ANIMAL REPRODUCTION
OBJECTIVE
General
Conduct research to improve reproductive efficiency
of domestic ruminants
Specific
Research on extenders and processing techniques of semen preservation to improve conception rate with artificial insemination in buffalo.
Introduction of artificial insemination in goat.
Study of hormonal and management inputs to overcome summer anoestrous in buffalo.
RESEARCH ACHIEVEMENTS
Multiple ovulation and embryo transfer (MOET)
First embryo transfer calf in Pakistan was born at NARC in 1987 fallowed by first embryo transfer lamb in 1992. The technique has not been so far applied in buffalo due to poor embryo recovery.
Semen preservation and artificial insemination (AI) in farm animals
Artificial insemination (AI) is the most important single technique devised for the genetic improvement of animals, because a few selected males produce enough sperm to inseminate thousands of females per year. The salient achievements in this area are:
Tris–citric acid based extender was tested to replace the conventional Na-citrate buffer for the freezing of buffalo and cattle semen. An improved conception rate (53% vs 29%) was achieved in the field trials with semen frozen in Tris–citric acid extender.
Chilled (5 °C) semen is another available technique for AI. Research in this area showed that skim milk is the best preservative among five different extenders including cow milk, buffalo milk, camel milk and homogenized UHT milk. Application of this technique, due to simplicity, may prove more effective in successful introduction of AI in the remote areas of the country.
The addition of antioxidant in the freezing diluents exerts a protective effect against lipid peroxidation, thereby preserving the metabolic activity and cellular viability of sperm. Use of antioxidant in semen extender was tested to improve the viability of frozen-thawed semen. The preliminary results indicated that addition of antioxidants in extender improved the quality of buffalo semen processed for cryopreservation.
Thawing and carrying semen in ice water: A user friendly semen carrying method was proposed to carry frozen-thawed semen for AI in cattle/buffalo. Progressive motility of frozen buffalo or Sahiwal semen carried in ice water declined gradually to around 50% of control over three hours. There was about a 20% decline in fertility when inseminations were made after holding semen for 30 to 60 min in ice water in buffalo. This method may be convenient for AI technician when insemination would be performed within 30 min after removing frozen semen from liquid nitrogen container.
In vitro bull fertility tests
In spite of the stringent methods used for the
selection of donor AI bulls, fertility levels of bulls vary widely in the field,
and a fair percentage of bulls show below average fertility.
Identification of high fertility semen donor bulls for AI would increase its
popularity among farmers. The potential fertility of bulls can be measured with
field fertility rates, but this procedure is expensive and time consuming.
Therefore studies were carried out to standardize methods of in vitro
fertilization for field fertility of bulls. In vitro fertilization rate of
oocyte was found to be an effective method for assessing in vivo fertilizing
ability of bulls.
Pregnancy test in sheep/goat using ultrasonography
Pregnancy test procedure with ultrasonography was
standardized in local sheep. Cent percent accuracy of pregnancy diagnosis in
Balkhi ewes was achieved at day 42 of gestation by transabdominal
ultrasonography using a 3.5 MHz probe. Flock pregnancy test on Balkhi ewes
conducted 75 days after introduction of ram was 97% accurate.
Summer anoestrous in buffalo
Estrous activity lacks or is significantly reduced
in buffalo over a part of the year (February to August). This problem
significantly affects regular milk supply especially in the peri-urban dairy
farms. Increasing day-light and high temperature stress have been ascribed to be
the causes of long anoestrus period in buffaloes. Estrous induction with
hormones and insemination has been used as a useful reproductive management tool
in cows and sheep to breed them at desired time of the year. The same was tried
with buffaloes.
Progesterone implant was tested to induce heat in
buffaloes during low breeding season (April May). Heat signs were noted in 80%
animals after withdrawal of implant. A conception rate of 30% was observed at
first service immediately after hormone withdrawal. A second service in 20%
animals 21 days later resulted in a total conception rate of 40% in summer
season.
Kids born through artificial insemination in goats
SCIENTIFIC STAFF
1. Dr. M. Anwar, PSO
2. Dr. Abid Mehmood, PSO
3. Dr. SMH Andrabi, SSO