• Asian-Australasian Journal of Animal Sciences
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• v.15 no.12
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• pp.1714-1718
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• 2002

Twelve prepubertal Karan Fries heifers (15 months, $167.7{\pm}13.5kg$) were divided into two equal groups. Group 1 was fed as per NRC requirements and group 2 was fed 20% more protein than group 1 heifers. The experimental feeding was continued until the onset of puberty in both the groups. Blood samples were collected at fortnightly intervals and analyzed for amino acids using HPLC. Group 1 and 2 heifers required $178.6{\pm}33.8$ and $152.8{\pm}33.2$ days of experimental feeding to exhibit first estrus resulting in total age at puberty as $639.4{\pm}27.3$ and $618.6{\pm}24.6$ days in the two groups respectively. The concentration of total amino acids averaged 4.40 and 4.89 mmol/l and those of non-essential amino acids (NEAA) was 2.32 and 2.49 mmol/l in groups 1 and 2, respectively. The concentration of plasma essential amino acids i.e. histidine, threonine, valine, methionine, isoleucine, leucine and phenylalanine were higher (p<0.01) in group 2 than group 1. Plasma concentration of large neutral amino acids (LNAA) was significantly higher in group 2 (1.28 mmol/l) than in group 1 (1.12 mmol/l). Increased levels of leucine, isoleucine and valine are implicated in increased follicular growth and development in prepubertal heifers and resulted in a 26 day earlier attainment of puberty by 26 days in an experimental period of six months in group 2 heifers. Increased concentrations of aspartate and tyrosine in group 2 heifers might be associated with the release of GnRH from the hypothalamus influencing LH release from anterior pituitary in such animals. It is therefore evident that increased availability of certain amino acids in heifers fed high protein diet might have led to early onset of puberty.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.4
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• pp.450-455
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• 2010

The study had two objectives, namely, to estimate the andrological disorders leading to disposal of Karan Fries (KF), Sahiwal cattle and Murrah buffalo bulls and to study the effect of various factors (species/breeds, season of birth and period of birth) on male reproductive parameters. Records on occurrence of subfertility problems and disposal pattern of bulls maintained at the National Dairy Research Institute herd were collected for 15 years (1991 to 2005). Percentage of bulls producing freezable semen was less in the crossbred cattle (58.46%) as compared to Sahiwal (81.69%) and Murrah bulls (81.05%). Various subfertility traits like poor libido and unacceptable seminal profile were found to be the significant reasons (p<0.01) for culling of the breeding bulls. Inadequate sex drive was the main contributing factor for bull disposal in Sahiwal (22.55%) and Murrah bulls (15.12%) whereas poor semen quality and freezability were most frequently observed in KF bulls (24.29 and 7.29 percent, respectively). Least squares analyses of different male reproductive parameters showed that species/breeds had significant effect (p<0.05) on all traits except for frozen semen production periods (FSPP). Periods of birth were significantly different (p<0.05) for all traits except for semen volume. Age at first semen collection (AFSC), age at first semen freezing (AFSF) and age at disposal (AD) were highest in Murrah, while frozen semen production period (FSPP) and semen production period (SPP) were highest in KF and lowest in Sahiwal. The age at first semen donation and breeding period could be reduced by introducing the bulls to training at an early age. These results revealed a declining trend in AFSC, AFSF, FSPP, SPP and AD, thereby indicating an improvement in reproductive performance over the years. The age at first semen donation in bovines can be reduced by introducing the young male calves to training at an early age, which could increase the dosage of semen obtained from each male.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.12
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• pp.1742-1748
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• 2006

The experiment was conducted on 264 crossbred Karan-Fries (Holstein Friesian${\times}$Tharparkar) cows, over one year to explore the possibility of using milk urea (MU) concentration and milk protein content to monitor feeding adequacy under farm condition and to investigate the effects of different animal factors and season on MU concentration. Individual noon (1200 to 1300 h) milk samples were collected once in every month and analysed for urea and protein contents. Representative feed samples were also collected on the same day of milk collection and were analysed for CP content. A significant positive association (p<0.01) between MU concentration and milk yield was observed. MU concentrations (mg/dl) were found to be significantly (p<0.01) higher and lower in first lactation (44.8${\pm}$0.7) and in early lactation stage (40.7${\pm}$0.5), respectively. Average MU values were found to be significantly (p<0.01) higher in winter (50.7${\pm}$0.3) and lower in summer (32.9${\pm}$0.6). During the investigation, of the total MU observations, 50.3% were within the range of 30 to 50 mg/dl, 21.4% were <30 mg/dl and only 7.5% were >60 mg/dl. MU concentration was found to be associated significantly (p<0.05) with CP content of forages rather than concentrate. A close positive association (p<0.01) between MU level and daily milk protein (DMP) yield was observed during the investigation. The regression equation, DMP yield (g) = -24.6+33.5 daily milk yield (kg) +0.9 MU (mg/dl) was developed to establish the reference level of DMP yield. The result indicates that the effect of parity and stage of lactation may be ignored while interpreting MU values. However, reference MU values may be standardised separately for high milk yielders as level of milk yield contributes significantly to the variation of MU. The study revealed that the MU values together with DMP yield and milk protein content could be used as a potential non-invasive pointer to monitor feeding adequacy in dairy cows under farm conditions.