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ThesisItem Open Access Effect of different levels of dietary calcium on performance and mineral availability in crossbred dairy cattle(Department of Animal Nutrition, College of Veterinary and Animal Sciences, Mannuthy, 2006) Smitha Wilson; KAU; Syam Mohan, K MAn investigation spread over a period of four months was undertaken in crossbred dairy cattle to assess the effect of different levels of dietary calcium on the performance and mineral availability in cross bred dairy cattle. Twelve healthy crossbred cows in the last month of pregnancy having an average peak yield of minimum eight litres per day in their previous lactation were selected. They were divided into two groups of six each as uniformly as possible with regard to age and milk yield and allotted to two dietary treatments viz., T1 (control ration) where in the compounded cattle feed contained 0.5 per cent calcium as per IS (1992) standards and T2 (experimental ration) where in compounded cattle feed contained 1.0 per cent calcium. Paddy straw was the sole roughage source in both the rations. All the experimental animals were fed as per ICAR (1999) standards except for dietary Ca and maintained individually on their respective dietary regime from the last month of calving to three months of lactation. Average dry matter intake, fortnightly body weight, milk yield, milk fat percentage, total solids, solids not fat, serum minerals, mineral content of milk, balance of Ca, P, Mg and Zn and incidence of metabolic disorders were the criteria employed for evaluation. Average body weights and dry matter intake of animals revealed no significant difference for both the groups during all the fortnights studied. Highest dry matter intake for the group I was recorded during the third fortnight and for group II in the second and third fortnight. Average daily milk yield, fat percent, total solids and solids not fat per cent in milk in all the six fortnights did not differ significantly between the groups. The average mineral concentration in milk collected after calving, and at the first, second and third month of lactation for the animals in group II and I did not differ significantly. The mineral content in serum and milk in both groups were within the normal range reported for the species. Results with respect to balance of P and Zn did not differ significantly whereas that for Ca, and Mg differed significantly (P<0.05) between the two groups. Higher retention values were recorded in group II for Ca and group I for Mg. The average retention percent of Ca and Mg differed significantly (P<0.05) the higher values recorded in group I for Mg and in group II for Ca. There was no incidence of metabolic disorders like hypocalcaemia, hypomagnesaemia and ketosis in both groups of animals. An overall critical evaluation of the results obtained in the present study helps to infer that different levels of calcium followed in the present study has a major effect on improving the Ca balance of early lactating cows. The results suggest that levels of Ca in compounded cattle feed at one per cent is better than 0.5 per cent to avoid negative balance of calcium during early lactation when paddy straw is the sole roughage source. The study also indicates that with high levels of dietary Ca there is a need for Mg supplementation to avoid negative balance arising due to interaction of the two elements.ThesisItem Open Access Effect of restricted milk feeding on growth performance in cross bred calves(Department of Animal Nutrition, College of Veterinary and Animal Sciences, Mannuthy, 2006) Jasmine Rani, K; KAU; Gangadevi, PAn experiment was conducted with eighteen cross bred calves below one week of age for 150 days to assess the effect of restricted milk feeding on growth performance in cross bred calves. Calves were divided into three groups (group I, II and III) as uniformly as possible. Calf starter prepared as per BIS specification formed the experimental diet. Calves of group I, II and III were fed with whole milk up to twelve, eight and four weeks of age respectively at the rate of 1/10th of their body weight from birth to six weeks of age, 1/15th of the body weight from seven to eight weeks and 1/20th of body weight from nine to twelve weeks of age. Good quality green grass was fed ad libitum. Body weight gain, daily dry matter consumption, feed conversion efficiency, cost per kg gain, digestibility of nutrients and haematological parameters such as haemoglobin, plasma protein, plasma glucose, serum calcium and serum phosphorus were the criteria employed for the evaluation. Average daily gain and total weight gain, respectively were 300g and 45 kg for group I, 307.78g and 46.17kg for group II, 321.67g and 48.25kg for group III and the values were not significantly different (P>0.05). Average daily dry matter intake (kg/day) was 1.19, 1.10 and 1.31 kg respectively for group I, II and III and there was no significant difference (P > 0.05) among the groups. Feed to gain ratio for group I, II and III was 4.14, 3.59 and 4.23 respectively and was not significantly different (P>0.05) among the groups. The digestibility coefficient of nutrients observed was 77.74, 74.14, and 73.75 for dry matter, 81.51, 79.66, and 79.15 for crude protein, 84.41, 82.83, and 82.80 for ether extract 84.55, 81.97, and 81.20 for NFE, 65.08, 58.92, and 58.19 for NDF and 54.38, 46.97 and 45.64 for ADF for group I, II and III respectively. There was no significant difference (P>0.05) between the groups in the digestibility of any of the nutrients studied. The haematological parameters such as haemoglobin, plasma protein, serum calcium and serum phosphorus did not show any significant difference (P >0.05) among the groups. A significant reduction (P<0.01) in plasma glucose values was observed at second, third and fourth month in early weaned groups than in control group. The cost per kg gain was Rs. 88.14, 65.62 and 53.95 for group I, II and III, respectively. There was a saving of Rs.22.52 and Rs.34.19 for group II and III, respectively compared to the control group. On a critical evaluation of results obtained in the present study, it was revealed that calves fed milk up to 28 days registered similar body weight gain, dry matter consumption, feed efficiency, digestibility of nutrients and haematological parameters at least cost, compared to the late weaned calves. On summarizing the overall results of the study, it could be inferred that cross bred calves can be successfully weaned from milk as early as four weeks of age with out any adverse effect on their growth performance as they had superior economical efficiency and similar biological efficiency to calves received milk up to eight or twelve weeks of age.