Summary The objective of the current study was to estimate the genetic parameters for ewe productivity traits of Harnali sheep by examining non-genetic effects. The data records of 440 animals born to 85 sires and 259 dams were collected with respect to various traits such as litter size at birth (LSB), litter weight at birth (LWB), litter size at weaning (LSW), litter weight at weaning (LWW) and age at first lambing (AFL) for the period of 2001 to 2020. Genetic parameters were estimated by fitting a series of animal models using an average information restricted maximum likelihood (REML) algorithm in WOMBAT software. Least-squares analysis revealed significant (P < 0.05) influences of period of lambing, age and weight of ewe at lambing on the studied traits. These results indicated that heavier ewes had significantly higher (P < 0.05) values of litter weight traits than their counterparts. On the basis of likelihood ratio test, the estimates of direct heritability under best model for AFL, LSB, LWB, LSW and LWW were 0.06, 0.18, 0.09, 0.07 and 0.16, respectively. Maternal permanent environment effect made a significant contribution to the LSB trait (0.20). The genetic correlation between litter size and LWW was negative, while the remaining correlations were positive. The present results suggest that selection based on ewe productivity traits will result in low genetic progress and therefore the management role is more important for better gains.

Lamb survival is a critical aspect in the sheep industry as it increases the chances of economic gain in the flock. The objective of the current study was to assess the incidence of lamb mortality in Harnali sheep and to estimate maternal and additive genetic effects of lamb survival using the data of 2057 lambs born to 134 sires and 623 dams for the period of 20 years (2001–2020). The genetic evaluation was carried out using threshold animal models comprising direct and maternal effects using THRGIBBS1F90 and POSTGIBBSF90 programs. Cumulative mortality (95% CI (confidence interval)) for the S1 (lambs which died up to weaning age), S2 (lambs which died from birth to 6 months of age) and S3 (lambs which died from birth to 12 months of birth) groups was 8.41 (7.21–9.61), 14.10 (12.59–15.60) and 17.70 (16.05–19.34) %, respectively. The logistic regression analysis revealed significant (p < 0.05) influences of non‐genetic factors and indicated that the female lambs, heavier dam and higher birth weight of lamb were associated with better survival as compared to their counterparts. The estimates of direct additive heritability for S1, S2 and S3 were 0.04 ± 0.01, 0.07 ± 0.03 and 0.11 ± 0.04, respectively. In addition to this, significant influences of the maternal permanent environmental effects were observed for lamb survival up to weaning as well as six months of age. Thus, the present findings suggest that lamb survival could be improved through better management practices but consideration of maternal permanent environmental effects is important for initial survival of the lamb.

Summary The present study was carried out to estimate lamb survival (in days) from birth to weaning under survival analysis using data records from 2057 Harnali lambs born to 134 sires and 623 dams between the period from 2001 to 2020. The weaning age in resourced population was 90 days from birth. The hazard ratio in terms of risk of death up to weaning was determined using Cox proportional hazards model by subjecting some fixed factors such as year of birth, sex of lamb, birth weight (kg), dam’s weight at lambing (kg) and dam’s age at lambing (years). The overall survivability up to weaning among lambs was 91.59% and Kaplan–Meier estimates of mean survival time up to weaning was 85.77 days. Cox proportional hazard modelling revealed that the hazards of death up to weaning was higher in male lambs [1.66, 95% confidence interval (CI): 1.22–2.26] compared with female lambs [hazard ratio (HR) = 1.00]. It was also observed that the hazards of death (HR = 0.91, 95% CI: 0.88–0.94) had decreasing trends over years. For birth weight (kg), hazard rate was 0.34 (95% CI: 0.25–0.46), which indicated that the risk of pre-weaning mortality was lower as birth weight increases. The weight and age of dams at lambing did not influence the survival time of studied population. The present findings indicated that survival time increased in studied lambs over the years and it could be increased more by giving more emphasis on better litter weight and general health aspects at farm level.

Cows' Lactation Milk Yield (LMY) is a crucial factor in animal breeding operations. Investigating the influence of potential environmental factors on lactation milk yield is of paramount importance and in order to identify the various factors influencing lactation milk yield, dairy cattle records were analysed using the regression tree approach. Age, Parity (P), Lactation Length (LL), and Calving Season (CS) were taken into account as explanatory variables while 305-day Milk Yield (MY) as a dependent variable. Decision tree study revealed that Lactation Length, followed by Parity, Age, and Calving Season, had the greatest impact on the 305-d milk output of cross-bred cows. It was evident from nodes (branches) in regression tree, that cows with parities of 1 and 4 (node 11) produced less milk than cows with parities of 2, 3, 5, 6, 7 and 8 (node 10). More milk was produced by cows older than 4.3 years and whose calving seasons were spring and summer (node 40). With the use of the regression tree method, we were able to extract sub-homogenous groups based on the explanatory variables from records of cross-bred cattle and determine the combinations of environmental conditions that produced the maximum 305-d milk yield.

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