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

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

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

<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

<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>

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

<div>Background: The livestock sector contributes nearly 17.1% of the value of output at current prices in Agriculture, Fishery and Forestry sector. The overall contribution of Livestock Sector in total GDP was nearly 5.1% during 2019-20. Dairying in India is witnessing transformation from traditional production system to either semi-commercial or commercial production system, which requires high producing dairy animals. Losses associated with milk fever are due to deaths, reduction in the productive lifespan of affected cow and reduction in milk production following each milk fever episode, as well as costs of prevention and treatment. It has been reported that about one in 20 affected cows, dies due to milk fever. Further, milk fever can contribute to dystocia, uterine prolapse, retained fetal membranes, metritis, abomasal displacement and mastitis leading to serious economic loss.&nbsp; 
 
Methods: A Jersey crossbred cow on its sixth parity was presented with the history indicated that the animal had calved 45 days ago and was semi-intensively managed. The daily production of milk was abou 15 liters. Physical examination revealed the temperature and pulse rate were within the normal range, but there was increased in respiratory rate and a dehydration status of 5%. The dairy cow was diagnosed with milk fever and treatment was done by slowly infusing 400 ml of Calcium borogluconate into the jugular vein over a period of 10-20 minutes. Intravenous infusion of 1000 ml 0.9% NaCl and 2000 ml of 25% glucose were instituted in order to restore blood glucose level and to correct the dehydration.&nbsp; 
 
Result: The animal recovered after the treatment, thus the prognosis was good and supportive therapy was continued for three days and animal had an uneventful recovery.</div>

<div>Medical Management of Milk Fever in a Crossbred Cow</div>

<div>Background: Genotype environment interaction plays vital role in animal productivity. Heat stress is one of the major environmental stressor affecting milk production and measured in terms of temperature humidity index (THI). Indian milk industry largely depends on crossbred cows bearing different degree of exotic inheritance. Thus, the role of genotype (genetic group) of the crossbred cows and environment (THI) interaction plays vital role in Indian climate which is mostly tropical in nature. Therefore, study was undertaken to examine the existence of genetic group &times; THI in crossbred dairy cows reared at institute herd of ICAR-National Dairy Research Institute, Eastern Regional Station, Kalyani, West Bengal.&nbsp; 
 
Methods: A total of 12364 records each of monthly milk yield (MMY) and average daily milk yield in a month (AMY) of crossbred cows spanned over twenty two years (1994-2015) and weather parameters(temperature and relative humidity) for the corresponding years were collected from institute records. The data were classified into 8 genetic groups according to the genetic composition and 3 THI groups (THI &lt;72, THI 72-78 and THI above 78). The interaction model was used to study the G&times;E interaction study using least squares analysis.&nbsp; 
 
Result: Effect of non-genetic factors (parity, period of calving and stage of lactation) was found to be highly significant (P&lt;0.01) and genetic group &times; THI was significant (P&lt;0.05) of on both MMY and AMY. Genetic group bearing 50% Jersey and 50% Red Sindhi or Tharparkar were the most heat tolerant breeds. Jersey crossbred cows were more heat tolerant than Holstein crossbred cows. Crossbred cows with 50% Jersey inheritance performed better than higher Jersey inheritance during periods of THI above 72.</div>

Genotype Environment Interaction on Milk Production Traits of Crossbred Dairy Cows under Tropical Climatic Condition of India

<div>Background: Various mathematical models have been tried by different researchers to fit the lactation curves in indigenous, exotic and crossbred cows maintained in organised farms only. Hence, this study was aimed to fit various lactation models and to identify the best fit model (s) for prediction of milk production in crossbred dairy cows in field conditions. 
 
Methods: Multistage random sampling procedure was used for selection of 100 dairy cows for the purpose of data collection. The monthly milk yield data (up to 10 months of lactation) of the selected crossbred cows reared in field conditions of Tamil Nadu State, relating to the period from 2017-20, were collected for lactation curve modelling. The milk data so collected were used to fit 14 lactation curve models in the study. The highest Coefficient of Determination (R&sup2;) value and the least Root Mean Square Error (RMSE) value were used as the criteria to select the best fit model(s). 
 
Result: The overall average total milk production was estimated to be 2223.19 kg per lactation in 10 months of lactation in the selected crossbred cows. Average daily milk yield at the first month of lactation was 9.16 kg and the highest daily milk yield of 9.56 kg was observed at the second month of lactation. At the end of the lactation, the lowest yield was 5.01 kg per day and hence the overall average daily milk yield was found to be 7.41 kg. Based on the selection criteria, the Mitscherlich X Exponential model was identified as the best fit model, followed by Ali and Schaeffer and Morant and Gnanasakthy model for prediction of milk production in crossbred dairy cows reared in field conditions and the estimated lactation curve model parameters a, b, c and d values for the best fit model were 331.71, 1519.82, 9.56 and 0.07 kg, respectively.&nbsp;</div>

<div>Comparative Evaluation of Lactation Curves of Crossbred Dairy Cows in Field Conditions in Tamil Nadu, India&nbsp;</div>

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: Milking behaviour of dairy cows has remarkable influences on their production efficacy. A number of genetic and environmental features controls and affects lactating behaviour of dairy cow. The aim of present study was to investigate the influence of seasons on milking behaviour and milk production of Jersey crossbred cows in tropical climate. 
 
Methods: The experiment was conducted on 94 Jersey crossbred cows maintained at organized dairy farm at ICAR-National Dairy Research Institute, Eastern Regional Station, Kalyani, West Bengal, India and there lactating behavioural features were studied during milking time inside the milking parlour under different seasons. The study period was divided into 3 season&rsquo;s viz. rainy (September-October), winter (November-February) and summer (March-May). 
 
Result: Seasons showed influence upon milking behaviour and milk yield of cows. Temperament of cows were least (1.91&plusmn;0.03) during winter seasons as compare to rainy and summer (2.15&plusmn;0.03; 2.09&plusmn;0.03) respectively and it differed significantly (P&lt;0.01), simultaneously daily milk yield were also more (9.36&plusmn;0.11) kgs during winter seasons as compare to rainy and summer (6.63&plusmn;0.13; 8.58&plusmn;0.13) respectively and it differed significantly (P&lt;0.01). It can be concluded from the study that seasons showed significant influence on the milking behavioural features and milk yield in Jersey crossbred cows in tropical climate, which suggests that if dairy animals get favourable micro-climatic environment and reduced level of environmental stress they will behave more favourably and simultaneously their production efficacy also inclines.</div>

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

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

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

Effect of Seasons on Physiological Responses in Sahiwal and Crossbred Cows

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

Medical Management of Milk Fever in a Crossbred Cow

Genotype Environment Interaction on Milk Production Traits of Crossbred Dairy Cows under Tropical Climatic Condition of India

Comparative Evaluation of Lactation Curves of Crossbred Dairy Cows in Field Conditions in Tamil Nadu, India

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

Effect of Seasons on Expressions of Milking Parlour Behaviours and Milk Yield of Crossbred Jersey Cows in Tropical Climate