Factors affecting Breeding Efficiency in Cattle and Buffaloes

Introduction

Regular breeding is an important consideration in the economics of cattle production. A calf per year is the usual goal which is possible only by increasing the reproductive efficiency of the animals. Therefore, for successful reproduction to occur it must comply with the ability of males and females to mate, conceive, nourish and deliver viable young ones. The   reproductive efficiency/ Breeding efficiency is controlled both by genetic and non-genetic factors. Climate, nutrition and management of animals are the non genetic factors. The reproductive efficiency varies between different species and breeds but also among animals within the same breed. Even with the best feeding and management animals cannot perform beyond the genetic limit of an animal. Therefore sound breeding programmes are necessary to bring about total improvement in animals. 

Key factors for sound Breeding Efficiency

• Age at first calving: The animals selected must not be too mature or too young and selection for optimum body weight i.e., 55% of mature weight is necessary. Therefore, when age at first service is 14-15 mts, the age at first calving becomes 22.5 to 23.5 months for maximum lifetime profit being.
• Calving interval: Rebreeding after calving depends upon the involution and uterine health of the cow. Extension of inter-calving period from 12 to 14 months or more results into substantial reduction financial return over feeding costs as there will be loss in milk, calves produced per cow etc. Therefore, there will be considerable financial loss if the calving interval extends beyond 365 days in cows and 395 days in buffaloes.
• Inter service interval or interbreeding interval: It is the number of days between services. Inter-service intervals of more than 40 days is common. To shorten it heat detection three weeks after insemination is useful.
• Period of the standing heat: This depends on the efficiency of estrus detection in all cows. But, cow fertility depends upon a number of factors, including the semen quality, correct handling of semen straws, AI-breeding technique and timing of insemination.
• Detection of estrus: For successful fertilization correct estrus detection is essential. Approximately 50% of the estrous periods go undetected on the average dairy farm.
• Proper timing of insemination: Once Ovulation has occurred it is estimated that the viable life of the egg is less than 12 hrs, unless it becomes fertilized as Sperm require about 6 to 10 h to reach the lower portion of the oviduct. Therefore the proper timing of insemination is to inseminate cows at 6 hrs after estrus (standing heat) so that adequate numbers of motile sperm are present in the oviduct.
• Handling of semen straws while AI:. To maintain maximum fertilization rates, shaking of the straw while thawing at at 37°C for at least 30 second. Once thawed, inseminate immediately so as to prevent from cold or heat shock.
• Embryonic losses: Early embryonic loss is critical during 15 or 16 days when the embryo is developed sufficiently to overcome uterine secretion of PGF2α. Additional late embryonic losses can occur during the period of 25 to 40 days after insemination due to failure of attachment to the uterine wall
• Fertility and season : Hot season and high humidity decrease fertility of a cow due to reduction in appetite. Heat stress reduces blood estradiol concentrations, progesterone levels, follicular activity and ovulation. Provision of cooling systems may have a beneficial effect on fertility but the best time of fertility achieved in winter months.
• Dry period: Dry period is a critical component of a dairy cows. Where duration of gestation cannot be shortened, but significantly affect the health or viability of the newborn calves. Nutrients required during this period include the maintenance for the cow plus that required by the developing foetus. Usually 50 days is ideal for ensuing lactation. 

Conclusion

The success of any dairy enterprise depends upon the level of milk production that is directly dependent on the reproduction of animals. Breeding efficiency is controlled by the interplay of genetic and non genetic factors which often decreases due to poor management. Many key areas for improving fertility of animals include selection, control of infectious disease, nutritional management, reproductive management such as oestrous synchronization, ovulation and improving male fertility etc.

Content contributors :

• Saroj Rai, ICAR- National Dairy Research Institute, Eastern Regional Station, Kalyani
• Rani Alex -ICAR- National Dairy Research Institute, Karnal. Haryana