Animal Genetics and Breeding

The production records on 228 Gir cows with 680 lactations sired by 52 bulls, maintained at Cattle Breeding Farm, Junagadh Agricultural University, Junagadh, for 24 years (1987 – 2010) were studied. The data were analyzed to study the effect of period of calving and season of calving as fixed effect on the reproduction trait viz., age at first calving. The average age at first calving in Gir cows was found to be 1490.50 ± 111.04 days. The analysis of variance revealed highly significant effect of period of calving on age at first calving indicating thereby that age at first calving was subjected to non-genetic factors. Season of calving did not affect significantly to this trait under study. Effect of season of calving was not significant on age at first calving indicating breed characteristic to adoption with environment. Age at first calving showed a significant rise over the period that indicate some selection measure require for age at first calving.

The production records on 345 Gir cows with 680 complete lactations sired by 52 bulls, for 24 years (1987–2010) were studied. The data were analyzed to study the effect of period and season of calving and parity as  xed effect on lactation milk yield (LMY). The least-squares mean of LMY was 2276.60±171.32 kg. Highly signi cant effect of period of calving and parity on LMY was observed. There were highest LMY during  fth parity (2694.20±184.94 kg.) and signi cant drop after eighth parity. Season of calving did not affect signi cantly LMY, which is one of the best attributes of Gir cattle.

The main objective of this study was to estimate genetic and environmental correlations between Age at First Calving and various production traits in Gir cattle. The production traits studied were: Standard Lactation Milk Yield, Peak Milk Yield, Lactation Length and Dry Period. The production records on 345 Gir cows with 1257 lactations sired by 52 bulls, maintained at Cattle Breeding Farm, Junagadh, Gujarat, over 24 years (1987–2010) were studied. The analysis revealed positive environmental correlation of Age at First Calving with Lactation Length (0.224 ± 0.234) and Dry Period (0.039 ± 0.195), while negative environmental correlation of Age at First Calving with Standard Lactation Milk Yield (-0.194 ± 0.178) and Peak Milk Yield (-0.070 ± 0.200). Genetic correlation of Age at First Calving with Standard Lactation Milk Yield (0.006 ± 0.178), Peak Milk Yield (0.069 ± 0.200), Lactation Length (0.752 ± 0.234) and Dry Period (0.058 ± 0.195) were found during this study, in which genetic correlation between Age at First Calving and Lactation Length was found highly significant. These indicated that selection for Age at First Calving would not reflect upon Standard Lactation Milk Yield and Peak Milk Yield.

The first lactation records of 1450 Gir cattle progeny of 290 dams and 41 sires maintained over the period from 1987 to 2010 at Cattle Breeding Farm, Junagadh Agricultural University, Junagadh, Gujarat were used to estimate the phenotypic, genetic and environmental trends of traits viz. first lactation total milk yield (FLTMY), first lactation total milk yield per day of first calving interval (FLTMY/FCI), first lactation total milk yield per day of first lactation length (FLTMY/FLL). The phenotypic trends were estimated as: 90.70 ± 6.44 kg, 0.24 ± 0.01 kg and 0.32 ± 0.02 kg for FLTMY, FLTMY/FCI and FLTMY/FLL respectively. The genetic trends were compared by five methods as Smith method1 (SM1), Smith method 2(SM2), Powell and Freeman method 1 (PM1), Powell and Freeman method 2 (PM2) and BLUP. The annual genetic trends for FLTMY were found to be positive by SM1 (2.88 ± 39.58 kg), PM1 (2.21 ± 37.34 kg) and BLUP (9.17 ± 1.94 kg). The annual genetic trends for FLMY/FCI were positive by SM1 (0.43 ± 0.03 kg), SM2 (2.69 ± 0.03 kg), PM1 (0.38 ± 0.02 kg) and PM2 (2.06 ± 0.02kg) while negative by BLUP (-0.05 ± 0.01 kg). The annual genetic trends for FLMY/FLL were found to be positive by SM1 (0.51 ± 0.06 kg) and PM1 (0.45 ± 0.03 kg) methods while negative by SM2 (-2.37 ± 0.05 kg), PM2 (-1.79 ± 0.03 kg) and BLUP (-0.06 ± 0.01 kg). However, the estimates obtained by BLUP method had the lowest standard errors and were more reliable compared to other methods.

Karyotypes, to study the basic chromosomal characteristics, of 6 male and 3 female Surti buffaloes maintained at Livestock Research Station, Navsari Agricultural University, Navsari were prepared. Short term lymphocyte culture technique was used to prepare the karyotypes. The karyotypes were studied for numerical abnormalities and relative length (%) as well as centromeric index of each chromosome. Diploid number of the chromosomes were found to be 50 including XY in males and XX chromosomes in females. Each karyotype consisted of 5 pairs of submetacentric and 19 pairs of acrocentric chromosomes. X chromosome was found to be the largest acrocentric chromosome. The relative length of chromosome no. 1 was found to be highest in both males and females, while that of Y chromosome was found to be least in males.

The production records on 680 Gir cows with 1257 lactations sired by 52 bulls, maintained at Cattle Breeding Farm, Junagadh, Gujarat, for 24 years were analyzed for heritability estimation of Lactation Milk Yield(LMY), 300 days milk yield(300dMY), Peak milk yield(PMY), Lactation length(LL), Dry period(DP), Calving interval(CI) and Age at  rst calving(AFC). The analysis revealed AFC (0.595 ± 0.073) was highly heritable trait, LMY (0.178 ± 0.480) and 300dMY (0.201 ± 0.050) were moderately heritable while PMY (0.116 ± 0.040), LL (0.046 ± 0.030), DP (0.129 ± 0.042) and CI (0.068 ± 0.033) were found with low heritability estimates.

Surti and Jaffarabadi buffaloes 10 each maintained at Livestock Research Station, Navsari and Cattle Breeding Farm, Junagadh, respectively were selected for the study. Milk samples were collected from each selected buffalo at day 15 and 60 postpartum (pp). The data of milk yield was recorded daily till day 60 pp in both the populations. Milk composition of samples viz. protein, fat, solid not fat and lactose percent were analyzed at day 15 and 60 pp. It was observed that Jaffarabadi buffaloes produced significantly higher milk in terms of test day milk yield and fat and protein corrected test day milk yield as compared to Surti buffaloes at day 15 and 60 pp. Jaffarabadi buffaloes were also found to be superior for fat, SNF, protein and lactose content during early lactation while for fat and protein content at 60 day pp as compared to those of Surti buffaloes. SNF percent showed significantly high positive correlation with protein and lactose percent at 60 day pp milk in both buffalo breeds.

P element wimpy testis-induced (Piwi)-interacting RNAs, popularly known as piRNAs, are one of the most recently identified small non coding class of RNAs. Because of their association with Piwi proteins, they are known as piRNAs. These molecules are reported to have the sequence length of 23 – 31 nucleotides with abundant expression in the testis. The origin of these molecules takes place from the piRNA clusters located on the genome. The biogenesis of these molecules takes place in two steps beginning with Primary Pathway followed by Ping-Pong cycle, with certain exceptions. The molecules play an important role in germline stability by silencing transposable and non transposable elements, epigenetic regulations, DNA methylation, long term memory functions and canalization. There are many aspects of piRNA, including biogenesis and functionality, the clear understanding of which requires more studies. This review summarizes the facts of piRNAs, genomics of piRNAs, apart from their biogenesis and functionality part, reported till date.

The records of 457 Surti buffaloes with 1346 lactations sired by 35 sires maintained at Livestock Research Station, Navsari Agricultural University, Navsari born during 1987 to 2012 were collected and analysed to examine the effect of non-genetic factors viz. season and period of birth on age at first calving. The average age at first calving in Surti buffaloes was found to be 1333.96 ± 19.53 days. The analysis of variance revealed highly significant effect of period of birth but non-significant effect of season of birth on age at first calving. No effect of season of birth on age at first calving indicated breed characteristics to acclimatize with environment. Age at first calving showed a significant rise during Period-2 (1993 to 1998) and Period-3 (1999 to 2004) and subsequent decline in Period-4 (2004-2012) indicates improvement of managemental practices over the periods of the farm.