1  Introduction

• 1.1 Statement of the problem

2  Review of literature

• 2.1 Production performance of sheep with relevance to the tropics

  • 2.1.1 Performance of mutton sheep breeds and their crosses under tropical conditions

    • 2.1.1.1 Growth performance

    • 2.1.1.2  Importance of vlies

    • 2.1.1.3 Milk yield performance

  • 2.1.2 Effect of restricted feeding and realimentation on growth

    • 2.1.2.1 Effect of restricted feeding

    • 2.1.2.2 Effect of realimentation on growth

  • 2.1.3 Physiological reaction to high ambient temperature

    • 2.1.3.1 Effect on body temperature

    • 2.1.3.2  Effect on breathing rate

    • 2.1.3.3 Effect on feed intake and digestibility

    • 2.1.3.4 Effect on production

3  Main findings from survey of literature and objective

4  Materials and Methods

• 4.1 Comparative pre-weaning growth performance of lambs of different genotypes

  • 4.1.1 Animals used

  • 4.1.2 Feeding

  • 4.1.3 Housing of animals

  • 4.1.4 Management of experimental animals

• 4.2 Milk yield performance of Cameroon and C1 ewes rearing lambs using the suckling method

  • 4.2.1 Animals used

  • 4.2.2 Feeding

  • 4.2.3 Housing of animals

  • 4.2.4 Management of experimental animals

• 4.3 Comparative post-weaning growth performance of lambs of different genotypes

  • 4.3.1 Influence of different feeding levels

    • 4.3.1.1 Animals used

    • 4.3.1.2 Feeding

    • 4.3.1.3 Housing of animals

    • 4.3.1.4 Management of experimental animals

  • 4.3.2 Reaction to high ambient temperature during the day and of alternating feeding levels

    • 4.3.2.1 Animals used

    • 4.3.2.2 Feeding

    • 4.3.2.3 Housing of animals

    • 4.3.2.4 Management of experimental animals

• 4.4 Carcass evaluation

• 4.5 Analysis of data

• 4.6 Basic models of the experiments

5  Results

• 5.1 Pre-weaning growth performance of lambs

• 5.2 Milk yield performance of Cameroon and C1 ewes using the suckling method

• 5.3 Comparative post-weaning growth performance of lambs of different genotypes

  • 5.3.1 Influence of different feeding levels on performance

  • 5.3.2 Reaction to high ambient temperature during the day and of alternating feeding levels

    • 5.3.2.1 Post-weaning growth performance

    • 5.3.2.2 Physiological reaction to high ambient temperature

• 5.4 Carcass evaluation

  • 5.4.1 Influence of different feeding levels on performance

  • 5.4.2 Reaction to high ambient temperature during the day and of alternating feeding levels

  • 5.4.3 Distribution of internal fat in response to different levels of feeding under stall temperature conditions (1995) and high ambient temperature during the day with alternating feeding levels (1996)

6  Discussion

• 6.1 Comparative pre-weaning growth performance of lambs of different genotypes

• 6.2 Milk yield performance of Cameroon and C1 ewes using the suckling method

• 6.3 Comparative post-weaning growth performance of lambs of different genotypes

  • 6.3.1 Influence of different feeding levels on performance

  • 6.3.2  Reaction to high ambient temperature during the day and of alternating feeding levels

• 6.4 Pattern of deposition of kidney and mesenteric fat of slaughtered lambs following exposure to different feeding levels under stall ambient temperature conditions (1995) and to high ambient temperature during the day with alternating feeding levels (1996)

• 6.5 Limitations related to experimental conditions

7  Summary

• 7.1 Comparative pre-weaning growth performance of lambs of different genotypes

• 7.2 Milk yield performance of Cameroon and C1 ewes using the suckling method

• 7.3  Comparative post-weaning growth performance of lambs of different genotypes

  • 7.3.1 Influence of different feeding levels on performance

  • 7.3.2 Reaction to high ambient temperature during the day and of alternating feeding levels

• 7.4 Carcass evaluation

  • 7.4.1 Influence of different feeding levels on performance

  • 7.4.2  Reaction to high ambient temperature during the day and of alternating feeding levels

Table 1: Birth weight and Average Daily Gain performance of hair sheep and their crosses

Table 2: Effects of increasing ambient temperature on the rectal and rumen temperature of wethers fed a low, average and high energy ration.

Table 3: Effect of increasing ambient temperature on breathing rate of wethers fed a low, average and high energy ration

Table 4: Effect of increasing ambient temperature (°C) on DM and raw fibre intake

Table 5: Results of ANOVA for birth weight and pre-weaning growth of lambs

Table 6: Effects of genotype and sex on birth weight and pre-weaning live weight of lambs, , LSQ-means ± se

Table 7: Effects of genotype and sex on pre-weaning average daily gain of lambs, LSQ-means ± se

Table 8: Results of ANOVA for milk yield performance of ewes

Table 9: Influence of genotype on milk yield performance of ewes during 9 weeks of lactation, means ± se

Table 10: Results of ANOVA for post-weaning growth, energy and feed intake of lambs

Table 11: Effects of genotype and feeding level on post-weaning growth, energy and feed intake, means ± se

Continuation: Table 11

Table 12: Means and standard errors of live body weight, growth and feed intake of lambs of different genotypes in response to different feeding levels

Table 13: Results of ANOVA of post-weaning live weight, ADG and energy and feed intake of lambs per week

Table 14: Means and standard errors of post-weaning live weight, ADG and energy and feed intake of lambs per week by genotype and sex

Continuation: Table 14

Table 15: Results of ANOVA for rectal temperature and breathing rate per minute during the high, low and high feeding phases and over the whole experimental period

Table 16: Rectal temperature and breathing rate per minute of lambs during the different feeding level phases at high and low ambient temperature, means ± se

Table 17: Results of ANOVA of absolute and relative weights of important parts of the carcass of lambs and of measures of carcass quality, 1995

Continuation: Table 17

Table 18: Means and standard errors of absolute and relative weights of important parts of the carcass of lambs and of measures of carcass quality, 1995

Continuation: Table 18

Continuation: Table 18

Table 19: Results of ANOVA of absolute and relative weights of important parts of the carcass of lambs and of measures of carcass quality, 1996

Continuation: Table 19

Continuation: Table 19

Table 20: Means and standard errors of absolute and relative weights of important parts of the carcass of lambs and of measures of carcass quality, 1996

Continuation: Table 20

Continuation: Table 20

Table 21: Results of ANOVA of relative deposition of total fat*, kidney and mesenteric fat of slaughtered lambs by treatment, genotype and sex in 1995 and 1996

Table 22: Relative means and standard errors reflecting the pattern of deposition of total fat, kidney and mesenteric fat of slaughtered lambs by treatment, genotype and sex in 1995 and 1996.

Fig. 1: Milk performance of Cameroon and C1 ewes during 9 weeks of lactation

Fig. 2: Post-weaning live body weight of lambs: Reaction to different feeding levels

Fig. 3: Average Daily Gain in response to High-Low feeding

Fig. 4: Average Daily Gain in response to Low-High feeding

Fig. 5: Mean percentage wheat straw intake of lambs in the High-Low feeding treatment

Fig. 6: Mean daily concentrated feed intake of lambs subjected to high ambient temperature and alternating feeding levels

Fig. 7: Intake of energy above maintenance level by lambs subjected to high ambient temperature and alternating feeding levels

Fig. 8: Mean daily wheat straw intake of lambs subjected to high ambient temperature and alternating feeding levels

Fig. 9: Mean percentage wheat straw intake of lambs in response at high temperature and alternating feeding levels

Fig. 10: Effect of fluctuating temperatures (high and low during the day and at night, respectively) on rectal temperature of Cameroon and Cameroon x Mutton lambs during the post-weaning growth phase

Fig. 11: Effect of fluctuating temperatures (high and low during the day and at night, respectively) on breathing rate of Cameroon and Cameroon x Mutton lambs during the post-weaning growth phase