Mauro Decandia

The use of polyethylene glycol to reduce the anti-nutritional effects of tannins in goats fed woody species

The effect of polyethylene glycol (PEG) on intake and digestibility in Sarda goats either fed in metabolic crates or browsing a Mediterranean scrubland, featured by tannin-rich species, was studied. In metabolic cages (Experiment 1) nine dry goats were fed ad libitum with foliage of lentisk (Pistacia lentiscus L.) supplemented with 200 g per day of a concentrate and either 0, 25 or 50 g per day of PEG. In the scrubland (Experiment 2), with lentisk as main species, 20 goats at the end of lactation, were supplemented with hay and concentrate, receiving 0 or 50 g per day of PEG. In both experiments the PEG did not affect the diet intake. The in vivo CP digestibility of the diet raised from 37% without PEG to 71% with 50 g of PEG in Experiment 1( P<0.05) and from 40 to 53% in Experiment 2 (P<0.01). In the latter experiment the PEG supplemented goats had a higher proportion of lentisk in the diet than the controls (P<0.05). The milk production and the milk urea content increased as a consequence of PEG supplementation. The PEG showed its capacity to neutralize the tannins allowing a better utilisation of tanniferous species. # 2000 Elsevier Science B.V. All rights reserved.

Excretion pattern of aflatoxin M1 in milk of goats fed a single dose of aflatoxin B1.

The feedstuffs used in dairy animals must be able to give consumers confidence about the wholesomeness of milk with regard to aflatoxin contamination. The aim of this study was to determine the excretion patterns of aflatoxin M(1) (AFM1) in the milk of dairy goats fed a single dose of pure aflatoxin B(1) (AFB1), which can occasionally occur if feeds are infected by hot-spot growth of molds that produce aflatoxins. Five dairy goats in midlactation were administered 0.8 mg of AFB1 orally. Individual milk samples were collected for 84 h after AFB1 dosage. Aflatoxin M(1) was found in milk in the highest concentration. In all goats, AFM1 was not detected in milk before AFB1 administration, but was detected in the first milking following AFB1 administration. The excretion pattern of AFM1 concentration in milk was very similar in all goats even if the values of the concentration differed between animals. The peak values for AFM1 concentration in milk was observed in milk collected during the milking at 3 and 6h. After the peak, the AFM1 in milk disappeared with a trend that fitted well a monoexponential decreasing function, and the toxin was not detected after 84 h. Only about 0.17% of the amount of AFB1 administered was detected as AFM1 in milk, and about 50% of this was excreted in the first liter of milk yielded after AFB1 intake. Correct procedures to prevent growth of molds, and consequent AFB1 contamination, on the feedstuffs for lactating goats represent the key to providing consumers a guarantee that milk is not contaminated by AFM1.

The effect of dietary iodine supplementation in dairy goats on milk production traits and milk iodine content

Dairy products offer an important source of iodine for humans, particularly infants and children. An adequate iodine content in the diet of lactating animals must guarantee a suitable milk iodine concentration. In this experiment, the effects of iodine supplementation of dairy goat diets on the iodine concentration, milk yield, and milk composition of goat milk were studied. Thirty crossbred dairy goats of the Sarda population were divided into 3 groups supplemented with 0 (control group), 0.45 (group 1), or 0.90 (group 2) mg of KI/d per goat. The dose of KI (76.5% of iodine) was dissolved in water and orally administered with a syringe every day for 10 wk. Mean milk iodine concentrations were 60.1 +/- 50.5, 78.8 +/- 55.4, and 130.2 +/- 62.0 microg/L (mean +/- SD) in the control group, group 1, and group 2, respectively. The extent of iodine enrichment in milk was approximately 31% in group 1 and 117% in group 2 compared with the control group. Milk yield was not influenced by KI supplementation and averaged 1,229, 1,227, and 1,179 g/d in groups 0, 1, and 2, respectively. Milk urea nitrogen concentration was significantly lower in the KI-supplemented groups (32 and 33 mg/dL in groups 1 and 2, respectively) than in the control group (37 mg/dL). Iodine supplementation of dairy goat diets can increase milk iodine content without adverse effects on milk production traits.

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.

Excretion of Aflatoxin M1 in milk of goats fed diet contaminated by Aflatoxin B1

Abstract An experiment was carried out to study the excretion of aflatoxin M1(AFM1) in milk of three goats fed a single dose (0.8mg/head) of pure aflatoxin B1 (AFB1). The values of AFM1 concentration excreted in milk was highly variable among goats, even if the pattern of excretion over time was very similar among the three animals. AFM1 was first detected at the milking performed 1h after the AFB1 administration. The highest values of AFM1 concentration in milk were reached 3 and 6h after the AFB1 intake. The trend of clearance of AFM1 in milk over time was expressed by a decreasing exponential equation. AFM1 concentration was below the EU maximum allowed level (50 ng/L) in milk collected 36 h after the AFB1 administration.

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.

Effect of corn and beet pulp based concentrate on ruminal parameters in wethers fed with fresh forage

Abstract Four wethers housed in individual pens and fitted with ruminal cannulae were grouped (two wethers per group) and fed fresh forage (Italian ryegrass, Lolium multiflorum) with either beet pulp (BP) or corn based concentrate (C) as supplements, using a crossover experimental design. The experiment was carried out during two experimental periods: the growing phase (early spring, G) and the reproductive phase (late spring, R) of the ryegrass. The diet of each animal was changed as the grass moved from the vegetative phase to the reproductive phase. The intake, the chemical composition of the diet and ruminal parameters such as pH, ammonia and volatile fatty acid were determined. Total dry matter intake (DMI) decreased from early to late spring (1081 vs 767 g/d; P<0.0001). Herbage DMI in particular decreased more (811 vs 543 g/d; P<0.05) than concentrate DMI (271 vs 224 g/d; P<0.054). There were marked differences in the chemical composition of the diet in wethers fed with the forage from early or late spring. This was because of changes in the characteristics of the forage. In detail, DM, NDF and ADF increased from early to late spring while CP, and EE decreased (P<0.05). Ruminal pH was lower in G than in R (6.24 vs 6.57, P<0.05). The concentrate used had no effect on the pH value. The ammonia concentration in the rumen fluid decreased from early to late spring (10.79 vs 6.68 mg/100 ml, P<0.05) and it was not influenced by the source of carbohydrates from the concentrate. VFA rumen fluid concentration increased (P<0.05) after feeding and decreased before the second meal. In the rumen fluid, the maximum total VFA concentration and the lowest pH were observed 2 h after the morning meal. Acetate and butyrate concentrations in the rumen fluid were influenced by the period (P<0.05) but not by the concentrate source. By contrast, the concentrate source significantly influenced the rumen fermentation patterns of propionate and VFA ratios, with higher propionic acid and lower acetate to propionate ratios in C than BP. This highlights the importance of the carbohydrate source in supplements for pasture based rations which varied according to the proportion of beet pulp and corn in the ingested diet.