protein percentage. Higher protein and acidity values were observed in the milk of individuals carrying the A/A genotype. The protein percentage of this study significantly increased from the first till the fourth parity and then decreased. Fat and total solid percentages were significantly higher in the late stage of lactation, while lactose showed a decreasing trend from the early till the late stages of lactation. Fat and protein percentages were highest in the low THI class. Our results encourage the utilization of Maghrebi camel milk for cheese and butter processing at the late lactation stages of the middle parities of their productive life. Moreover, the A/G SNP of the CSN2 gene may be used as a DNA marker in selection programs for the improvement of camel milk composition. Further studies are needed in order to fully explore the variation in the chemical composition of camel milk due to the effect of CSN2 gene, parity, lactation stage, and THI factors.

Polymorphism of lactoferrin gene in Egyptian goats and its association with milk composition traits in Zaraibi breed.

The objectives of this study were to identify polymorphisms in the lactoferrin gene among three Egyptian goat breeds (Barki, Zaraibi, and Damascus) and to investigate the effect of LF genotype, parity, and lactation stage on milk composition traits of Zaraibi goats. One hundred and thirty-two blood samples were collected for DNA extraction, with 53 from Zaraibi, 40 from Damascus, and 39 from Barki breeds. Fat, protein, total solids, solids-not-fat, and lactose percentages were determined in Zaraibi goat milk using an automatic milk analyzer. Two genotypes, GG and GA, in the lactoferrin gene were identified using single-strand conformation polymorphism and were confirmed by direct sequencing technique. The Zaraibi breed recorded the highest heterozygosity (0.272) and effective number of alleles (1.369), while the Damascus breed recorded the lowest values. The G/A SNP showed a significant association with protein, solids-not-fat, and total solid content of Zaraibi goat milk. Protein, solids-not-fat, and total solid content in our study were significantly higher at early and late parities. Lactose percentage decreased significantly from early to late parity. Fat, protein, solids-not-fat, and total solid content were significantly higher at early and late stages of lactation, and our results encourage the utilization of Zaraibi goat milk in cheese and butter processing at these stages. Moreover, the G/A SNP of the LF gene may be a useful marker for assisted selection programs to improve goat milk composition.