Dr. V. N. KhuneAMIT SHEKHAR2024-09-192024-09-192017https://krishikosh.egranth.ac.in/handle/1/5810214594The study was conducted on 26 purebred Sahiwal cows during early lactation period (calving to 98 days postpartum) in two farms i.e., the CBF and BMEF with the objectives to observe the variations in body condition score, milk production, peak yield, milk composition viz., milk fat, milk protein, lactose and milk SNF and their interrelationships in Sahiwal cows during early lactation period. The experiment was conducted in cows which were calved during January 2017 to April 2017. The data were classified on the basis of farms (CBF and BMEF), BCS at calving (lower, medium and higher groups) and postpartum changes in BCS (no change, moderate loss and high loss groups). BCS was measured using the scoring system of 1 to 5 point scale with quarter point increment at fortnightly intervals during the early lactation period. The Sahiwal cows of CBF herd calved at an average BCS of 3.64±0.05, non significantly higher than that of the BMEF herd (3.45±0.07). The overall postpartum mean BCS of cows of CBF (3.28±0.04) differed significantly from that of BMEF (3.09±0.08). The overall mean milk fat concentration of Sahiwal cows of CBF herd (3.32±0.03%) was non significantly higher than that of BMEF herd (3.29±0.02%). The overall mean milk fat % is significantly higher (P<0.01) in Sahiwal cows of higher BCS at calving group (3.43±0.02%) than those of lower (3.27±0.01%) and medium BCS at calving groups (3.26±0.01%). While, the overall mean milk fat concentration for no change, moderate loss and high loss groups based on postpartum change were 3.26±0.05%, 3.26±0.05% and 3.27±0.07%, respectively. The overall mean milk protein concentration in BMEF cows (3.82±0.15%) was non significantly higher than those of CBF cows (3.78±0.04%). The overall mean milk protein concentrations in the cows having lower (3.89±0.12%) and medium (3.91±0.02%) BCS at calving were significantly (P<0.01) higher than that observed in cows of higher BCS at calving (3.63±0.07%). The overall mean milk lactose % of BMEF cows (4.70±0.05%) were significantly (P<0.01) higher than those of CBF cows (4.51±0.07%). Significantly (P<0.05) lesser overall postpartum mean lactose percentage was observed in cows of higher BCS at calving group (4.47±0.07%) than those of lower (4.68±0.04%) and medium (4.66±0.04%) BCS at calving groups. Significantly (P<0.01) lesser overall mean lactose percentage was observed in Sahiwal cows of high loss group (4.39±0.05%) than those of medium (4.59±0.05%) group which further was significantly lower than cows of no change (4.78±0.04%) group. The overall mean milk SNF concentrations of Sahiwal cows calved at lower (8.80±0.03%) and higher (8.74±0.02%) BCS at calving were significant than cows calved at medium BCS group (8.66±0.03%). The mean milk SNF concentrations in Sahiwal cows of no change (8.74±0.02%) and high loss (8.72±0.03%) groups were significantly higher than that of the moderate loss group (8.56±0.03%). In most of the groups, significant reduction in the mean milk SNF concentration from calving to at 98 days post-partum was observed. The Sahiwal cows having higher BCS at calving had given significantly (P<0.01) higher amount of milk (683.26±19.62 kg) during early lactation period than those of lower and medium range of BCS at calving i.e. 547.87±19.35 kg and 541.58±18.85 kg, respectively. Similarly the peak milk yield in cows of higher BCS at calving group (7.95±0.26 kg) was significantly higher than those of lower and medium range of BCS at calving i.e. 6.75±0.25 kg and 6.75±0.22 kg, respectively. The Sahiwal cows of higher BCS at calving had yielded significantly higher total milk fat (22.43±0.59 kg), average milk fat per kg of milk (34.38±0.25 g), total protein (24.73±0.75 kg), average milk protein per kg of milk (36.41±0.53 g), total lactose (30.28±0.73 kg) and total milk SNF (58.97±1.86 kg) than the medium and lower BCS at calving group of cows. This might be due to that the cows of higher BCS at calving had calved at significantly higher BCS at calving than the medium and lower group cows. However, the average lactose per kg of milk and average milk SNF per kg of milk of higher BCS at calving group cows were significantly lesser than those of lower group i.e. 46.87±0.51 g and 88.13±0.31 g, respectively. The Sahiwal cows having moderate and high unit loss in BCS from calving had given significantly (P<0.01) higher amount of milk (613.83±26.97 kg and 677.02±29.65 kg, respectively) during early lactation period than those of no change group (530.22±15.14 kg). Similarly the mean BCS at calving in the Sahiwal cows of moderate (3.58±0.07) and high unit loss (3.80±0.05) groups were significantly higher than the BCS at calving of cows of no change group (3.38±0.06). Similarly, the peak milk yield in cows of having moderate and high unit loss in postpartum BCS groups (7.41±0.28 kg and 7.90±0.36 kg, respectively) were significantly higher than cows of no change group (6.55±0.19 kg). Similar to the significant trend obtained for early milk production the Sahiwal cows of postpartum moderate and high loss in BCS groups had yielded significantly higher total milk fat (20.00±0.91 kg and 22.11±0.81 kg), than the cows of no change group (17.30±0.51 kg). However, non significant differences in milk fat grams per kg of milk were noticed in these groups. Average total milk protein of Sahiwal cows of postpartum moderate loss and high loss in BCS groups (23.24±0.83 kg and 24.33±1.17 kg) was significantly higher than that of no change group (20.50±0.62 kg). However, the cows of no change and moderate loss groups had given significantly higher amount of milk protein per unit of milk (39.00±0.54 g and 38.70±0.90 g) than those of high loss groups (36.53±0.70 g). Associations between BCS at different periodical intervals of early lactation yield, peak milk yield, days to attain peak yield and milk fat, milk protein, lactose, SNF parameters of all cows in all the classifications have been worked out to understand the role of each of them in modulating the profiles during early lactation period in Sahiwal cows.EnglishThesis