Influence of energy and polymer-encapsulated methionine supplements on mohair growth and fibre diameter of Angora goats fed at maintenance

Abstract

We studied the fleece production of Angora wether goats provided with energy, to maintain liveweight, and polymer-encapsulated methionine while they were fed on poor quality roughage rations in early summer. Forty goats (mean fleece-free liveweight 28.5 kg) were randomly allotted to 5 treatments and housed individually for 12 weeks. The treatments were: control, fed to lose 5 kg liveweight; M, fed to maintain liveweight; and 3 maintenance rations with either 0.5, 1 or 2 g day-1 of polymer-encapsulated methionine. The basal ration was oaten chaff (56.8% digestible dry matter) and all maintenance- fed goats received a supplement of 150 g day- 1 gristed barley. Goats required an estimated 267 kJ ME kg-0.75 day-1 to maintain liveweight. Goats fed the control diet grew less mohair (P<0.05) with reduced mean fibre diameter (P< 0.05) than maintenance-fed goats (4.9 g day-1, 30.0 pm compared with 5.8 g day-1, 31.9 pm). For maintenance-fed animals, the addition of 1 g day- methionine (0.15% of dry matter intake) increased mohair growth by 0.8g day-1 (P<0.075). Feeding barley to prevent liveweight loss and feeding polymer-encapsulated methionine at maintenance is unlikely to result in economic responses in mohair production of goats grazing low quality summer pastures.