Analysis of an open nucleus breeding programme for Djallonkè sheep in the Ivory Coast. 1. Examination of non-genetic factors

Abstract

Data on Djallonke sheep collected from 1983 through 1992 on 29 participating farms of an open nucleus improvement programme and from the nucleus were analysed. Initial on-farm records on 14342 lambs and on-station records on 2551 ram lambs were edited down to 6605 for birth weight (BWT), 5857 for preselection (birth to 80 days) average daily gain (PSADG), 10417 for 80-day weight (WT80), 13054 for lamb survival at preselection, 1978 for 180 (WT180) and 849 for 365 (WT365) day weights. Year of birth, sire line, flock, month and season of birth had significant (at least P < 0-05) effects on both on-farm and on-station weights and on lamb survival. Trait means were 2-2 (s.e. 0-02) kg for BWT, 69-6 (s.e. 1-26) glday for PSADG, 9-1 (s.e. 0-05) kg for WT80, 197 (s.e. 0-24) kg for WT180 and 31-8 (s.e. 0-45) kg for WT365. Mean survival was 90 (s.e. 0-9) %. Single lambs were heavier at birth and at 80 days of age, grew faster to 80 days and were about 200 and 500 g heavier at 180 and 365 days respectively than multiple lambs. There was a large variation between flocks: flock means for WT80 varied from 6-4 to 12-0 kg (CV 0-21), with smaller flocks having generally the lowest means. Lambs born in the hot-rainy season had the heaviest birth and 80-day weights, whereas ram lambs born in the cool rainy and early hot-dry seasons had the heaviest 180-and 365-day weights. Lambs born during the cool months of July to October had the lowest survival rate. Multiplicative factors were found to be more appropriate for adjusting on-farm records for type of birth, management level, birth date, season of birth and ewe parity than additive adjustment factors.

Comparison of non-linear growth models to describe the growth curve in West African Dwarf sheep

“…Similar seasonal influences have been found in tropical area (London and Weniger, 1995;Ebangi et al, 1996) and may be due to the variation of the physical environment that affect the availability and quality of forage during dry season, since the year-round grazing was the practice in Betecoucou farm. The lambs weight consistently increased with ewe parity (Figure 3a) as described in other studies (London and Weniger, 1995;Ebangi et al, 1996;Yapi-Gnaoré et al, 1997). The maternal effect (i.e.…”

“…the twins was similarly reported (Armbruster et al, 1991a;Abassa et al, 1992;Yapi-Gnaoré et al, 1997) and in this case, the limited capacity of WAD dams to provide more nourishment for the development of multiple foetuses and more milk for new born lambs, could explain their low performance. The lambs born in rainy season were heavier and grew faster than their counterparts from the dry season (Figure 2c).…”

“…The observed minus predicted weight shows that the Brody model under predicted (Figure 1a) by 20.64 and 20.21 kg at 30 days and 60 days, respectively, and by 20.48 and 20.33 kg at 150 and 180 days weight, respectively. Inversely, the birth weight, 90 days and 120 days (Armbruster et al, 1991a and1991b;London and Weniger, 1995;Yapi-Gnaoré et al, 1997); 6.02 kg at 60 days of age (London and Weniger, 1995); 9.1 kg at 80 days of age (YapiGnaoré et al, 1997); 6.99 to 12.7 kg at 90 days of age (Poivey et al, 1986;Armbruster et al, 1991b;London and Weniger, 1995;Yapi-Gnaoré et al, 1997); 8.71 kg at 120 days of age (Fall et al, 1982); 15.1 kg at 180 days of age (Poivey et al, 1986). Gbangboche et al (2006a) reported the mean body weight of 27.5 6 2.4 kg at 1.7 years, and London and Weniger (1995), 20.9 and 23.6 kg at 3.5 and 4 years of age.…”

“…In Benin, the WAD sheep is raised exclusively for meat and was estimated at 700 000 (Faostat, 2005), and play an important economical, social and cultural roles. For this purpose in West and Central Africa, the genetic and non-genetic effects on the growth performance of WAD sheep had become an attractive study in last decades to improve overall productivity (London and Weniger, 1995;Yapi-Gnaoré et al, 1997;Gbangboche et al, 2006a and2006b). However, the advantage of growth models such as Logistic and Gompertz (Renne et al, 2003;Lambe et al, 2006), Von Bertalanffy (Topal et al, 2004) and Brody model (Bathaei and Leroy, 1998), which give an explanation of what is biologically occurring during the growth phase of an animal, and their importance on breeding program (Varona et al, 1997;Lewis and Brotherstone, 2002) were unknown in WAD sheep.…”

Effect of Intensive and Semi-intensive Feeding System on Productive and Reproductive Performances of Native Sheep

“…The mean weight at weaning was recorded 7.3 kg and 7.7 kg, respectively for semi-intensive and intensive management system. Different weaning weights have been reported 8.41 kg at 105 days [15]); 9.5 kg for weaning at 105 days [16]) and 12.7 kg at 90-120 days [17]. Average milk yield was not significantly (p > 0.05) higher (264.5g/d) in intensive system than semi-intensive feeding system (281.0g/d).…”