The study was undertaken to determine the composition of colostrum and milk of Hill cattle during postpartum period and compared them to Sahiwal and crossbred cow. Fifteen colostrum samples per day from each group of cow (as per availability) were collected during first five postpartum days while as milk samples were collected from eight cow each of Sahiwal and crossbreds and six form Hill cow, at fortnightly interval up to 32 weeks postpartum. These samples were subjected to various physico-chemical analyses. There was a significant (P0.05) difference between overall mean protein per cent, pH and electrical conductivity in the colostrum of Hill cow, Sahiwal and crossbred cow but lactose per cent did not diffe significantly. In milk there was a significant (P0.05) difference between overall mean of fat, protein, solid not fat, total solids per cent, pH, electric conductivity, somatic cell count and milk yield of Hill cow, Sahiwal and crossbreds while non-significant (P0.05) difference was noticed for lactose per cent and specific gravity. The colostrum of Hill cow and Sahiwal were richer in protein, fat, lactose, TS and ash content as compared to crossbred cow. Milk of Hill cow had higher content of protein, fat, SNF, TS and lower pH, EC and SCC compared to crossbreds and Sahiwal.

Colostrum and milk composition during postpartum period in Hill cow, sahiwal and crossbreds cow

<div>Background: Growing demand for improving milk production and rising temperatures due to global warming has increased the thermal load on dairy animals. Physiological parameters such as respiration rate and body temperature mainly determine the adaptability of animals to climate stress. During genetic adaptation, Bos indicus cattle have acquired thermo tolerant genes and when exposed to heat stress conditions, the Bos indicus cattle have lower respiration rates and rectal temperatures than Bos taurus animals. The present study was aimed to study the effect of seasons on the physiological responses in Sahiwal and crossbred cows. 
 
Methods: A total of 50 crossbred cows maintained at Military dairy Farm, Secunderabad and 50 Sahiwal cows maintained at Livestock Farm Complex, College of Veterinary Science, Rajendranagar, PVNRTVU were utilized for the present investigation. The study was conducted during summer (THI = 83.71&plusmn;0.01), rainy (THI = 71.37&plusmn;0.01) and winter (THI = 66.69&plusmn;0.01) seasons. Changes in respiration rate (RR), rectal temperature (RT) and heat tolerance coefficient (HTC) were observed in different seasons in Sahiwal and crossbred cows. 
 
Result: RR (breaths/ min) in Sahiwal cows during summer, rainy and winter were 28.56&plusmn;0.38, 23.38&plusmn;0.38 and 20.54&plusmn;0.38 respectively whereas RR (breaths/ min) in crossbred cows were 44.58&plusmn;0.38, 25.94&plusmn;0.38 and 21.90&plusmn;0.38 respectively. In Sahiwal cows RT (&deg;C) during summer, rainy and winter were 38.52&plusmn;0.03, 38.23&plusmn;0.03 and 38.13&plusmn;0.03 respectively whereas RT (&deg;C) in crossbred cows were 39.22&plusmn;0.02, 38.72&plusmn;0.03 and 37.80&plusmn;0.03 respectively. The magnitude of increase in RR, RT and HTC were found to be higher during summer compared to other seasons in both Sahiwal and crossbred cows. It was observed that Sahiwal cows are less sensitive to heat stress and are better able to regulate their body temperature than crossbred cows when environmental temperature increases during summer. The HTC values were lower in Sahiwal cows in all the seasons studied indicating better thermo tolerance when compared to the crossbred cows.</div>

Effect of Seasons on Physiological Responses in Sahiwal and Crossbred Cows

Background: Cellular tolerance to heat stress is mediated by heat shock proteins (HSPs). The HSPs act as molecular chaperones and are transcribed in response to stress. Among different families of these proteins, HSP70 is considered to be related to the development of temperature tolerance. Unraveling polymorphism in heat shock protein genes could be a step towards the identification of genetic markers for selecting heat-tolerant cattle.&nbsp; 
 
Methods: The present study was carried out in Sahiwal (n=50) and Crossbred cows (n=50) with the objective to identify polymorphisms in HSP70 gene. Two fragments (295 and 220 bp) of HSP70 gene were subjected to Polymerase Chain Reaction-Single-Strand Conformation Polymorphism (PCR-SSCP) technique. Statistical analysis was performed to study the association of each SSCP genotype on physiological, production and reproduction traits in Sahiwal and crossbred cows using the univariate GLM model of SPSS 25. 
 
Result: The PCR-SSCP of 295 bp fragment of HSP70 gene revealed two genotypes AA and AB in Sahiwal cows and two genotypes AA and AC in crossbred cows. The association analysis revealed that genotype AA had higher peak milk yield in Sahiwal cows while the same genotype had higher total lactation milk yield, lower service period and calving interval in crossbred cows. The 220 bp fragment was found to be monomorphic in both Sahiwal and crossbred cows.&nbsp;

Association of SSCP Polymorphisms of HSP70 Gene with Physiological, Production and Reproduction Performance in Sahiwal and Crossbred Cows

<div>Background: Beta-carotene (BETA) is a precursor of retinol (Vitamin A) and positively influenced on reproductive efficiency in cows. The aim of the study was to determine the effect of orally supplementation of beta-carotene on plasma carotene content and fertility rate of lactating crossbred Sahiwal cows. 
 
Methods: Twenty-four disease-free lactating crossbred Sahiwal cows with a close date of calving were randomly divided into two homogeneous groups for Control group (CONT; n = 12) and Beta-carotene group: 500 mg/cow/d (BETA; n = 12) from 7 days post partum (dpp) until 105 dpp thereafter on concentrations of beta-carotene and selected protein and energy parameters in plasma were determined. In addition, effects on fertility rate were studied. 
 
Result: Beta-carotene concentrations increased in plasma of beta-carotene (BETA-group) supplemented cows compared to control (CONT-group) cows (p&lt;0.001). In BETA-group cows, urea concentration in blood plasma decreased significantly compared to cows of CONT-group (p&lt;0.001) but did not differ in total protein, albumin, glucose and total cholesterol content in cows of both groups. Occurrence of first post partum estrus decreased (p&lt;0.001) in beta-carotene (BETA-group: 74 dpp) cows compared to control (CONT-group: 81 dpp) cows. In this study, it was observed that the overall conception rate was higher (p&gt;0.001) in BETA-group: 83.33% (cows pregnant: 10/12) and lesser in the CONT-group: 50.00% (cows pregnant: 6/12). The results of this study indicated that oral supplementation with beta-carotene increased the concentration of beta-carotene and decreased the concentration of urea in plasma and cows with higher blood plasma beta-carotene content improved fertility over cows with lower blood plasma beta-carotene content.</div>

​Effect of Beta-carotene Supplementation on Plasma Carotene Content and Fertility of Lactating Crossbred Sahiwal Cows

<div>Background: Heat shock proteins (HSPs) are molecular chaperones that play a critical role in recovering cells from stress and form a primary system for intra cellular self defense. They are highly conserved and play a crucial role in cellular thermo tolerance and heat stress response. Though there are many HSP genes, thermo tolerance is mainly correlated with HSP70 and HSP90 genes in Livestock species. Polymorphisms in these genes have shown an association with heat tolerance, milk production, fertility and disease susceptibility in livestock. They can be used as genetic markers for the selection of animals with better climate resilience, immune response and superior performance. 
 
Methods: The present study was carried out in Sahiwal (n=50) and Crossbred cows (n=50) with the objective to identify polymorphisms in HSP90AA1 gene. A 450 bp fragment of bovine HSP90AA1 gene covering exon3 was subjected to Polymerase Chain Reaction-Single-Strand Conformation Polymorphism (PCR-SSCP) technique to identify the polymorphism. PCR-SSCP patterns were correlated with the physiological, productive and reproductive traits in Sahiwal and crossbred cows using the univariate GLM model of SPSS 25. 
 
Result: The PCR-SSCP of exon 3 of HSP90AA1 gene yielded two conformational patterns AA and AB corresponding to two allelic variants A and B in both Sahiwal and crossbred cows. The allele frequencies of A and B were 0.78 and 0.22 and 0.84 and 0.16 in Sahiwal and crossbred cows, respectively. The association analysis of SSCP patterns revealed that genotype AA had higher lactation length in Sahiwal cows and higher total lactation milk yield and peak yield in crossbred cows.&nbsp;</div>

​Genetic Polymorphism within Exon 3 of HSP90AA1 Gene&nbsp;and its Association Studies in Sahiwal and Crossbred Cows

<div>Background: Milk production is one of the most important economic traits in dairy cattle. Crossing of zebu cattle (Bos indicus) with temperate cattle breeds (Bos taurus) was undertaken to improve the milk production in India. Crossbreeding has resulted in improved production performance of the dairy animlas over the past few decades. 
 
Methods: Data on 50 purebred Sahiwal cows from the Livestock Farm Complex, College of Veterinary Science, Rajendranagar, Hyderabad and 50 Holstein Friesian &times; Sahiwal crossbred cows maintained at the Military Dairy Farm, Secunderabad were utilized to study the influence of breed and parity on various production and reproduction traits. The various traits studied were: Total lactation milk yield (TLMY) Lactation length (LL), Peak yield (PY), Age at first service (AFS), Age at first calving (AFC), Gestation period (GP), Service period (SP), Dry period (DP) and Calving interval (Cl). 
 
Result: In the present study, significant effect of breed was found on the TLMY and PY with the crossbreds recording higher values for both the traits. The means for TLMY, PY, LL, GP, SP, DP and CI were 1768.32&plusmn;109.67 kg, 10.17&plusmn;0.50 kg, 304.41&plusmn;13.00 days, 277.71&plusmn;2.24 days, 182.60&plusmn;15.51 days, 167.47&plusmn;10.68 days and 430.23&plusmn;13.46 days in Sahiwal and 2983.45&plusmn;78.32 kg, 14.92&plusmn;0.36 kg, 324.71&plusmn;9.29 days, 275.34 days, 181.09&plusmn;10.91 days, 127.01&plusmn;7.51, 413.61&plusmn;9.47 days in crossbred cows respectively. It may be concluded that the productive performance of crossbred cows was better than that of indigenous cows.</div>

Production and Reproduction Performance of Sahiwal and HF &times; Sahiwal Cows

The present study was undertaken on data of 150 Frieswal cows (a new strain of Sahiwal x Holstein Friesian) maintained at Military Dairy Farm, Agra, over a period of 15 years from 1996-2010, based on age at first calving. The overall means for age at first calving (AFC), weight at first calving (WFC), first lactation milk yield (FLMY), first lactation period (FLP), first dry period (FDP) and first calving interval (FCI) were 928.07&plusmn;0.08 days, 369.87&plusmn;0.92 kg, 4054.35&plusmn;22.14 litres, 301.84&plusmn;0.26 days, 99.40&plusmn;0.15 days and 401.33&plusmn;0.33 days respectively. The period of calving has significant &nbsp; influence on AFC and WFC, whereas non-significant influence on FLMY, FLP and FDP. The season showed significant influence on all the traits under study except FLMY. Both period and season has highly significant influence on FCI.

Study of productive traits in Sahiwal x Holstein Friesian crossbred cows &ndash; Frieswal

Mastitis is considered as one of the important production disease in dairy cows which incurs huge economic losses to dairy industry, despite considerable efforts has been dedicated to solve it for the last two decades. In the present study, the impact of dry cow therapy (DCT) on incidence of clinical mastitis, milk yield and composition in crossbred cows was studied. About 20 healthy crossbred cows were selected at dry-off and randomly allotted either to control or treatment group. Daily milk yield of cows was recorded up to 45 days post-partum and fortnightly separate quarter wise milk samples were collected for estimation of milk composition. While no quarter in the treatment group showed clinical mastitis, 33.33% of quarters in control group showed clinical mastitis within 45 days post-partum. Milk production increased by 9.71, 8.40 and 18.18% during first, second and third fortnight with overall value 11.84% during the entire 45 days post-calving period in DCT treated cows compared to control group. Also, the overall fat-corrected milk, solid-corrected milk and energy-corrected milk production following 45 days post-partum increased significantly (P&lt;0.05) by 22.71, 23.70 and 22.80%, respectively in treated group than control group. However, overall mean milk components such as fat, protein, lactose, SNF and TS remained similar between treatment and control groups. Taken together, the above results indicated that DCT increased milk yield by reducing incidence of clinical mastitis during early lactation.&nbsp;

Effect of dry cow therapy on incidence of clinical mastitis,&nbsp;milk yield and composition in crossbred cows

The karyological investigation using 16 purebred Sahiwal and 16 Jersey X Sahiwal cattle (8 males and 8 females of each genetic group) revealed the diploid chromosome number to be 60. All the 29 pairs of autosomes were acrocentric, while the X &ndash; chromosome was sub-metacentric in both the genetic groups. Acrocentric Y chromosome of Sahiwal differed from small submetacentric chromosome of Jersey X Sahiwal cattle in its morphology. The relative length of autosomes ranged from 1.74 &plusmn; 0.01 to 5.28 &plusmn; 0.02 in Sahiwal and from 1.72 &plusmn; 0.01 to 5.26 &plusmn; 0.02 in Jersey X Sahiwal crosses. X &ndash; Chromosome was the second largest chromosome in both the genetic groups. The contribution of &nbsp;X and Y chromosomes to the total genome were 5.07 and 1.99 per cent to the total genome in Sahiwal and 5.06 and 2.20 per cent &nbsp;in Jersey X Sahiwal cattle, respectively. The arm ratio, centromeric index and morphological index for the X-chromosome of Sahiwal and Jersey X Sahiwal cattle were 1.89, 0.35, 2.87 and 1.84, 0.36, 2.76, respectively. The arm ratio, centromeric index and morphological index for the Y-chromosome of Jersey X Sahiwal cattle were 1.63, 0.35 and 1.41, respectively.

Comparison of chromosomal architecture of Sahiwal&nbsp;and crossbred Sahiwal cattle

<div>Background: The objective of this study was to find out the association of lactation numbers of crossbred cow with their serum antisperm antibody titre, if any.&nbsp; 
 
Methods: Total 163 numbers of normal breeding crossbred jersey crossbred cows belong to various lactational groups maintained in the Instructional Livestock Farm, College of Veterinary Science, Assam Agricultural University, Khanapara and various private cattle farms in Kamrup district of Assam, India were selected for the work. ELISA was carried out for detection of antisperm antibody (asp-abs) in the test sera. Data were analysed using Chi-square test. 
 
Result: In the present study, out of 163 females 94 (57.67%) animal were found to be positive reactors. The percentage of positive reactors could be detected in 1st, 2nd, 3rd, 4th, 5th and above (5th, 6th, 7th and 9th) lactational group of cows were 16 (72.73%),15 (50.00%), 23 (63.89%), 14 (43.75%), 26 (60.47%) respectively. The highest titre up to the extent of 1:320 was recorded in the sera of cows with 1st, 3rd and 4th lactations. A negative correlation (r = -0.42NS) between the numbers of lactation and 
positive reactors for antisperm antibody (asp-abs) is found in crossbred cows.</div>

Colostrum and milk composition during postpartum period in Hill cow, sahiwal and crossbreds cow

Effect of Seasons on Physiological Responses in Sahiwal and Crossbred Cows

Association of SSCP Polymorphisms of HSP70 Gene with Physiological, Production and Reproduction Performance in Sahiwal and Crossbred Cows

Effect of Beta-carotene Supplementation on Plasma Carotene Content and Fertility of Lactating Crossbred Sahiwal Cows

Genetic Polymorphism within Exon 3 of HSP90AA1 Gene and its Association Studies in Sahiwal and Crossbred Cows

Production and Reproduction Performance of Sahiwal and HF × Sahiwal Cows

Study of productive traits in Sahiwal x Holstein Friesian crossbred cows – Frieswal

Effect of dry cow therapy on incidence of clinical mastitis, milk yield and composition in crossbred cows

Comparison of chromosomal architecture of Sahiwal and crossbred Sahiwal cattle

Association of Lactation Numbers of Crossbred Cows with Their Serum Antisperm Antibody Titre