The effect of footrot on weight gain in sheep

Abstract

Footrot is a highly contagious bacterial disease of sheep affecting the interdigital skin and surrounding soft and hard horn of a hoof, often resulting in severe lameness. This study was aimed at estimating the effect of footrot on weight gain of affected animals, and characterising the variation between animals in terms of phenotypic, environmental and genetic components. A general approach was developed describing the relationship between the disease and weight gain, defining new traits such as the maximum weight loss as a result of disease and the time after infection that this occurs. In two trials, 1267 Merino sheep were artificially challenged with footrot when 10 months old and re-infected through exposure to footrot on pasture 33 weeks later. Their feet were scored for footrot and live weights were measured approximately every 3 weeks. From data on animals that were not affected by footrot throughout each trial, normal growth curves were calculated and applied to affected animals to predict their growth had they remained healthy, so that weight loss as a result of footrot could be predicted. Animals with average footrot severity in the two trials suffered weight losses of 0.5 to 2.5 kg live weight, but most animals regained lost live weight later in the trials as footrot healed following vaccination. The estimates of the heritabilities of weight loss, adjusted for the severity of footrot, were about 0.30 and 0.15 in the experimental and natural challenge groups, respectively. Animals with higher genotypic values for weights at the start of each trial appeared to cope better with infections, in terms of lower weight losses. The time of highest footrot score and the time of maximum weight loss after infection had only very small genetic components.

Breeding objectives for sheep in Ireland: A bio-economic approach

“…A number of studies have investigated eradication and control strategies (Ennen et al, 2009;Winter, 2009), validation of scoring methods (Conington et al, 2008), and the impact foot rot has on production (Nieuwhof et al, 2008a). This paper presents the development of economic weights for foot rot.…”

Aetiology, Risk Factors, Diagnosis and Control of Foot-Related Lameness in Dairy Sheep

“…Considerable research efforts have focused on the investigation of foot-related lameness and its epizootiology, pathogenesis, diagnostic capabilities, and the impact on production, health and welfare status, as well as on the development of effective treatments and application of sustainable preventive measures. The majority of relevant research efforts have focused primarily on cattle [4,5,6,7,8,9,10,11], meat and wool sheep [12,13,14,15], and dairy goats [16,17], highlighting the impact of foot-related lameness on several production traits in these species [12,13,14,15]. Although relevant studies in dairy sheep are limited, recent evidence has suggested a detrimental effect of foot-related lameness on both their well-being and productive efficiency [18,19,20].…”

Cost–benefit analysis of management practices for ewes lame with footrot

“…Economic losses from lameness occur in ewes left untreated for one week (Wassink et al, 2010b). Losses arise from ewe deaths and infertility, reduced numbers of lambs born and surviving, and reduced lamb growth rates (Stewart et al, 1984;Marshall et al, 1991;Nieuwhof et al, 2008;Wassink et al, 2010b).…”