- Aspects of kid mortality in South African Angora goats
|Last update: November 22, 2010 12:30:02 PM|
Aspects of kid mortality in South African Angora goats
M. A. Snyman
Grootfontein Agricultural Development Institute, Private Bag X529, Middelburg (EC), 5900, South Africa
email: Gretha Snyman
Reproduction and kid survival rate are the most important traits influencing income in Angora goats. High reproductive and kid survival rates will ensure a large proportion of the more expensive kid and young goat mohair in the clip, and will also contribute to higher selection intensity. The poor reproductive performance and high kid mortality rate of Angora goats are well documented. Factors influencing, the survival rate of kids include birth weight of the kid, genetic influences, mothering ability and milk production of the dam, adverse environmental or feeding conditions, diseases and predators. A study was done on 12 Angora goat studs to investigate the factors contributing to kid mortalities. In this paper, several aspects with regard to kid mortality rate from birth to weaning at 4 months of age will be discussed. Data recorded from 2000 to 2002 on 12 studs (± 4100 does, 3900 kids per year) were analysed. Average mortality rate from birth to weaning of kids in all studs over the three-year period was 10.7 %, varying from 5.7 % to 17.8 % among the different studs. In contrast with sheep, where mortality in lambs is typically related to birth weight by a V-shaped curve, the relationship between birth weight and mortality rate in Angora goats seems to be more curvi-linear than V-shaped. Kids with a birth weight below 2.0 kg, only had a survival rate of 50%, while more than 90% of kids with birth weights above 3.5 kg survived till weaning age. Several causes for kid mortalities were identified. The cause for 50 % of the recorded deaths is known. When the data were pooled for the three years, the biggest losses were due to predators (27.8 %), small, unthrifty kids who needed help suckling (16.5%), thick teats and udder problems (14.2%) and does having little or no milk (8.7%). The latter three categories, together with does discarding their kids, were responsible for 47% of pre-weaning mortalities. Over the three-year period a total of947 kids, born from 842 does, died between birth and weaning age. Of these does, 750 does only lost one kid, while 92 does lost two or more kids. Forty-one does lost kids in two years, while four does lost their kids in all three years. More than 50% of kid mortalities, where does lost kids in more than one year, were due to small, unthrifty kids who needed help suckling, does having thick teats and udder problems, does having little or no milk or does discarding their kids. This indicates that these problems will occur repeatedly in the same does. Does experiencing these kind of problems should preferably be eliminated, especially does with teat or udder problems. The relative importance of the various factors responsible for pre-weaning mortality in kids varied between the different studs. For example, predators was the main cause of death in a stud where kids were weaned on the veld, while udder and teat problems in does was the main cause of death in a stud where kids were weaned on pastures. Rather large variation in mortality rate of kids born to different sires within a specific stud was also observed. Overall, mortality rate ranged from zero to 50% losses among kids of different sires. Furthermore, the cause of death of kids born to different sires also varied. Several of the identified causes of kid mortality could be circumvented through management practices, for example, improved measures of predator control, ensuring adequate nutrition of pregnant does to ensure a viable birth weight of the kid and enough milk produced by the doe, as well as eliminating does with udder and teat defects. Differences between mortality rate of kids born to different sires also indicate a possible genetic contribution. The latter will be investigated when a further two year's data have been collected.