Effects of ewes grazing sulla or ryegrass pasture for different daily durations on forage intake, milk production and fatty acid composition of cheese

Abstract

Sulla (Sulla coronarium L.) forage is valued for its positive impact on ruminant production, in part due to its moderate content of condensed tannin (CT). The duration of daily grazing is a factor affecting the feed intake and milk production of ewes. In this study, the effects of grazing sulla pasture compared with annual ryegrass, and the extension of grazing from 8 to 22 h/day, were evaluated with regard to ewe forage intake and milk production, as well as the physicochemical properties and fatty acid (FA) composition of cheese. During 42 days in the spring, 28 ewes of the Comisana breed were divided into four groups (S8, S22, R8 and R22) that grazed sulla (S) or ryegrass (R) for 8 (0800 to 1600 h) or 22 h/day, and received no feeding supplement. In six cheese-making sessions, cheeses were manufactured from the 48 h bulk milk of each group. Compared with ewes grazing ryegrass, those grazing sulla had higher dry matter (DM) intake, intake rate and milk yield, and produced milk that was lower in fat and higher in casein. Ewes grazing for 22 h spent more time eating, which reduced the intake rate, increased DM and nutrient intake and milk yield, and reduced milk fat. Due to the ability of CT to inhibit the complete ruminal biohydrogenation of polyunsaturated fatty acids (PUFA), the FA composition of sulla cheese was more beneficial for consumer health compared with ryegrass cheese, having lower levels of saturated fatty acids and higher levels of PUFA and n-3 FA. The FA profile of S8 cheese was better than that of S22 cheese, as it was higher in branched-chain FA, monounsaturated FA, PUFA, rumenic acid (c9,t11-C18:2), and had a greater health-promoting index. The effect of short grazing time on sulla was attributed to major inhibition of PUFA biohydrogenating ruminal bacteria, presumably stimulated by the higher accumulation of sulla CT in the rumen, which is related to a higher intake rate over a shorter eating time. Thus, grazing sulla improved the performance of ewes, thereby increasing, especially with short grazing time, the nutritional properties of cheese fat.

Fatty acids, health indices and sensory properties of Ricotta cheese from sheep fed three different diets

“…While the P diet was lower in overall fat intake with less n‐6 FAs than the other two diets, the n‐3 FA content was not as high as that of the L‐group, resulting in a lower ratio. The presence of green grass and primarily Sulla on the pasture contributed to the n‐3 FA intake, as supported by previous work showing similar effects on raw milk and cheese (Bonanno et al ). Thus, although the L‐group had a high n‐6 FA content, the ratio for this group was the most favourable.…”

“…Regarding the P‐group, the Ricotta had the lowest SFA content because of the generally lower fat content, the lower energy intake of the grazing animals and the presence of Sulla in the pasture. Sulla is known to have a beneficial effect on the FA profile of milk and dairy products by lowering the SFA content, increasing the UFA level and improving the n‐3/n‐6 ratio (Bonanno et al ). It could be argued that further improvement of the pasture or a more suitable composition of grazing area would have resulted in an even better FA profile for the P‐group (Mierlita et al ).…”

Effect of refrigerated storage on microbiological, chemical and sensory characteristics of a ewes’ raw milk stretched cheese

“…Overall, the VdB cheese fatty acids composition is similar with those reported by Todaro et al (2014) for VdB cheeses produced in spring when ewes are fed with green forage, so these cheeses maintains some beneficial properties for human health, which a good level of PUFA among which rumenic acid (C18:2 c9 t11), and its precursor vaccenic acid (C18:1 t11). In this regard, the levels of rumenic acid, the more abundant among the CLA isomers, known for its anti-cancer and anti-atherogenic effects (Parodi, 2009), were comparable to those reported by Bonanno et al (2016) and Nudda, McGuire, Battacone, and Pulina (2005) for sheep cheeses produced by milk from grazing ewes in the same seasonal period. Table 3 reports the changes in sensory scores attributed to the cheese descriptors registered over time.…”

Nutritional Indices for Assessing Fatty Acids: A Mini-Review

“…The HPI is the inverse of the IA. It is currently mainly used in research on dairy products such as milk [ 92 , 93 , 94 ] and cheese [ 57 , 94 , 95 ]. Detailed information about the literature related to the HPI is provided in Table 6 .…”