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5. (a) Sheep are polyoestrous - Leaving Cert Agricultural Science - Question 5 - 2015
Question 5
5. (a) Sheep are polyoestrous. What does the term polyoestrous mean? (b) What is the length of the oestrous cycle in sheep? (c) Explain the connection between ... show full transcript
Worked Solution & Example Answer:5. (a) Sheep are polyoestrous - Leaving Cert Agricultural Science - Question 5 - 2015
Step 1
What does the term polyoestrous mean?
Answer
Polyoestrous refers to the physiological ability of sheep to have multiple oestrous cycles within a breeding season or to come into heat more than once during a particular breeding period. This characteristic allows sheep to breed more than once a year, enhancing reproductive efficiency.
Step 2
Step 3
Explain the connection between day length and the breeding season in sheep.
Answer
The breeding season in sheep is closely linked to the length of the day, as shorter days signal the approach of autumn. When the days become shorter, the amount of sunlight decreases, which in turn lowers the production of melatonin by the pineal gland. This hormonal change stimulates ovulation and synchronizes the breeding cycle, making it easier for farmers to manage reproduction in sheep.
Step 4
Draw a large labelled diagram of the reproductive system of a ewe and label four parts.
Answer
The diagram should include the ovaries, oviducts, uterus, and vagina.
- Ovaries: Responsible for producing eggs.
- Oviducts: Channels through which eggs travel from the ovaries to the uterus.
- Uterus: The organ where fertilized eggs develop into lambs.
- Vagina: The passage leading from the external genitals to the cervix.
Step 5
Describe the key steps involved in 'breeding out of season' to produce lambs for the early spring market.
Answer
Breeding out of season involves several critical steps:
- Heat Synchronization: Use hormonal treatments to control and synchronize the estrous cycle of ewes.
- Artificial Insemination: Breed ewes with either fresh or frozen semen during their synchronized heat period.
- Nutritional Management: Provide ewes with a balanced diet to promote reproductive health and support lambing.
- Monitoring: Regularly check for signs of pregnancy and manage the flock accordingly to ensure optimal lambing success.
Step 6
Outline four reasons for culling ewes.
Answer
Reasons for culling ewes include:
- Udder Damage: Ewes with damaged udders may be unable to nurse their lambs effectively, impacting lamb survival.
- Barren or Infertile: Ewes that consistently fail to breed or produce lambs reduce overall flock productivity.
- Age: Older ewes might have decreased fertility or health issues that warrant culling.
- Poor Condition: Ewes that exhibit poor body condition scores may not support healthy pregnancies or lamb rearing.