Growth and reproductive performance of crossbred heifers in selected areas
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Date
1998
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Department of Animal Reproduction, College of Veterinary and Animal Sciences, Mannuthy
Abstract
Growth and reproductive status of crossbred heifers under field condition were assessed and the role of calcium, phosphorus, copper, zinc and manganese with reproductive performance was evaluated with the aim of evolving suitable corrective measures in cases of those with impaired reproductive performance due to subnormal serum mineral status.
One hundred and twelve heifers were subjected to repeated gynaecoclinical examination. It was observed that there were 36.6 per cent true anoestrum, 19.6 per cent under developed genitalia, 29.5 per cent normally cycling, 9.8 per cent repeat breeders, 3.6 per cent suboestrum and 0.9 per cent bilateral ovarian hypoplasia.
From the above heifers 89 were randomly selected and classified based on the breeding history and repeated gynaecological examination as 15 normally cycling (control), 41 true anoestrous heifers, 22 under developedgenitalia and 11 repeat breeders. The daily weight gain obtained was 55.05 ± 4.2 g, 32.26 ± 2.49 g, 27.33 ± 3.4 g and 24.1 ± 4.8 g. The above result gave significant difference in weight gain between control animals and other groups. The growth rate of heifers might have influenced the normal reproductive performance.
Serum samples drawn from 89 heifers were analysed for calcium, inorganic phosphorus and trace elements namely copper, zinc and manganese. Serum calcium and phosphorus were estimated by employing spectronic-20, i&hile trace elements were estimated through atomic absorption spectrophotometer. The serum calcium level obtained was 11.1 ± 0.31 mg%, 10.74 ± 0.13 mg%, 10.8 ± 0.2 mg% and 10.8 ± 0.42 mg% in normally cycling, true anoestrous, under developed genitalia and repeat * breeding heifers respectively. The serum levels of all the four groups were well within the normal range and no significant variation among the groups. Hence the influence of calcium on reproduction could not be established.
The serum inorganic phosphorus was 4.87 ± 0.13 mg% in normally cycling heifers (control) as against 3.83 ± 0.09 mg% for true anoestrous heifers, 3.52 ± 0.1 mg% for underdeveloped genitalia and 4.7 ± 0.15 mg% for repeat breeders. The level was significantly lower (<0.05) in true anoestrous and underdeveloped genitalia compared to control group. It can be summarised that hypophosphataemia might be one of the cause for true anoestrum and under developed genitalia.
Among the trace elements estimated the serum level of copper only was found to be significantly varying among normally cycling, true anoestrous and heifers with under developed genitalia. The serum copper in control group heifers registered a value of 1,26 ± 0.07 ppm which was significantly higher (P<0.01) than those recorded for true anoestrous heifers (O’. 9 ± 0.04 ppm) and heifers with under developed genitalia (0.71 ± 0.05), ajhile no statistical significant variation obtained between serum value of repeat breeders (1.27 ± 0.08 ppm) and the control group. It is therefore reasonable to assume that hypocupraemia as evidenced by lower serum value might have contributed to true anoestrum and under developed genitalia condition and not with that of repeat breeding condition.
The serum zinc and manganese levels of control group were 1.71 ± 0.05 ppm and 0.04 ± 0.002 ppm respectively. The corresponding values for the true anoestrum heifers were 1.61 ± 0.03 ppm and 0.04 ± 0.002 ppm and for heifers with under developed genitalia group were 1.6 ± 0.05 ppm and 0.04 ± 0.002 ppm respectively. These values did not vary significantly from those of control group. The corresponding values for repeat breeders were recorded to be 1.73 ± 0.06 ppm and 0.04 ± 0.002 ppm which did not differ: significantly from the values obtained for control group.
The result of supplementation with dicalcium phosphate and copper sulphate to the respective mineral deficient heifers with true anoestrum and under developed genitalia showed that the mineral supplementation could induce oestrum.
The serum mineral status comparison at different level of feeding showed significant difference (P<0.05) in the serum phosphorus level as well as copper level of moderate plane group with that of low and poor plane groups. Hence the effect of plane of nutrition on serum mineral status could be established in case of serum phosphorus and copper.
The soil level of calcium, phosphorus, copper, zinc and manganese found to be well within the normal range. The level of exchangeable calcium and available phosphorus were ranged 0.11-0.12 per cent and 0.05-0.06 per cent respectively. The available copper, zinc and manganese levels obtained were ranged 4.43-4.5 ppm, 5.3-5.44 ppm and 96.34-99.7 ppm respectively. The result showed that the soil mineral content did not influence: the serum mineral status
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