Neonatal lamb mortality: factors associated with the death of Australian lambs

Abstract

The objective of the present study was to examine the factors associated with the death of neonatal lambs. Postmortem autopsy data were collected from 3198 newborn lambs in the Sheep CRCs Information Nucleus Flock situated in various environments throughout southern Australia. The proportion dying by category from highest to lowest was starvation–mismothering (25%), stillbirth (21%), birth injury (18%), dystocia (9%), death in utero–prematurity (10%), predation (7%), cold exposure (5%), undiagnosed (4%), infection (1%) or misadventure (1%). Factors best explaining the probability of lambs falling into a death category included both birth type and birthweight for dystocia, stillbirth, starvation–mismothering and death in utero–prematurity. The probability of a lamb falling into any category was predicted at the mean birthweight, within birth type. Single-born lambs were more likely to die from dystocia and stillbirth, while twin lambs were more likely to die from birth injury, starvation–mismothering or from undiagnosed causes. Triplet lambs were more likely to die from starvation–mismothering or death in utero–prematurity. Sire type (Merino, maternal or terminal) did not affect the proportions of lambs within any category. The proportions lost to each cause of death were largely consistent among locations, despite the rate of death varying. Dystocia, stillbirth and birth injury, as evidenced by the presence of oedema around the head and neck or by lesions of the central nervous system, accounted for 48% of autopsied lambs. We conclude that for improvements to occur in the rates of lamb survival, the Australian sheep industry must focus on minimising losses due to dystocia, stillbirth, birth injury and starvation.

Maternal Supplementation with Dietary Betaine during Gestation to Improve Twin Lamb Survival

“…Despite this, we cannot dismiss the possibility that EB lambs experienced some symptoms related to HIE, and thus, caused long-term neurodevelopment morbidities that ultimately resulted in the observed mortalities. However, this suggestion is inconsistent with the study by Refshauge et al [ 5 ] who found that since the majority of these losses did not occur around parturition, they are less likely to be caused by labour difficulties and more likely to be attributed to misadventure and exposure. This conclusion is supported by the findings from several lamb autopsies conducted in the current study, which indicated the cause of death was primarily due to hypothermia.…”

“…This equates to an estimated loss of around $540 million per annum [ 3 ] and represents a significant economic and welfare concern. Lambs are most vulnerable during the first 72 h of their life, with 43 to 70% of perinatal deaths occurring during this period [ 4 , 5 , 6 ]. Approximately 50% of deaths arise from complications occurring in utero and/or immediately following birth: stillbirth, dystocia and hypoxic birth injury [ 5 , 6 ].…”

“…Lambs are most vulnerable during the first 72 h of their life, with 43 to 70% of perinatal deaths occurring during this period [ 4 , 5 , 6 ]. Approximately 50% of deaths arise from complications occurring in utero and/or immediately following birth: stillbirth, dystocia and hypoxic birth injury [ 5 , 6 ]. Twin-born lambs are lighter at birth [ 7 ] and often have impaired thermoregulatory ability due to poor accumulation of energy reserves [ 8 ].…”

A Survey of New South Wales Sheep Producer Practices and Perceptions on Lamb Mortality and Ewe Supplementation

“…These reported values are between the 30% mortality reported by Geenty, Brien [3] and the 58.2% noted by Luff [30]. Mortality due to starvation is consistently high across studies [34], representing an overall general issue in the sheep industry from a variety of causes such as slow-onset milk production, low mothering ability, poor nutrition, and/or lamb factors.…”

A Review on the Influence of Climate Change on Sheep Reproduction

“…Lamb marking percentages in Australia have changed little for many generations [79,80], despite improvements in breeding, nutrition and tools for managing pregnant ewes [80,81]. The wider influence and effects of climate change on lamb marking percentages is yet to be researched.…”