ANIMAL HUSBANDRY INFORMATION

CATTLE

Reproduction and Gestation

Reproduction

Puberty: Early onset of puberty is an economic factor in cattle rearing. It differs in different breeds of cattle. On attainment of puberty, the healthy animal will come into oestrum at regular intervals. The interval between two heat periods is called oestrous cycle. Duration of oestrous cycle varies from 18-21 days. Duration of heat or sexual receptivity ranges from 18-25 hours in different breeds.

Onset of puberty

Detection of oestrum in cows can be made from :

•  External manifestation including behavioural signs of oestrum

•  Mucous discharge

•  Turgidity or tone of the uterus

The external manifestations include excitement, loss of appetite, bellowing, reduction in milk yield, licking other animals, mounting other animals, standing still to be mounted, frequent urination, swollen vulva and pink and moist vaginal mucous membrane. The mucous discharge will be ropy, elastic and clear. On rectal palpation, cervix will be relaxed; uterus will have good tone and will be turgid.

Insemination should be done preferably at the end of oestrum, as ovulation occurs 8-12 hours after the end of oestrum. If the heat signs continue a second insemination is advised.

Artificial Insemination

Artificial insemination in cattle

Crossbred bulls attain sexual maturity at about 24-36 months and semen collection can be started during this period. Before collection the bull may be given 1-2 false mounts in order to get maximum sperm harvest. From a mature bull usually two collections can be made at an interval of 2-3 days during a week.

Artificial insemination centres in India

Normal quality of bull semen used in artificial insemination

Preservation of semen

1. Chilled semen is stored under refrigeration temperature of 3^oC to 5^oC.

2. Frozen semen.

Number of sperms required per dose of diluted semen

Chilled semen – 15 millions

Frozen semen – 20 - 30 millions

Site of deposition of semen

While chilled semen is deposited in mid-cervix using glass pipette, frozen semen is deposited near the internal of cervix using A.I. gun.

Storing of frozen semen

Frozen semen is stored in liquid nitrogen at -196^oC. The straws are thawed in water at room temperature before use. Samples with less than 45% post-thaw motility should not be used.

Procedure for insemination with frozen semen

•  Raise the canister to the lower level of the neck of the liquid nitrogen refrigerator so that the top of the straw in the goblet is visible.

•  Using a pre-cooled forceps, take one straw from the goblet and dip it in a beaker containing water at room temperature for about a minute.

•  The straw is then taken out of the water and wiped with a clean towel to remove water sticking on the outside.

•  Hold it by the laboratory sealed end and give one or two jerks to bring the air space towards the lab-sealed end.

•  The lab sealed end of the straw is cut at right angle using a sterile scissors. Straw should not be cut obliquely, lest the semen leak into the sheath during insemination.

•  Push back the piston of the A.I. gun and put the straw into it with the factory sealed end down.

•  Slip the sheath over the gun and fix the plastic ring over the sheath. The gun is now ready for use.

•  Thawed semen should be used within 30 minutes for getting good fertility.

Embryo transfer

Multiple ovulation and embryo transfer is also a method for genetic improvement. Obtaining more progenies from the best cows is the objective. A cow which would normally produce one calf a year can be made to superovulate and produce multiple embryos. These embryos are transferred to recipient cows for further growth to full term and calving. The genetic improvement through embryo transfer depends on the actual superiority of the cow selected as donor, and the bull used for insemination. Moreover, the success rate of embryo harvest and transfer are key factors while adopting this technology. But the cost involved is very high at present. Embryo transfer can be successfully applied to produce good breeding bulls and also to enhance multiplication in case of endangered breeds.

The embryo transfer technology introduced in the recent past is yet another step towards livestock development. Of the total adult female cattle population in the State 83.4 percent is cross bred and if the cattle in milk is taken into consideration, it will increase to 85 percent and this was made possible by the Indo-Swiss Project and the expanded health care facilities and veterinary services.

Reproductive and productive parameters (Traits) in Indian cattle

H = Hariana, S = Sahiwal, RS = Red Sindhi, G = Gir, T = Tharparkar, R = Rathi, F = Friesian, BS = Brown Swiss, RD = Red Dane, J = Jersey

Gestation period

Gestation length is 275-285 days. Slight variation exists between breeds. Holstein Friesian and Brown Swiss crosses have a longer gestation length than other crosses. If gestation length exceeds 300 days, parturition will have to be induced. Few pregnant animals may exhibit oestrous symptoms.

Pregnant cows should be given at least 2 months dry period. Transfer the pregnant cows to calving pen at least 2-3 weeks before the expected date of calving.

Last updated: 23-8-2006