Introduction

The lower survivability as well as higher disposal (mortality and culling) of calves will result into poor replacement of breeding stock and adversely affect the improvement of animals and this problem can be shot out by genetic improvement as well as the improvement in management practices. As larger herd size facilitates in more intense selection and gives freedom for voluntary culling to the breeder so this is the Primary requirement for genetic improvement of the breed. The herd size can be increased by reducing the selection intensity and improving health status and survivability. Disposal (comprising mortality and culling) of animals is a major constraint in achieving the goal. The knowledge of mortality rate, its causes and factors affecting it at various ages are very essential in a given herd for producing replacement to maintain proper herd structure. In every farm some calves leave the herd due to death and such loss of calves not only reduces the economic soundness but also limits the genetic progress by providing fewer replacements. Therefore, getting more number of female calves by increasing the fertility status and reducing the involuntary disposal at prenatal as well as postnatal stages are the best way to increase herd size for genetic improvement and profitable dairy enterprise. The successful calf rearing is the key to success of dairy farm enterprise because these young calves will be the future replacement stock of dairy farm. Therefore, calf management should be scientific, proper and appropriate.

Materials and Methods

The present study was conducted on crossbred (Karan Fries) cows and their calves belonging to Livestock Research Centre, ICAR-National Dairy Research Institute, Karnal, which comprised of 999 cows and 4744 calving in Karan Fries herd of the farm over the period of 20 years from 1994 to 2013. The 20 years data were classified in 4 periods i.e. P1, P2, P3 and P4, each comprising of 5 years. The year of birth/calving was divided into 4 seasons, according to climatic condition of the farm as winter (December to March), summer (April to June), rainy (July to September) and autumn (October to November). The parities were classified in 6 groups (I, II, III, IV, V and VI and above) and birth weights of calves divided in 4 groups (≤22; 23 to 26; 27 to 30 and ≥31 Kg). The data were used to calculate various components of disposal pattern like abnormal birth, mortality and culling in female calves and heifers up to age at first calving (AFC) and replacement rate for female calve. The average values of abnormal birth or prenatal calf losses were considered in terms of abortion, still birth and premature births.

Abnormal Birth

It is percentage of prenatal calf mortality due to abortion, premature birth and still birth.

Mortality up to Age at First Calving (AFC)

It is percentage of female calves died out of total female live births up to AFC.

Culling up to age at first calving (AFC)

It is percentage of female calves culled out of total live female births up to AFC.

Disposal to Age at First Calving (AFC)

It is incidence of disposal of female calves up to age at first calving.

Replacement Rate on Total Female Calf Born Basis

It is percentage of female calves reaching the milking herd over the total number of female calves born.

Replacement Rate on Total Calf Born Basis

It is percentage of female calves reaching the milking herd over the total (male and female) calves born.

Descriptive statistics were carried out for analysis of disposal pattern and replacement rate. The percentage of animals disposed from the herd due to mortality and culling was calculated by proportion. The analysis of influence of various factors on disposal pattern and replacement rate was carried out by Chi- square method (Snedecor and Cochren, 1994) using the SPSS software.

χ2 = Σ[(O – E)2 / E]

Where

O = Observed frequencies

E = Expected frequencies

Expected frequencies were calculated as follows-

E_ij = (R_i.)(C._j) / GT

Where

E_ij = Expected frequency belongs to i^th row and j^th column

R_i. = i^th row total

C._j = j^th column total

GT = Grand Total

Results and Discussion

The incidence of abnormal birth in Karan Fries was found to be 11.70% in 4744 calving (Table 1). Values similar to present findings were reported by Atrey et al. (2005) in Frieswal while lower estimates than our findings were reported by Shahi and Kumar (2006) in J X SW cross; Singh (2001), Mukherjee et al. (1993) for KF; Mehrotra and Dey (1998) for HF X Haryana cross and Pandey et al. (2012) for cross-bred. Higher estimate was reported by Goshu and Singh (2013) for HF cattle. There was non-significant effect of period of birth on abnormal birth while season of birth and parity shown the significant (P≤0.01) effect (Table 1). There was higher prenatal mortality in rainy season (13.45%) and lower in winter season (9.65%) and it might be due to inclement weather and stressful condition during rainy season as the animals were at their advance pregnancy stage which is most vulnerable and critical stage. Pandey et al. (2012) reported that the incidence of abortion significantly (P≤0.01) affected by season and period of calving as less among cows which calved during summer (6.34%) than those calved during rainy season (7.87%). Atrey et al. (2005) observed that season and period of birth and parity of dam had significant effect on abnormal birth.

The average incidence of disposal, mortality, culling and replacement rate on female calves and total calves basis upto age at first calving were found as 40.38, 33.21, 7.16, 59.61 and 29.00%, respectively (Table 1). Almost similar findings observed by Hossain et al. (2014) while lower estimates reported by Atrey et al. (2005) in Frieswal, Shahi and Kumar (2006) in J X SW cross, Singh (2001), Singh (1995), for KF and higher estimate by Pandey et al. (2012) for cross-bred. It was found that period of birth shown the significant effect (P≤0.01) on the disposal, mortality, culling of calves and its replacement rate upto age at first calving.

Table 1: Incidence of Disposal, Mortality, Culling and Replacement Rate (%) In Karan Fries from Birth to AFC

Figures in parentheses are number of observations; *= Significant at P≤ 0.05; ** = Significant at P≤ 0.01; df =degree of freedom RRFC = Replacement rate on female calf basis; RRTC = Replacement rate on total calf basis; AFC= Age at first calving

Disposal and mortality were higher and replacement rate was lower during fourth period while culling was higher during first period (Table 1). The significant effect (P≤0.05) of birth weight of calf was observed on the disposal, mortality and replacement rate of calves. It was observed that the calves born with lower birth weight shown the higher disposal and mortality, while lower replacement rate. It might be due to higher risk of their immune deficiency and more vulnerable to disease and poor growth performance which resulted in their higher disposal. Season of birth has shown no significant effect on these parameters except culling as it was higher in calves, which was born during rainy season. Mortality and disposal were higher in calves born during summer season while lower in winter season. Effect of parity of dam was non-significant. Goshu and Singh (2013) reported that the season effects on mortality rates of females from birth to age at first calving were found to be non-significant while year differences in mortality rates of the Holstein Friesian heifers were found to be highly significant (P ≤0.01). Panmei et al. (2015) reported that in male Karan Fries calve, effect of periods of birth were found to be statistically significant (p<0.01) for overall disposal rate which may be due to different managemental practices over the years.

Table 2: Reasons of mortality in Karan Fries from birth to AFC

Table 3: Disposal due to culling reasons in female calves’ up to AFC

Various reasons contributing to mortality in female calves and heifer from birth to AFC are presented in Table 2. It revealed that in KF female calves out of total mortality during the study period, highest mortality was due to enteritis & gastroenteritis (24.82%) followed by debility and poor health (17.70%), pneumonia (16.99%), toxaemia & septicaemia (12.70%), and so on (Table 2). The miscellaneous causes of mortality were joint ill, navel ill, dehydration, anoxia, poisoning, snake bite, encephalitis, and hernia. Similarly Singh and Mishra (1989) for HF X Haryana crosses and Somvanshi (1995) for crossbred observed higher incidence of enteritis as a cause of mortality in female calves’ upto age at first calving. Nehra (2011) also reported almost similar finding in KF calves. Singh and Gurnani (2004) also reported that the Karan Swiss females, in their early life died mostly due to pneumonia and gastrointestinal disorders and culled due to poor growth and health problems. Disposal due to culling reasons in female calves’ up to AFC is presented in Table 3. It revealed that the maximum culling was due to reproductive problems (47.26%) followed by poor health and debility (41.09%), miscellaneous (8.21%) and lameness and physical deformity (3.42%). Miscellaneous causes were off bred, transfer and skin infection. Kulkarni and Sethi (1990) in Karan Swiss also reported that reproductive disorder was the major cause of culling of female calves and heifer whereas Jadhav (1990) in HF X Sahiwal crossbreds reported higher incidence of poor growth as a major reason culling.

Conclusions

The present findings concluded that the calves born with lower birth weight were more prone to involuntary disposal i.e. mortality and culling. There was also a significant (P≤0.01) effect of period of birth and birth weight of calves on mortality, disposal and replacement rate. Therefore intensive feeding and health care management is basic need for calves born with lower birth weight which will minimize the involuntary disposal and improve the replacement rate by increasing the number of females reach to milch herd.

References

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