Observations on survival and growth to weaning of lambs from ewes with defective udders.

Abstract

Although work has been published showing relationships between milk production of the ewe and growth of the lamb, little has been done to investigate the effects of physical impairment or deficiency in mammary function in the ewe on the survival and growth of the lamb. This point has been studied by examining data for survival, birth weight, daily gain in weight to weaning age, and weaning weight from 621 Merino lambs born in the F. D. McMaster Field Station, C.S.I.R.O., flock from 1946 to 1949. When the performance of lambs from ewes having impaired or imperfect udder function was compared with that of lambs whose dams had normal function it was found that the lambs from ewes having defective function had a lower survival rate, a lower daily gain in weight to weaning age, and lower weight at weaning. The differences were statistically significant. Examination of the dry ewe flock in 1946 revealed that approximately 6 per cent. of all ewes aged from 1 to 7 years had damaged or imperfect udders. There was an association between age and incidence of defective udders, the incidence being highest among the oldest ewes. Culling of affected ewes from the flock was found to have very little effect in increasing the overall percentage of lambs raised to weaning age, or increasing their weaning weight. It is doubtful if culling for this fault would be beneficial in the average commercial Merino flock.

Associations between lamb growth to weaning and dam udder and teat scores

“…In the present study, offspring of ewes with clinical mastitis had lower growth rates. This is in agreement with previous studies in which lambs born to ewes with mastitis had reduced growth rates (Hayman et al 1955;Watson and Buswell 1984;Arsenault et al 2008). A variety of bacterial species have been identified as being involved in ovine mastitis in New Zealand commercial ewes (Quinlivan 1968(Quinlivan , 1972Clark 1980), with Staphylococcus aureus being of particular importance at lambing (Quinlivan 1972).…”

“…In this study, udder palpation score at all observation times was associated with lamb growth to weaning, with lower growth rates in lambs born to ewes with abnormal scores compared to those born to ewes with normal scores. There are limited comparable data available; Hayman et al (1955) reported lambs born to ewes with defective udders grew up to 34 g/day less than those born to ewes with normal udders, while Grant et al (2016) reported offspring of ewes with intramammary lumps grew 10 g/day less than those without lumps. Based on the results of the present study, and assuming a mean lamb age at weaning of 84.4 days, lambs born to ewes with abnormal udder palpation scores would on average be 1.0-2.9 kg lighter at weaning than those born to ewes with normal udder palpation scores.…”

“…Thus improving both lamb survival and growth to weaning improves total weaning weight, which is in turn closely correlated with the total weight of lambs sold. Lambs are dependent on their dam for milk for both survival and growth, with milk remaining an important source of digestible energy and protein to weaning (Hayman et al 1955;Glover 1972;Clark 1980). The quantity and quality of milk produced by the ewe are known to directly influence lamb growth (Hayman et al 1955;Clark 1980).…”

“…Lambs are dependent on their dam for milk for both survival and growth, with milk remaining an important source of digestible energy and protein to weaning (Hayman et al 1955;Glover 1972;Clark 1980). The quantity and quality of milk produced by the ewe are known to directly influence lamb growth (Hayman et al 1955;Clark 1980). Lambs born to ewes with poor udder health, low milk yield, poor colostrum quality or quantity have poorer growth rates (Hayman et al 1955;Watson and Buswell 1984;Arsenault et al 2008).…”

“…The quantity and quality of milk produced by the ewe are known to directly influence lamb growth (Hayman et al 1955;Clark 1980). Lambs born to ewes with poor udder health, low milk yield, poor colostrum quality or quantity have poorer growth rates (Hayman et al 1955;Watson and Buswell 1984;Arsenault et al 2008). Mastitis has an important impact on udder health and reduces both the quality and quantity of milk produced (Albenzio et al 2002;Leitner et al 2004).…”