A K Chakravarty

Identification of putative fertility markers in seminal plasma of crossbred bulls through differential proteomics

Sub-fertility is a major problem in crossbred bulls leading to disintegration of breeding systems and huge economic loss. Identification of some potential biomarkers to determine the latent fertility of bulls accurately has long been the interest of researchers. In this study, we analyzed the proteome of seminal plasma (SP) from bulls with varying fertility to identify the fertility-associated proteins. The proteomic profile of high- and low-fertile bulls was compared by two-dimensional difference gel electrophoresis and differentially expressed proteins were identified through matrix-assisted laser desorption/ionization-time of flight/mass spectrometry. Out of the 18 differentially expressed proteins (P < 0.05), 9 were overexpressed in SP of high-fertile bulls and 9 were overexpressed in SP of low-fertile bulls. The differential expressions ranged from 1.5- to 5.5-fold between the two groups, where protection of telomeres-1 protein (POT1) was highly overexpressed (2.9-fold) in high-fertile group and prostaglandin E2 receptor EP3 (PTGER3) was highly abundant (5.5-fold) in low-fertile group. The protein interaction network was elucidated using STRING software tool, and the functional bioinformatics analysis was done using Blast2Go software. Most of the differentially expressed proteins were found to be involved in cellular processes and biological regulation with binding and catalytic function. It is inferred that the expression of certain proteins in the SP varied with bull fertility, and concurrent appraisal of their expression along with other fertility assays may help in determining bull fertility.

Effect of heat stress on reproductive performances of dairy cattle and buffaloes: A review

Heat stress has adverse effects on the reproductive performances of dairy cattle and buffaloes. The dairy sector is a more vulnerable to global warming and climate change. The temperature humidity index (THI) is the widely used index to measure the magnitude of heat stress in animals. The objective of this paper was to assess the decline in performances of reproductive traits such as service period, conception rate and pregnancy rate of dairy cattle and buffaloes with respect to increase in THI. The review stated that service period in cattle is affected by season of calving for which cows calved in summer had the longest service period. The conception rate and pregnancy rate in dairy cattle were found decreased above THI 72 while a significant decline in reproductive performances of buffaloes was observed above threshold THI 75. The non-heat stress zone (HSZ) (October to March) is favorable for optimum reproductive performance, while fertility is depressed in HSZ (April to September) and critical HSZ (CHSZ) (May and June). Heat stress in animals has been associated with reduced fertility through its deleterious impact on oocyte maturation and early embryo development. The management strategies viz., nutrition modification, environment modification and timed artificial insemination protocol are to be strictly operated to ameliorate the adverse effects of heat stress in cattle and buffaloes during CHSZ to improve their fertility. The identification of genes associated with heat tolerance, its incorporation into breeding program and the inclusion of THI covariate effects in selection index should be targeted for genetic evaluation of dairy animals in the hot climate.

Genome-wide profiling of sperm DNA methylation in relation to buffalo (Bubalus bubalis) bull fertility

The DNA methylation pattern in spermatozoa of buffalo bulls of different fertility status was investigated. Spermatozoa isolated DNA from two groups of buffalo bulls (n = 5), selected based on their artificial insemination-generated conception rate data followed by IVF efficiency, were studied for global methylation changes using a custom-designed 180 K buffalo (Bubalus bubalis) CpG island/promoter microarray. A total of 96 individual genes with another 55 genes covered under CpG islands were found differentially methylated in sperm of high-fertile and subfertile buffalo bulls. Important genes associated with biological processes, cellular components, and functions were identified to be differentially methylated in buffalo bulls with differential fertility status. The identified differentially methylated genes were found to be involved in germ cell development, spermatogenesis, capacitation, and embryonic development. The observations hint that methylation defects of sperm DNA may play a crucial role in determining the fertility of breeding bulls. This growing field of sperm epigenetics will be of great benefit in understanding the graded fertility conditions of breeding bulls in commercial livestock production system.

Effects of pedigree and exotic genetic inheritance on semen production traits of dairy bulls

Abstract Objective To study the effects of different levels of exotic inheritance on ejaculate quality in bulls and its passage through different generations. Methods Data on semen production traits and ejaculate quality were obtained for 38 crossbred bulls and grandsire-sire-progeny relationship in relation to semen quality was studied. The bulls were classified into three groups based on the level of exotic inheritance viz. F1, 50.0%-62.5% exotic germplasm and >75% exotic germplasm. Results Results of the present study indicated that about 40% of the ejaculates obtained from the crossbred bulls were rejected from further processing due to poor ejaculate quality. The F1 bulls produced significantly higher proportions (57.00±10.00) of poor quality ejaculates compared to the interse mated bulls. The age at first semen collection in crossbred bulls ranged from 567 to 1 010 days with an average of 738.89±18.18 days while the mean age at first semen freezing was 865.72±34.60 days. Conclusions It may be inferred that the “acceptable quality semen producing ability” decreased from grandsire through sire to male progeny and among the increasing exotic genetic levels of CB cattle, F1 bulls produced significantly higher “low grade ejaculates” that were unfit for cryopreservation.

Molecular Characterization and SNP Detection of CD14 Gene of Crossbred Cattle

CD14 is an important molecule for innate immunity that can act against a wide range of pathogens. The present paper has characterized CD14 gene of crossbred (CB) cattle (Bos indicus×Bos taurus). Cloning and sequence analysis of CD14 cDNA revealed 1119 nucleotide long open reading frame encoding 373 amino acids protein and 20 amino acids signal peptide. CB cattle CD14 gene exhibited a high percentage of nucleotide identity (59.3–98.1%) with the corresponding mammalian homologs. Cattle and buffalo appear to have diverged from a common ancestor in phylogenetic analysis. 25 SNPs with 17 amino acid changes were newly reported and the site for mutational hot-spot was detected in CB cattle CD14 gene. Non-synonymous substitutions exceeding synonymous substitutions indicate the evolution of this protein through positive selection among domestic animals. Predicted protein structures obtained from deduced amino acid sequence indicated CB cattle CD14 molecule to be a receptor with horse shoe-shaped structure. The sites for LPS binding, LPS signalling, leucine-rich repeats, putative N-linked glycosylation, O-linked glycosylation, glycosyl phosphatidyl inositol anchor, disulphide bridges, alpha helix, beta strand, leucine rich nuclear export signal, leucine zipper and domain linker were predicted. Most of leucine and cysteine residues remain conserved across the species.

Effect of lameness (hoof disorders) on productivity of Karan Fries crossbred cows

In present study production performance of 96 lame cows was compared with 67 healthy cows. No significant effect of parity and year of calving on milk yield were observed but the effect of season of calving was significant (P < 0.01). Effect of lameness on milk yield at the second, third and fourth months and 305 days was highly significant (P < 0.01), and was also significant (P < 0.05) on lactation yield of the fifth and tenth months. The effect of lameness on monthly and 305-day milk yield was significant (P < 0.01) only for those cows diagnosed lame before calving and during the first month of lactation. The differences in mean monthly yield were highly significant (P < 0.01) at the second, third and fourth months; and significant (P < 0.05) in the first and fifth months. The loss in the first lactation month of cows which were diagnosed as lame in the second month, was found to be significant (P < 0.05). Thus the yield of the month previous to the diagnosis (sub-clinical stage) was also affected. A significant (P < 0.01) total loss of 498.95 kg of milk yield was observed during a period of 305 days.

POLYMORPHISM OF GROWTH HORMONE GENE AND ITS ASSOCIATION WITH EXPECTED MILK PRODUCTION TRAITS IN DAIRY BULLS

Abstract Pal, A., Chakravarty, A.K., Bhattacharya, T.K. and Sharma, A. 2005. Polymorphism of growth hormone gene and its association with expected milk production traits in dairy bulls. J. Appl. Anim. Res., 27: 29–33. To explore polymorphism in 4th exon, 4th intron and 5th exon of growth hormone gene in Karan Fries (KF) cattle and Murrah buffalo bulls and its association with expected milk producing ability, a 428 bp fragment was amplified and digested with Alu I restriction enzyme. Two alleles L and V corresponding to leucine and valine variant of growth hormone polypeptide and thus two genotypes LL and LV were identified in Karan Fries bulls, whereas only LL genotype was observed in Murrah bulls. Karan Fries bulls with LL genotype were found to have higher (P≤0.01) expected predicted difference with respect to milk production traits as compared to the LV heterozygotes.

Assessment of expected breeding values for fertility traits of Murrah buffaloes under subtropical climate

Aim: The aim of the present study was to assess the influence of temperature and humidity prevalent under subtropical climate on the breeding values for fertility traits viz. service period (SP), pregnancy rate (PR) and conception rate (CR) of Murrah buffaloes in National Dairy Research Institute (NDRI) herd. Materials and Methods: Fertility data on 1379 records of 581 Murrah buffaloes spread over four lactations and climatic parameters viz. dry bulb temperature and relative humidity (RH) spanned over 20 years (1993-2012) were collected from NDRI and Central Soil and Salinity Research Institute, Karnal, India. Monthly average temperature humidity index (THI) values were estimated. Threshold THI value affecting fertility traits was identified by fixed least-squares model analysis. Three zones of non-heat stress, heat stress and critical heat stress zones were developed in a year. The genetic parameters heritability (h2) and repeatability (r) of each fertility trait were estimated. Genetic evaluation of Murrah buffaloes was performed in each zone with respect to their expected breeding values (EBV) for fertility traits. Results: Effect of THI was found significant (p<0.001) on all fertility traits with threshold THI value identified as 75. Based on THI values, a year was classified into three zones: Non heat stress zone(THI 56.71-73.21), HSZ (THI 75.39-81.60) and critical HSZ (THI 80.27-81.60). The EBVfor SP, PR, CR were estimated as 138.57 days, 0.362 and 69.02% in non-HSZ while in HSZ EBV were found as 139.62 days, 0.358 and 68.81%, respectively. EBV for SP was increased to 140.92 days and for PR and CR, it was declined to 0.357 and 68.71% in critical HSZ. Conclusion: The negative effect of THI was observed on EBV of fertility traits under the non-HSZ and critical HSZ Thus, the influence of THI should be adjusted before estimating the breeding values for fertility traits in Murrah buffaloes.

Differential Histone Modification Status of Spermatozoa in Relation to Fertility of Buffalo Bulls

In this study genome‐wide di‐methylated H3K4 (H3K4me2) and tri‐methylated H3K27 (H3K27me3) modification profiles were analyzed in spermatozoa of buffalo bulls having wide fertility differences. The custom designed 4 × 180 K buffalo (Bubalus bubalis) ChIP‐on‐chip array was fabricated by employing array‐based sequential hybridization using bovine and buffalo genomic DNA for comparative hybridization. The buffalo specific array developed had 177,440 features assembled from Coding sequences, Promoter and CpG regions comprising 2967 unique genes. A total of 84 genes for H3K4me2 and 80 genes for H3K27me3 were found differentially enriched in mature sperm of high and sub‐fertile buffalo bulls. Gene Ontology analysis of these genes revealed their association with different cellular functions and biological processes. Genes identified as differentially enriched between high and sub‐fertile bulls were found to be involved in the processes of germ cell development, spermatogenesis and embryonic development. This study presents the first genome‐wide H3K4me2 and H3K27me3 profiling of buffalo bull sperm. Results provide a list of specific genes which could be made responsible for differential bull fertility. J. Cell. Biochem. 116: 743–753, 2015.

Polymorphism of growth hormone gene and its association with seminal and sexual behavioral traits in crossbred cattle

The decline in the male reproductive ability in terms of sexual behavior and seminal traits might lead to nonavailability of required number of bulls in a progeny testing program. The present study was conducted in 493 crossbred cattle (Bos taurus × Bos indicus) bulls to study polymorphisms of growth hormone (GH) gene and its association with seminal and sexual behavioral characteristics. A 428-base pair fragment of GH gene spanning over the fourth exon, fourth intron, and fifth exon was amplified and digested with AluI restriction enzyme. Bulls were found to be polymorphic, with two variants, LL and LV, and higher genotypic frequency for LL being 0.88. Twelve nucleotide changes and a single nonsynonymous substitution of Leucine by Valine were observed from GH1 (L) to GH2 (V). Statistical analysis revealed that the genotype of the GH gene had a significant effect on libido score, reaction time, Flehmen response, requirement of mounting stimulus, sperm mass activity, number of semen doses per collection, individual fresh sperm motility, postthaw sperm motility, acrosome integrity, hypo-osmotic swelling test, live and dead count, total morphological abnormality, and head abnormality of sperm in crossbred bulls. Growth hormone gene might be considered a candidate gene for seminal and sexual behavioral traits in crossbred cattle.