Giovanni Molle

Models for estimating feed intake in small ruminants

This review deals with the most relevant limits and developments of the modeling of intake of sheep and goats reared intensively and extensively. Because small ruminants are normally fed ad libitum, voluntary feed intake is crucial in feeding tactics and strategies aimed at optimal animal production. The effects of genetic, neuroendocrine, hormonal, feed and environmental factors on voluntary feed intake were discussed. Then, several mathematical models to estimate dry matter intake (DMI) were examined, with emphasis on empirical models for sheep and goats in intensive farm systems or in extensive areas under pasture or rangeland conditions. A sensitivity analysis of four models of prediction of DMI in housed lactating dairy sheep and meat sheep breeds was also presented. This work evidenced a large variability in the approaches used and in the variables considered for housed sheep and goats. Regarding the estimation of feed intake for grazing sheep and browsing goats, the accuracy of estimates based on empirical models developed so far is very low when applied out of the boundaries of the studied system. Feeding experiments indoors and outdoors remain fundamental for a better modeling and understanding of the interactions between feeds and small ruminants. However, there is a need for biological and theoretical frameworks in which these experiments should be carried out, so that appropriate empirical or mechanistic equations to predict DMI could be developed.

Effects of different fat-enriched concentrates on fatty acid profile of cheese from grazing dairy sheep

References A trial on different fatty acid supplementation was run in grazing dairy sheep. Forty-eight lactating Sarda ewes were randomly allocated to four homogeneous groups: PAS, control group grazing for 22h/d without supplementation; NOF, group supplemented with a cereal based non-fat enriched concentrate; C182, group supplemented with a concentrate rich in sunflower seeds; and C183, group supplemented with a concentrate rich in linseeds. The results showed that the concentrates, based on oilseeds from both sunflower and linseed sources determined high C18:1 t11 and CLA c9 t11 cheese fat content. Moreover linseeds supplementation improved the concentration in the cheese of other beneficial fatty acids such as LN and PUFAω3.

Role of sensorial perceptions in feed selection and intake by domestic herbivores

Abstract Sensorial perceptions play an important role in feed selection and intake by herbivores. Much research has been carried out to study the sensorial perceptions evoked by forages and their effects on intake and feed selection. Certain specific compounds are clearly able to evoke positive or negative sensorial perceptions when forages are eaten. This might lead to the development of plant extracts and aromas that might be used to improve the intake of unpalatable feeds. In the case of concentrates, the little research available seems to support an important role of the interaction between sensorial perceptions and post-ingestive effects when simple unmixed concentrates are supplied. It is not clear to what extent these effects are important when compound concentrates are offered. Despite these advances, it appears that most of the research carried out so far has been exploratory and observational. More research is needed to better understand the mechanisms underlying feed palatability before it can be included in intake prediction models.

Effect of species, cultivar and phenological stage of different forage legumes on herbage fatty acid composition

Abstract An experiment was conducted to evaluate the effects of species, cultivar, and phenological stage, on the concentration of fatty acid composition in different forages legumes. Four species and eight cultivars Vicia sativa L. (VS cv. Jose JO, and Nikian NI), Vicia Villosa Roth (VV cv.Haiymaker HA, and Hungivillosa HU) Trifolium incarnatum L. (TI cv. Viterbo VI, and Contea CO), and Trifolium alexandrinum L. (TAX cv Marmilla MA and Sacromonte SA) were compared. Overall the main factors which influence fatty acids (FA) profile appear to be forage species and phenological stage but we need to consider the numerous interaction with these factors; besides the second important FA (C16:0) did not change between different phenological stages whereas linoleic acid increases (about 50% P<0.01) and linolenic acid decreases (about 10% P<0.01) from vegetative to reproductive stage. We observe also a worsening effect (P<0.05) on unsaturated/saturated (UNSAT/SAT) ratio from vegetative to reproductive stage. In conclusion these studies demonstrate a significant genetic component to the level and pattern of fatty acid concentration as well as a key role of the association between phenological stage and cultivars which modulated the amplitude and the trend of fatty acid pattern.

Re-visiting the nutrition of dairy sheep grazing Mediterranean pastures

Abstract In the light of recent findings in sheep nutrition and behaviour, the diets of grazing dairy sheep should be based on forages encompassing a variety of complementary nutritional values and containing moderate levels of complementary plant secondary metabolites, until recently regarded as “anti-nutritional”. In lactating sheep, pastures of tannin-containing legumes like sulla (Hedysarum coronarium) and chicory (Cichorium intybus) can be integrated with annual grasses for establishing sustainable artificial pastures under rainfed conditions. Diets based on these forages, while ensuring high milking performance, can mitigate the unbalance of CP to energy ratio of grazing sheep. By grazing sulla and annual or Italian ryegrass (50:50 by area) as spatially conterminal monocultures or in timely sequence (complementary grazing) sheep eat more and perform better than by grazing the ryegrass pasture only. Concentrate supplementation of lactating sheep should be preferably based on fibrous sources (soyhulls or beet pulps), particularly from mid-lactation onwards and when supplementation levels are high. Milk urea concentration is confirmedly a useful monitoring tool to balance protein nutrition and curb the waste of N at animal and system level.

A survey on the milk fatty acid composition of forty dairy sheep flocks in Sardinia

Abstract A survey was carried out to monitor milk fatty acid (FA) composition during two years (2003 and 2004) on forty dairy sheep flocks, fed pasture based rations, in 5 macro pedoclimatic areas of Sardinia, featured by different i) soil type, (granitic, G; basaltic, B and alluvial, A) ii) average annual rainfall (low, L, 500-600 mm/year; high, H, 600-800 mm/year). Milk FA profile was strongly influenced by year. In particular milk linolenic acid (LN), CLA (conjugated linoeic acid) and PUFA (polyunsaturated fatty acids) levels increased (by 25, 30 and 14%, respectively, P<0.01) whereas the atherogenicity index (AI) decreased (by 8%, P<0.01) in all areas in 2004 as compared with 2003. Pedoclimatic area affected milk fatty acid composition (P<0.01). In both years milk from AL farms showed the highest levels of LN, CLA and PUFA. AI was lower in BH and GH in year 2003 and in BH, AH and GL in 2004.