Dr. G van der Veen (BVSc) Technical manager: Ruminants [email protected]

Transcription

1 Dr. G van der Veen (BVSc) Technical manager: Ruminants [email protected]

2 GENETICS NUTRITION MANAGEMENT

3 Improved productivity and quality GENETICS Breeding programs are: Optimize genetic progress Translate into long-term economic profitability 1 Genetic improvement are governed by four key factors 2 : 1. The intensity of selection The proportion of animals chosen for a particular breeding program 2. Accuracy of selection Refer to the correctness of which genetically superior animals are selected as replacements for the current herd. 3. Genetic standard deviation Genetic variation within a herd 4. Generation interval The amount of time required to replace one generation with the next.

4 GENETICS Estimated breeding values Measure the genetic strength of performance Performance of both the individual and its close relatives Best Linear Unbiased Prediction (BLUP) and Molecular methods Track the inheritance of particular genes Allows earlier selection PHENOTYPE = GENETICS + ENVIRONMENT

5 GENETICS HERITABILITY VALUES and its advantages for the farmer: Parasite resistance Disease resistance Improved production measurements (3) (4)

6 Genetically superior animals can be selected with a high degree of accuracy, but Conventional breeding programs are still hampered by 1 : Limited male and female lifetime reproduction Long generation intervals GENETICS Assisted Reproductive Technologies 1 Significantly accelerate genetic progress by: Influencing all four factors included in the genetic gain formula Enhance both the male and female pathways of gene transmission Males = Artificial insemination Females = multiple ovulation and embryo transfer programs

7 MANAGEMENT Seasonal and non-seasonal breeding

8 MANAGEMENT Vaccination and deworming G2818 (Act 36/1947) G2347 Act (36/1947) G3889 (Act 36/1947) G3449 (Act 36/1947)

9 Preparation of the rams MANAGEMENT 5

10 MANAGEMENT Ultrasound pregnancy diagnosis

11 MANAGEMENT Lambing (reduced lamb losses)

12 MANAGEMENT Lamb processing (tail docking, castration and vaccination)

13 MANAGEMENT Uniform lamb crop for marketing

14 NUTRITION 19 weeks where the level of nutrition can effect the reproductive potential 3 weeks before the breeding season Flush feeding (ovulation) 4 weeks after conception loss of embryos 6 weeks before lambing Growth of fetus and colostrum 6 weeks after lambing Feed only ewes that are profitable Pregnancy toxaemia Late gestation BCS <2 or >4 and carrying >1 fetus Ewes with twin lambs require x more energy and protein

15 Oestrus Synchronisation for Sheep

16 Oestrus Synchronisation for Goats

17 Oestrus Synchronisation for Sheep Cervical AI: Dorper, Goats and Hair sheep Autumn Adult Maiden CIDR s Spring Adult Maiden CIDR s Cervical AI: Wool sheep Autumn Adult Maiden CIDR s Spring Adult Maiden CIDR s

18 Advantages of Synchronization and AI Shorter lambing periods. All ewes that conceive after synchronization lamb during one week most over 3day period. Lambing times can be planned. Lambs are the same age facilitates management during ID and weaning. A larger amount of lambs can be marketed at the same time. Ultrasound pregnancy diagnoses can be done more accurately 42 d after AI/mating. Save on feeding costs by eg. flush feeding only for 4 weeks in advance of breeding and lambing. Better lambing observation and lower loss to predators during that time(>70 %loss in first 48hours). Lambing pens can be used optimally.

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20 References (1) Candappa IB, Bartlewski PM. A review of advances in artificial insemination (AI) and embryo transfer (ET) in sheep, with the special reference to hormonal induction of cervical dilation and its implications for controlled animal reproduction and surgical techniques. Open Reproductive Science Journal 2011;3: (2) Dekkers J. Structure of breeding programs to capitalize on reproductive technology for genetic improvement. J Dairy Sci 1992;75(10): (3) Raadsma HW, Gray GD, Woolaston RR. Breeding for disease resistance in Merino sheep in Australia. Rev Sci Tech 1998 Apr;17(1): (4) Notter D. Genetic aspects of reproduction in sheep. Reproduction in Domestic Animals 2008;43(s2): (5) Bath G, Van Wyk J. The Five Point Check for targeted selective treatment of internal parasites in small ruminants. Small Ruminant Research 2009;86(1):6-13.