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Genetic persistencies of milk yield up to six parities were estimated for the first time in India to assess the sustainability of Sahiwal cattle. Monthly test day milk yield records of Sahiwal catt...

Background: The selection of genetically superior animals at an early stage of life, the molecular markers are used along with traditional selection. The study was carried out to identify the genetic polymorphism in the exon3 region of the Prolactin and enumerate its effect on milk production performance in Sahiwal cattle. Prolactin plays an imperative regulatory role in mammary gland development, milk emission and lactogenesis. Analysed the sequence of this gene to explore whether mutations in this sequence and it could be accountable for quantitative variations in milk production and its composition traits.Methods: Total DNA was isolated from the blood samples of 98 pedigreed Sahiwal population. Using PCR-RFLP method and direct sequencing, noticed a single-nucleotide polymorphism in exon3 region of the Prolactin gene in 156bp and also the effect of non- genetic factors on each trait was assessed by least-squares analysis for non-orthogonal data by a fixed model.Result: PCR-RFLP was done with RsaI restriction endonuclease for the identification of different genotypes. The frequency of G and A alleles of the Prolactin gene was evaluated as 0.575 and 0.425, whereas the frequencies of GG, GA and AA genotypes for the Prolactin gene were 0.45, 0.25 and 0.30, respectively. SNP (G55A) conferred an increase in test-day milk yield around 321.5g, in test day fat yield around 13.9g and in test day SNF yield increase was 19.4g, respectively. High correlation was perceived from test day (TD2) onwards between test day traits and lactation milk yield indicating that selection based on identified SNP in TD2 increased test day milk yield, fat yield and SNF yield by 1.1472 kg, 29.6gm and 45.4gm, respectively.

Background: The estimates of genetic parameters are useful in determining the appropriate method of selection that could further be implemented in the breed improvement programmes. The present study was, therefore, conducted to estimate the genetic parameters (heritability, genetic and phenotypic correlations) for monthly test day (TD) milk yields, peak yield (PY) and first lactation 305 days milk yield (FL305DMY) in Murrah buffaloes.Methods: Paternal half-sib correlation method was carried out by least-squares maximum likelihood programme to estimate genetic parameters of first lactation 4,209 and 408 records of monthly test day milk yield and peak yield, respectively, of 408 Murrah buffaloes (sired by 62 bulls) calved in between 1993 and 2017 at ICAR-National Dairy Research Institute, Karnal.Result: Heritability of FL305DMY and peak yield was estimated as 0.35±0.17 and 0.33±0.16, respectively. Heritability estimates for mid-lactation monthly test day milk yields were found to be moderate. Genetic correlation of monthly test day milk yields with FL305DMY was positive and highly significant for TD-4 to TD-9 and TD-11. Peak yield showed high genetic and phenotypic association with FL305DMY. High genetic and phenotypic correlation among monthly test day milk yields, peak yield and FL305DMY suggested that TD-4 to TD-9 and TD-11 test day milk yields and peak yield could be used for the selection of elite animals.

This study was performed to investigate the polymorphisms in the ABCG2 (ATP-binding cassette sub-family G member 2) gene and to reveal the association of genotypes with breeding value (BV) for first lactation milk yield and milk composition traits of Karan Fries (HF crossbred) cattle. The traits were adjusted against the significant effect of non-genetic factors. PCR-RFLP analysis of ABCG2 (exon 14) gene revealed three genotypes. AA genotype in ABCG2 gene had significant effect on BV for average test day fat percentage. The identified potential genetic marker could be used for the development of Marker Assisted Selection (MAS) strategy for higher milk yield and milk composition traits in Karan Fries Cattle.

First lactation records of 351 Karan-Fries cows born to 27 bulls, having 3 or more progeny were used to evaluate sires by animal model (AM). Heritabilities, genetic and phenotypic correlations between the traits were estimated by univariate and bivariate linear animal models. The heritability estimates for 305 days or less milk yield (305MY), fat based energy corrected milk yield (FECMY), fat protein based energy corrected milk yield (FPECMY) and fat protein lactose based energy corrected milk yield (FPLECMY) were 0.23, 0.65, 0.11 and 0.39, respectively. There was a high (0.99) genetic and phenotypic correlation between 305MY, FECMY and FPLECMY. The high and positive genetic correlations between energy traits are indication of common genetic and physiological mechanism governing these traits. Comparison of ranks of the sires based on 305MY, FECMY and FPLECMY by animal model depicted a notable100 per cent level of similarity except for FPECMY in which the ranks were entirely different. There was a high heritability and genetic correlation between FECM and FPLECM. Genetic evaluation of Karan-Fries bulls based on energy corrected milk yield will increase the accuracy of selection than the conventional mil yield evaluation. It can help in mitigating the nutritional insecurity of the country in the long run.

Aim: The present study was performed to investigate the effect of genetic and non-genetic factors affecting milk fat yield and to estimate genetic parameters of monthly test day fat yields (MTDFY) and lactation 305-day fat yield (L305FY) in Murrah buffaloes. Materials and Methods: The data on total of 10381 MTDFY records comprising the first four lactations of 470 Murrah buffaloes calved from 1993 to 2014 were assessed. These buffaloes were sired by 75 bulls maintained in an organized farm at ICAR-National Dairy Research Institute, Karnal. Least squares maximum likelihood program was used to estimate genetic and non-genetic parameters. Heritability estimates were obtained using paternal half-sib correlation method. Genetic and phenotypic correlations among MTDFY, and 305-day fat yield were calculated from the analysis of variance and covariance matrix among sire groups. Results: The overall least squares mean of L305FY was found to be 175.74±4.12 kg. The least squares mean of overall MTDFY ranged from 3.33±0.14 kg (TD-11) to 7.06±0.17 kg (TD-3). The h 2 estimate of L305FY was found to be 0.33±0.16 in this study. The estimates of phenotypic and genetic correlations between 305-day fat yield and different MTDFY ranged from 0.32 to 0.48 and 0.51 to 0.99, respectively. Conclusions: In this study, all the genetic and non-genetic factors except age at the first calving group, significantly affected the traits under study. The estimates of phenotypic and genetic correlations of MTDFY with 305-day fat yield was generally higher in the MTDFY-5 of lactation suggesting that this TD yields could be used as the selection criteria for early evaluation and selection of Murrah buffaloes.

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.

A study was conducted on calving records of Murrah buffaloes to study the influence of various functional traits on subsequent reproductive performance. The effects of calving abnormalities, uterine health problems, female fertility problems and udder health problem on calving to first service (CFS), service period (SP), dry period (DP) and calving interval (CI) were studied by the least-squares method using the SAS package. The increase in CFS, SP, DP and CI was 27.07%, 18.71%, 96.74% and 6.70%, respectively. Subsequently, the average milk yield per day of calving interval was found to be reduced (from 4.91 to 2.10 kg/day) in these animals in comparison with the normal calvers. A highly significant increase in average CFS, SP, DP and CI was found among animals susceptible to metritis (16.93%, 73.88%, 53.92% and 20.04%, respectively). The decrease in average milk yield per day of calving interval (MY/CI) was 18.55% in comparison with the animals not affected by metritis. The average MY/CI was obse...

Early selection of bulls having optimum age at first semen freezing play an important role in improving reproductive performance in a dairy herd. Twenty seven years data (1987-2013) on age at first semen freezing (AAFSF), conception rate based on first A.I. (CRFAI) , overall conception rate (OCR) and birth weight (B.WT) of 41 Sahiwal bulls belonging to 8 sets of Sahiwal improvement programme at ICAR-National Dairy Research Institute, Karnal, Haryana, India; were adjusted against environmental effects and subsequently analysed. Simple and multiple regression models were used for prediction of CRFAI and OCR of Sahiwal bulls. Among the three developed models (I to III), it was observed that Model III having age at first semen freezing and birth weight fulfil the accuracy of model i.e.; having high coefficient of determination (R2) value (CRFAI = 67% and OCR= 69%), low mean error sum of square (MSSe), low conceptual predictive value (CP value) and low Bayesian information criterion (BIC). The results revealed that optimum age at first semen freezing of Sahiwal bulls should be 2.5 - 3.0 years for 3.10% higher conception rate based on first A.I. (48.86%) and 4.39% higher overall conception rate (48.78%) in comparison to Sahiwal bulls with more than 3.5 years of age (CRFAI :- 45.76% and OCR :- 44.39%).

The study was conducted to identify the genetic variability in exon 5 region of GH1 gene and quantify its effect on production performance in Karan Fries cattle.PCR-RFLP method using Alu I restriction endonuclease was used for identification of genotypes. LL and LVgenotypes with frequencies as 0.46 and 0.54 and the frequency of L allele as 0.73 were found. Season of calving was only found significant (p £0.05) for fat yield of TD3, TD6 and TD10. The effect of SNP of GH1 gene (exon 5) increased the overall test day milk yield, fat yield and SNF yield by 1.05 kg, 43.2 gm and 103 gm.High correlations were obtained from TD3 onwards between test day traits and lactation milk yield indicating that selection based on identified SNP in TD3 increased test day milk yield, fat yield and SNF yield by 2.5229 kg, 62.9 gm and 215.9 gm, respectively.

The present study was conducted to identify the most suitable temperature humidity index (THI) model among seven reported THI models for analyzing the impact of thermal stress on monthly test day fat % (MTDF%),monthly test day SNF% (MTSNF%), monthly test day fat yield (MTDFY) and monthly test day SNF yield (MTDSNFY) of Murrah buffaloes at subtropical climatic conditions of Karnal, India. A total of 8868 MTDF% and 8606 MTDSNF% records from 1107 lactational records of Murrah buffaloes under five parities were included in the present study and weather information on dry bulb temperature (Tdb), wet bulb temperature (Twb) and relative humidity (RH in %) for the corresponding period of 20 years (March 1994- December 2013) were collected from ICAR-NDRI and ICAR-CSSRI, Karnal, respectively. The overall least-squares means for MTDF% ranged from 7.71 ± 0.067 in TD1 to 8.10 ± 0.08 in TD 9 and MTDSNF% ranged from 9.61 ± 0.01 in TD5 and TD 6 to 9.65 ± 0.01 in TD 8. The overall least squares means of MTDFY (g) ranged from 411.23 ± 14.74 to 745.98 ± 13.57 while for MTDSNFY (g) the value ranged from 491.90 ± 17.21 to 922.16 ± 15.17. Monthly average THI was computed for each of the seven models. The lowest monthly average THI value was found in January, while either May, June or July showed the highest average THI value for all seven THI models. Regression analysis was performed for identifying the best THI to assess the impact of heat stress on milk constituent traits under study anda negative association was found between the milk constituent traits and monthly average THI values.The THI model[THI = (0.55 × Tdb + 0.2 × Tdp) × 1.8 + 32 + 17.5]developed by NRC(1971)was identified as the most suitable THI model to assess the impact of heat stress on milk composition traits of Murrah indicating maximum decline in MTDF% (-0.005), MTDFY (-0.68 g),MTDSNF% (b=-0.0008) and MTDSNFY (-2.25 g) per unit rise in THI.

Aim: The aim of the present investigation was to optimize the age at first use (AAFU) of semen of Murrah breeding bulls, which will help in early selection of bulls under progeny testing program for improving the reproductive performance in the herd. Materials and Methods: The data on AAFU, conception rate based on first A.I. (CRFAI), overall conception rate (OCR), and birth weight (B.WT) of 57 Murrah bulls during 1993-2014 at NDRI center pertaining to 14 sets of Network Project on Buffalo Improvement at ICAR-National Dairy Research Institute, Karnal, Haryana, India were adjusted for significant environmental influences and subsequently analyzed. Simple and multiple regression models were used for prediction of CRFAI and OCR of Murrah breeding bulls. Comparative evaluation of three developed models (I-III) showed that Model III, having AAFU and B.WT, fulfill the accuracy of model as revealed by high coefficient of determination, low mean sum of squares due to error, low conceptual predictive value, and low Bayesian information criterion. Results: The results revealed that the average predicted CRFAI was highest (39.95%) at 4.5 years of age at first A.I/use. Similarly, average predicted OCR was highest (41.05%) at 4.5 years of age at first A.I/use of Murrah bulls. Conclusion: In organized herd under progeny testing program, Murrah bulls should be used at young age, i.e. prior to 3.5 years, which is expected to result in 5.08% better CRFAI and 1.63% better OCR in comparison to Murrah bulls used after 4.5 years of age.

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 (h 2 ) 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

Aim: The aim was to estimate genetic parameters of weekly test-day (TD) milk yields and first lactation 305-day milk yield (FL305DY) in Murrah buffaloes. Materials and Methods: The data on 39059 weekly test-day milk yield (WTDY) records during first lactation of 961 Murrah buffaloes calved from 1977 to 2012 and sired by 101 bulls maintained in an organized farm at National Dairy Research Institute, Karnal was analyzed to study the effect of genetic and non-genetic factors. Least squares maximum likelihood program was used to estimate genetic and non-genetic parameters affecting WTDY and FL305DY. Heritability was estimated using paternal half-sib correlation method. The genetic and phenotypic correlations among WTDY and 305- day milk yield was calculated from the analysis of variance and covariance among sire groups. Results: The least squares means for FL305DY was found to be 1853.49±15.88 Kg. The least squares means of overall WTDY ranged from 2.44±0.07 kg (TD-43) to 7.95±0.06 kg (TD-8). Effect of period, season and age at first calving groups was found to be highly significant (p

Aim: The present investigation was conducted for evaluating the efficacy of estimating breeding values (BVs) using univariate animal model in comparison to sire model. The various parameters considered for evaluating the efficiency of both linear models were coefficient of determination (R 2 ), coefficient of variation (CV), within sire variance or error variance and spearman's rank correlation estimates. Materials and Methods: Data for the present investigation were spread over a period of 34 years from 1978 to 2012 and consisted of a total of 1988 lactation records of Holstein Friesian crossbred cows sired by 186 crossbred bulls. Results: The percentage of sires having BV (estimated by animal model) more than the average BV for the traits viz. age at first calving (AFC), first service period (FSP), first lactation length (FLL), first calving interval (FCI), first lactation 305 day milk yield (F305MY), first lactation total milk yield (FTMY), milk yield per day of first lactation length (MY/FLL) and milk yield per day of first calving interval (MY/FCI) were 48.05, 49.39, 55.07, 49.21, 50.00, 51.39, 48.67, 50.39%, respectively. The animal model had higher R 2 , lower CV and error variance for most of the fertility and production traits. The spearman's rank correlation estimates indicated similarity of rankings by both the linear models as the animal model is an improvement of sire model. Conclusion: Animal model had a wider range of BVs indicating the greater differentiating ability of the model. Based on R 2 , CV and error variance animal model was found to be superior in comparison to sire model.

Premature disposal of female calves before reaching milch herd and undesirable disposal of lactating cows are the major constraints in achieving larger herd size. During the early lactations, younger cows are supposed to give higher milk yield and undesirable disposal of early calvers, thereby, greatly hampers profitability of a dairy farm. Knowledge of the incidence of disposal along with reasons in various age groups and at various parities is essential to identify which age group or parity is more vulnerable for disposal. Moreover, knowledge of various genetic and non-genetic factors associated with disposal of animals may also be helpful in developing breeding and management strategies to reduce the incidence of disposal. In most of the studies, it was found that major reasons of disposal of dairy cattle were mortality among female calves and involuntary culling among adult lactating cows. Maximum mortality in female calves was observed during earlier ages and pneumonia, gastro-enteritis and debility were major reasons of female calf mortality. Whereas, most of the adult cows left the herd, due to teat and udder and reproductive problems. Moreover, indigenous breeds were found to be more adapted to Indian tropical climatic conditions in comparison to crossbred and exotic cattle breeds.

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.

Present investigation comprehends the study of the effect of genetic and non-genetic factors and estimation of genetic parameters of Karan Fries cattle with respect to production and reproduction traits across all lactations. Data consisted of a total of 5878 lactation records on 1988 cows over a period of 32 years (1981 to 2012), maintained at ICAR-NDRI, Karnal. Overall least-squares means for CFS(days), SP(days), LL(days), CI(days), 305MY(kg), TMY(kg), MY/LL(kg/days), MY/CI(kg/days) and DPR were found to be 78.21±1.59, 115.46±2.14, 326.57±2.60, 403.91±2.54, 3634.78 ± 30.91, 3976.77 ± 41.03, 12.19 ± 0.08, 10.28 ± 0.08 and 0.37 ± 0.80, respectively. Both production and fertility traits were significantly affected by different factors viz. season of calving, period of calving, parity and genetic group. LSANOVA heritability estimates of SP, CI, LL, CFS, DPR, 305MY, TMY, MY/LL, MY/CI were 0.18±0.08, 0.15±0.07, 0.11±0.05, 0.10±0.09, 0.07±0.07, 0.39±0.09, 0.26±0.07, 0.35±0.08 and 0.42±0.10, respectively. Heritability estimates indicated that fertility traits were less affected by additive gene action. Genetic correlation estimates indicated unfavourable positive correlation between fertility and production traits.

The present study was performed to investigate the polymorphisms in the Fibroblast Growth Factor 2 (FGF2) gene and to reveal the association of different genotypes corresponding to gene with Breeding Value (BV) for first lactation milk yield and milk composition traits of Karan Fries (HF crossbred) cattle. The traits were adjusted against the significant effect of non-genetic factors. Blood samples were collected on vacutainer tubes supported with EDTA to prevent blood Clotting and DNA samples were isolated and purified using standard phenol chloroform method. Polymerase chain reactions were performed using specific primers for gene under study. FGF2 gene PCR products were subjected to cut them with specific restriction enzyme: Csp6I. Polymerase Chain Reaction – Restriction Fragment Length Polymorphism (PCR-RFLP) analysis of FGF2 (intron 1) gene revealed three genotypes; GG (171bp), AG (207bp and 171bp,) and AA (207bp). Genotypic frequencies of GG, AG and AA were 0.31, 0.52 and 0.17 whereas the allelic frequencies for G and A allele were 0.57 and 0.43, respectively. Breeding value of GG genotype was highest for ATDMY(kg) and 305MY (kg) (11.21 ± 0.67 and 3172.01 ± 51.33 ) whereas, AA genotype had highest breeding value for ATDFP and LFY (4.39 ± 0.16 and 137.41 ± 5.76). In addition, no significant effect of polymorphism on any of the traits was found. GG genotype was associated with a higher breeding value for 305MY, suggesting its further research in a large population and consequently its use in gene assisted selection for the genetic improvement of milk production.

Acoustic sensing seems to be one of the best methods for monitoring of dairy animals at an organized farm for their better care and management. The main aim of present investigation was to establish the existence of significant differences for various acoustic features of vocal signals uttered from different individuals of a herd of crossbred cows. The mean call duration, mean pitch, 1st formant, periodicity and degree of voice breaks of adult lactating Karan Fries crossbred cattle were observed to be 2.37±0.03s, 191.57±2.40Hz, 790.71±5.54Hz, 97.76% (371.71 periodic pulses out of 380.20 pulses) and 7.64±0.44% respectively. Analysis of bioacoustics features extracted from 300 voice samples of ten adult lactating Karan Fries crossbred cows revealed that differences for amplitudes (minimum, maximum and mean), total energy, mean power, pitch (median, minimum, maximum, range and mean), pitch spreading (84–50, 50–16 and 90–10%), intensities (minimum, maximum and mean ( P P

Data obtained from Holeta Agricultural Research Center in Ethiopia were analyzed to compare the Boran cattle and the crossbreds and estimate genetic and crossbreeding parameters for first lactation traits. First lactation traits studied were first lactation total milk yield (FLMY), first lactation length (FLL), milk yield per day to first lactation (FLDMY), first 305 days milk yield (MY305) and adjusted first lactation 305 days milk yield (AFL305DMY). The effect of genetic group was significant (p 0.05) difference between HF x Bo and HF x HFBo or J x Bo and J x JBo and thus exotic inheritance beyond 50% showed no improvement in first lactation traits. The heritability estimates were medium (0.21+03) for FLL to high (0.39+0.40) for FLDMY. The breed additive difference for HF or Jersey was positive and significant (p 0.05) for Jersey x Boran crosses except FLDMY and AFL305DMY. Crossbreeding improved first lactation traits three to four folds. Thus, crossbreeding with management interventions could be recommended to improve milk production. Key words: Crossbreeding, genetic parameters, milk yield, non-genetic factors.

In the present investigation, bull fertility of Sahiwal breeding bulls has been studied. The study was conducted on records of 43 Sahiwal bulls maintained under 8 sets of Sahiwal breeding project at ICAR- National Dairy Research Institute, Karnal (India). The data on bull fertility of Sahiwal breeding bulls during 27 years (1987-2013) were analysed. The presented study revealed that the average conception rate based on first AI and overall conception rate of Sahiwal breeding bulls were estimated as 45.95% and 46.38 %. Average sire conception rate of Sahiwal breeding bulls range from – 2% to + 3% and – 2% to + 4 % for conception rate based on first AI and overall conception rate. It has been observed that the average conception rate based on first AI was lower as compare to overall conception rate and higher conception rate of Sahiwal breeding bulls is having higher sire conception rate.

Present study was carried out with the aim to determine the effect of genetic and non-genetic factors on milk production efficiency traits and their genetic control. Data on milk production efficiency traits i.e. total milk yield per day of lactation length and total milk yield per day of calving interval in Jersey crossbred animals maintained at organized herd of ICARNational Dairy Research Institute, Eastern Regional Station, Kalyani, Nadia, West Bengal spread over 29 years (1986-2014) were analyzed in the study. The overall least-squares means of total milk yield per day of lactation length and total milk yield per day of calving interval were estimated as 6.97±0.21 and 6.02±0.23 kg/day, respectively. The data was grouped into different sub-classes of season of calving, period of calving, parity and genetic group of animals. The random effect of sire had shown significant (p

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.

A random regression model was applied for the first time for the analysis of test day records and to study the genetic persistency of first lactation milk yield of Indian Murrah buffaloes. Wilmink's Function was chosen to describe the shape of lactation curves. Heritabilities of test day milk yield varied from 0.33 to 0.58 in different test days. The highest heritability was found in the initial test day (5 th day) milk yield. Genetic correlations among test day milk yields were higher in the initial test day milk yield and decreased when the test day interval was increased. The magnitude of genetic correlations between test day and 305 day milk yield varied from 0.25 to 0.99. The genetic persistencies of first lactation milk yield were estimated based on daily breeding values using two methods. P 1 is the genetic persistency estimated as a summation of the deviation of estimated daily breeding value on days to attain peak yield from each day after days to attain peak yield to different lactation days. P 2 is the genetic persistency estimated as the additional genetic yield (gained or lost) from days to attain peak yield to estimated breeding value on different lactation days relative to an average buffalo having the same yield on days to attain peak yield. The mean genetic persistency on 90, 120, 180, 240, 278 and 305 days in milk was estimated as -4.23, -21.67, -101.67, -229.57, -330.06 and -388.64, respectively by P 1 , whereas by P 2 on same days in milk were estimated as -3.96 (-0.32 kg), -23.94 (-0.87 kg), -112.81 (-1.96 kg), -245.83 (-2.81 kg), -350.04 (-3.28 kg) and -407.58 (-3.40 kg) respectively. Higher magnitude of rank correlations indicated that the ranking of buffaloes based on their genetic persistency in both methods were similar for evaluation of genetic persistency of buffaloes. Based on the estimated range of genetic persistency three types of genetic persistency were identified. Genetic correlations among genetic persistency in different days in milk and between genetic persistencies on the same day in milk were very high. The genetic correlations between genetic persistency for different days in milk and estimated breeding value for 305 DIM was increased from 90 DIM to 180 DIM, and highest around 240 DIM which indicates a minimum of 240 days as an optimum first lactation length might be required for genetic evaluation of Indian Murrah buffaloes.

Selection for genetically superior Murrah buffaloes under Network Project on Buffalo Improvement, India, is presently based on milk yield, and it was observed that even in the absence of any direct selection pressure applied on fertility, there has been a downward trend in fertility associated with the selection for milk yield. The aim of the study was to develop selection indices which include fertility besides milk yield in Murrah buffaloes. Data pertaining to 1,224 lactation records spread over a period of 19 years were recorded and analyzed in the study. The negative association of pregnancy rate (fertility) with a 305-day milk yield (−0.08 ± 0.04) and wet average (−0.12 ± 0.02) indicated the importance of incorporating fertility trait in the construction of selection index. Four types of selection indices were constructed and evaluated. Two indices were developed using expected producing ability 305-days milk yield (EPAMY) with 6.5 and 4 % fat in milk along with expected fertilizing ability (EFA). The other two indices developed consist of expected producing ability wet average (EPA WA) and EFA. The index involving (EPA WA and EFA) was found to be a more effective selection criterion in our herd, as the accuracy of index was more (0.61), in comparison to the index involving EPA MY and EFA. The robustness of selection index was assessed by increasing the relative economic values of included traits by 25 and 50 %, and accuracy of the index remains almost stable without much change. The developed selection strategy involving EPA WA and EFA should be considered for the genetic evaluation of Murrah buffaloes, as it has a potential for maximizing the lifetime reproduction and production performances of the breed.

The present investigation was carried out using data of first lactation bimonthly (BTDY) test day milk yields and 305-day milk yield records of 1345 Karan Fries cows sired by 84 bulls from 1984-2006 maintained at NDRI, Karnal. The test day milk yields recorded from 6th to 305th day at bimonthly intervals were used to predict 305 day milk. Based on simple linear regression analysis with only one independent variable, the regression coefficients showed a consistently increasing trend up to BTDY-3 and thereafter a consistently declining trend up to BTDY-7 test day milk yield was noticed. The accuracy of prediction (R2) of 305-day milk yield based on individual bimonthly test day milk yields varied between 19% (BTDY-1) and 59% (BTDY-4). However, slightly higher estimates of accuracy of prediction in the middle portion of lactation in bimonthly test day milk yields were observed. The absolute error, percent error and error variance showed continuously declining trend from BTDY-1 to BTDY-3 but then increasing trend from BTDY-3 to BTDY-6. Based on fitting of stepwise multiple regressions, the regression equation with 3 variables viz. BTDY-2, BTDY-3 and BTDY-5 was considered more appropriate for prediction of first lactation 305-day milk yield with 83 % accuracy and 7.54 per cent error of prediction in 305-day milk yield.