Heifers

Heifer is a young female cow before she has had her first calf.

Heifers should be selected on the basis of the potential of the sire and milk production of the dam.

The heifers should have proper growth, good health and be free from genetic abnormalities.

Heifers, which have conceived within 24 months of age alone, may be retained.

Cows

Most important economic trait to be looked into, while selecting a cow is 'milk production'. The present average daily milk production of the cross breed cows is around 5.5 liters. For economic milk production a cow producing not less than 2500 kg milk in 305 days lactation period is desirable. In general, selecting a newly calved cow yielding ten liters per day may have 2000-2500 kg lactation yield and cow yielding 15 liters per day initially may have a lactation yield of 3000 kg. A peak yield of at least 12 kg milk per day can be used as a criterion for this. Age at first calving should be less than 3 years. The interval between two successive calving should be 12 to 15 months. The cow should not have any physical deformity and should possess dairy conformation like well developed udder, prominent milk vein, squarely placed teats, ease in milking and good temperament. Old and unproductive cows are to be replaced by young cows. The calves reared in the farm itself are usually used for replacement. Normally, 20 percent of the stock has to be replaced each year. When calves are insufficient or when the general performance of the herd is poor, cows from outside can be purchased and added to the herd.

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Bulls

Bulls contribute 50 percent of the inheritance to the next generation. Most of the genetic improvement in a population comes through proper bull selection. It is not very practicable to have intense selection of the females for breeding i.e., almost all the heifers will have to be reared and used for breeding in a situation where age at first calving and calving interval are not optimum. Hence most care is to be given for bull selection. To achieve the goal of average 305 days milk yield of 2500 kg/lactation from the present 1600 kg for crossbreds in Kerala, the bulls used should be proven bulls or of high pedigree. The young bulls used for breeding should be from dams with lactation milk production not less than 4500 kg and bulls with higher sire index. If 1000 cows with this production performance are available in the State, this bull dam selection becomes feasible. Other economic traits like milk fat and SNF, age at first calving, calving ease, incidence of diseases etc., should be included in evaluation.

The farmers should be aware of the quality of bull used for breeding and all Artificial Insemination centres/bull stations should display the details of breeding value of the bulls used. Breeding value is generally expressed as a deviation from the population average. It is to be borne in mind that pedigree selection is the most important of all kinds of selection. Progeny testing is the most accurate method and as a rule bulls for progeny testing are selected based on the pedigree. Selection should be continuous and applied in all generations. Any slack in selection will result not only in the stoppage of genetic improvement but also in creating negative trends.

I. Introduction

Reproduction is an important consideration in the economics of cattle production. In the absence of regular breeding and calving at the appropriate time cattle rearing will not be profitable. A healthy calf each year is the usual goal. This is possible only by increasing the reproductive efficiency of the animals.

Successful reproduction encompasses the ability to mate, the capacity to conceive and to nourish the embryo and deliver the viable young ones at the end of a normal gestation period. In fact, interruption in this chain of events leads to failure of the cow either to conceive or the embryo to die or to have a premature delivery of the foetus.

The reproductive efficiency is a complex phenomenon controlled by both genetic and non-genetic factors, the non- genetic factors being climate, nutrition, and level of management. The reproductive efficiency varies not only between species and breeds but also among the animals within the Same breed. Even the best feeding and management can not coax performance beyond the genetic limit of an inferior animal. Improving the genetic merits of livestock populations is important at all levels of management. A sound breeding programme is a necessary part of the total animal production system. It is absolutely imperative to improve the productive capacity and physical appearance of the animal population.