- Geboorte- en speenmassa van herfs en lentegepaarde lammers
|Last update: April 3, 2012 11:35:15 AM|
GEBOORTE- EN SPEENMASSA VAN HERFS- EN LENTEGEBORE LAMMERS
P. G. MARAIS en P. S. PRETORIUS
Ten einde 'n vergelyking te tref tussen die geboorte- en speenmassa van lammers, is 2 684 Merino-ooie en hul 2 627 lammers oor 'n tydperk van ses jaar gedurende twee paarseisoene, t.w. herfs en lente, bestudeer. Lentegebore lammers het die voordeel bo herfsgebore lammers dat die gemiddelde massa lam gebore per ooi beskikbaar vir paring, 1,3 kg meer is en dat die gemiddelde geboortemassa 0,6 kg hoër is. Hoewel herfslammers se gemiddelde speenmassa 5,5 kg hoër is as die van lentelammers, is die massa lam gespeen per ooi beskikbaar vir paring 2,56 kg hoër by lente- as by herfslammers.
BIRTH AND WEANING MASS OF AUTUMN AND SPRING BORN LAMBS
In order to investigate the difference in birth and weaning mass between autumn and spring born lambs, the breeding records of2 634 Merino ewes and their 2 627 lambs were analysed over a period of six years, with two mating seasons per year. The latter included autumn (March to April) and spring mating (September to October) seasons. It was found that spring lambs had a higher birth mass and that the difference of 0,6 kg between autumn and spring lambs was highly significant (P<0,01). A further advantage is contained in the fact that the mass of "lamb born per ewe joined" was significantly higher for spring born lambs (P<0,05). Furthermore the average weaning mass of autumn lambs was significantly superior to those of spring lambs by 5,5 kg (P<0,01). However, according to the mass of "lamb weaned per ewe joined", the statistically significant difference of 2,56 kg (P<0,05) was significantly in favour of spring lambs. The latter result was ascribed to a higher incidence of twins among spring lambs.