Environmental and genetic causes of variation in production traits of Damascus goats. 1. Pre-weaning and post-weaning growth

Abstract

Data on 1542 Damascus kids, collected from 1977 to 1981, were used to study environmental and genetic factors influencing pre-weaning and post-weaning growth traits of kids. Season of birth, type of birth, sex of kid and dam lactation number were the environmental factors investigated. Phenotypic and genetic parameters were estimated from paternal half-sib correlations. The average sire family size was 17·2 kids. Single kids were heavier at birth, at weaning and at 140 days of age than twins or other multiples (P < 0·01). Male kids were heavier (P < 0·01) and grew faster (P < 0·01) than female kids from birth to 140 days of age (4·7 and 4·2 at birth, and 29·2 and 24·6 kg at 140 days, respectively). Dam lactation number significantly affected pre-weaning growth, but had no effect on the post-weaning growth rate of kids.Heritabilities for birth, weaning and 140-day weights, and pre-weaning and post-weaning growth rate, were 0·31 (s.e. 0·08), 0·27 (s.e. 0·07), 0·21 (s.e. 0·07), 0·16 (s.e. 0·06) and 0·22 (s.e. 0·07), respectively. Genetic correlations were mostly high and all positive, especially between weaning weight and 140-day weight (0·82 (s.e. 0·08)), and pre-weaning growth rate and 140-day weight (0·80 (s.e. 0·10)). The corresponding phenotypic correlations were also high and positive (0·71 and 0·67, respectively). No genetic antagonisms were found among the characters studied. Response to selection for post-weaning growth should be effective.

Environmental and genetic effects on birth weight in graded-up goat kids

“…Results are in agreement with studies showing that kid birth weight increases with doe parity (Mavrogenis et al 1984;Singh et al 1984;Nagpal and Chawla 1985) and these may be partly explained by an increase in doe weight (Roy et al 1989 (3.08-3.11 kg) than kids born in the April-June period (3.25ke; Table 3). Significant year and kidding period effects on birth weight are well documented (Singh et al 1984;Sivaiah et al 1988;Nagpal and Chawla 1985;Roy et al 1989;Singh et al 1990).…”

“…Male kids were heavier than females (3.37 vs. 2.91 kg), singles (3.37 kg) were heavier than doubles (3.18 kg) and doubles were heavier than triplets (2.88 kg; Table 3). The effect of the sex of kid and the type of kidding on birth weight, as found in this work, is well documented (Montaldo andJuiirez 1981; Mavrogenis et al 1984;Singh et al 1984;Fernandes et al 1985;Nagpal and Chawla 1985;Sivaiah et al 1988;Roy et al 1989;Bajhau and Kennedy 1990;Jagtap et al 1990;Mishra and Ghei 1990;Singh et al 1990). …”

“…Nevertheless, analysis on genetic group by birth period subclass means showed that the tendency mentioned above Montaldo and Jui{rez (1981) with high-grade goats in the same flock, by Madeli and Patro (1984) in Ganjam goats, by Mavrogenis et al (1984) in Damascus goats and by Roy et al (1989) …”

“…Le poids ii la naissance s'est accrue avec I'Age de la mEre. Les moyennes du poids ir la naissance en haut-niveau et crois6s ont 6te (Mavrogenis et al 1984). To date, no work has been perliveweights (Madeli and Patro 1984;Mavrogenis et al 1984; formed to compare heritability estimates for this trait in Roy et al 1989).…”

“…Les moyennes du poids ir la naissance en haut-niveau et crois6s ont 6te (Mavrogenis et al 1984). To date, no work has been perliveweights (Madeli and Patro 1984;Mavrogenis et al 1984; formed to compare heritability estimates for this trait in Roy et al 1989). Therefore, birth weight could be utilised purebreed and crossbreed kids from principal breeds utilized to choose among populations, or as a preliminary selection in Mexico. criteria in a given population, particularly in production The objective of this work was thus to determine breed systems where the kid is slaughtered at a very early age as differences in birth weight at two levels of backcross (low-in Northern Mexico (Montaldo and Jur{rez 1981 All the first order interactions were tested in a preliminary analysis and were excluded from the model when they were non-significant (P > 0.05).…”