Effetti del pascolamento della sulla e/o della loiessa per 8 o 24 ore sul comportamento alimentare e sulla produzione lattiero-casearia di pecore Comisane

Abstract

This experiment aimed to examine the effects of the utilization of monocultures of ryegrass (R), sulla (S) or both of them (RS), and the prolongation of daily grazing from 8 h (8:00-16:00) to 24 h, evaluating behaviour, selectivity, intake and milk and cheese production of ewes at pasture. The experiment involved 42 Comisana ewes averaging 146±55 days in milk, divided into 6 homogeneous groups which, since 19th April for 42 days, continuously grazed under a stocking rate of 34 ewes/ha. Ewes involving in eating activity were higher in R and for 24-h grazing, in relation to lower intake rate. RS ewes reduced eating time and increased lying activity. During daytime, the eating gradually decreased in R and RS, whereas was constant in S; during night, eating was concentrated at sunset, especially in R. In RS, ewes showed higher selectivity for sulla than ryegrass. The pasture affected milk yield (563, 669 and 766 g/d for R, RS and S; P<0.001), superior for S ewes, in correspondence of their higher herbage intake (1126, 1210 and 1464 g/d of DM for R, RS and S; P<0.001). S milk was higher in casein (4.49, 4.54 and 4.72% for R, RS and S; P<0.05) and, as a consequence of higher protein intake of ewes, in urea (40.3, 46.5 and 51.2 mg/dl for R, RS and S; P<0.001). When grazing was extended to 24 h, herbage intake (1349 vs 1184 g/d of DM; P<0.001) and milk yield (725 vs 608 g/d; P<0.001) increased, whereas milk fat decreased (6.98 vs. 7.36%; P<0.05). S forage and 24-h grazing significantly improved BCS of ewes. Both sulla utilization and 24-h grazing induced in cheese a fat reduction and a total nitrogen increase, whereas cheese from sulla forage showed a more intense yellow colour. At triangle test, cheeses S8 and S24 were different (P<0.05). Results showed that sulla herbage may really constitute the exclusive forage source in diet of ewes and, when possible, the extension of daily grazing time more than 8 h is advantageous.