Chitosan oligosaccharide, a new food additive, can be incorporated into sheep feed to benefit both ewe and lambs

Chitosan oligosaccharide (COS) is a type ofoligosaccharide isolated from the shells of crustaceans.Dietary COS may be of benefit to the gut microbiota,boosting immune status and health of its host. The inclusion of COS in sheep feeds has not been investigated. A pilot study was conducted using 120 pregnant composite ewes, sourced from the Charles Sturt University commercial flock. The ewes were run in a 15-hectare paddock sown with wheat (Triticum aestivum cv. EGA Wedgetail) and subdivided into four sub-paddocks. Two sub-paddocks were allocated to the treatment group and two sub paddocks to the control (n=30 ewes/sub-paddock).Each sub-paddock had an automatic water trough and two feeders containing a commercial loose lick (Stockmins CLS, AusFarm Nutrition). The sub-paddocks allocated to the treatment groups had the COS supplement mixed with the loose lick to provide an estimated daily loose lick intake of COS100-600 milligrams per day (assuming five to 30 grams total supplement consumed per ewe/per day). Ewes were supplemented from five weeks prior to the commencement of lambing through to lamb marking(average lamb age was about four weeks). Ewe body weight was recorded at the start of the trial. Body weight was also recorded for ewes at lamb marking and weaning (lamb age about 13 weeks). Blood and faecal samples were collected from 15 ewes from each sub paddock at the commencement of the trial and from the same ewes at lamb marking and weaning.36 2021 Graham Centre Livestock Forum Milk samples were also collected from ewes that were milking at lamb marking and weaning.Lamb body weights were recorded at marking and weaning, and a sample of lambs (15 per sub-paddock)were randomly selected at each event for blood and faecal sampling. Immunity markers of serum IgG, IgM,IgA and sIgA, as well as the pro- and anti-inflammatory cytokines including interleukin (IL) 2, IL10, were determined by enzyme-linked immunosorbentassay (ELISA). Results The incorporation of COS in sheep feed did not compromise feed palatability, with the supplement intake of ewes similar between the treatment and control groups.There was no significant influence on weight gain in ewes or lambs when COS was included in the ration.Supplementation with COS did significantly increases erum IgM concentrations in lambs at marking, which implies that COS has the potential to improve lamb health.No significant effect was observed in the concentration of any other immune markers and cytokines in both ewes and lambs at marking and weaning. Further studies are needed to understand the nutritional significance of COSin sheep production and health.