Mortality in small stock

Mortality of lambs and kids is one of the main factors adversely affecting sheep and goat production. An essential factor affecting return on investment in sheep and goat production is pre-weaning mortality. The highest losses usually occur during the first 30 days of life.

Causes of lamb/kid mortality

Causes of mortality are related to management and production system. Some of the causes are:

  • Low birth weight
  • Low environmental temperature at birth or shortly
  • Litter type (single or multiple)Inadequate colostrum consumption
  • Inadequate milk production of the dam
  • Predators
  • Diseases and accidents
  • Season of birth

It has to be noted that all of these could be aggravated by poor management such as poor hygiene and overcrowding.

Low birth weight: Lambs/kids having low birth weight are consistently at risk of dying at all stages of development (pre- and post-weaning). Low birth weight is usually caused by inadequate nutrition of the dams during the last period of gestation. Low birth weight can be prevented where supplementary feeding of dams is practiced or when there is adequate forage of reasonable quality.

Low temperature: Very often this is a problem encountered in the cool highlands where the ambient temperature falls below zero during some months of the year. In such circumstances, the newborn can die as a result of hypothermia unless it is protected against freezing temperatures. The newborn could be put in a lamb/kid box for the first few days to provide protection against cold.

Predators: If ewes/does are giving birth unobserved on the range, the newborns are exposed to predators or kids/lambs may be abandoned by their dams. Abandonment may happen frequently with first time mothers. Losses due to predators have been reported to be a major cause of kid loss in Botswana.

Diseases: If lambing/kidding is unattended and appropriate management measures such as dipping the navel cord in iodine are not done, the chance of infection increases. Proper preventive management and attention to health and cleanliness of the rearing area will decrease the chance of acquiring diseases.

Dehydration: If lambs/kids are allowed to join their mothers grazing on the range and travel long distances in their first days of life they may suffer dehydration. If there is no shelter to protect them from the extremes of weather, they may suffer from heat or cold, especially if in combination with humidity. It is advisable to house the young and the dams for at least the first few days after birth before allowing them to graze with the flock.

Litter type: Mortality is higher in lambs/kids born in multiple litters than single-born lambs and kids. This might be a reflection of low birth weight, and inadequate nutrition in terms of milk from their dams as well as poor supplementary feeding management.

Season of birth: The effect of season varies for different places and seems to be related to nutrition of the dam, climatic condition and other factors as well as the presence of disease. For instance, kids born in the wet season have better survival than kids born in the dry season.

Reducing kid mortality

Reducing kid mortality focuses on two key issues:

  • Improving birth weight of newborns by supplementary feeding of pregnant animals during the last period of pregnancy.
  • Following standard hygienic practices to prevent/reduce incidence of diseases that affect young animals.