Anna Nudda

Feeding strategies to design the fatty acid profile of sheep milk and cheese

The majority of sheep milk produced in the world is transformed into cheese. Feeding is a major factor affecting the quality of sheep milk and, therefore, of sheep cheese. Because fat is the main compound of cheese, this review gives an update on the effects of feeding and nutrition on milk fat content and deeply discusses feeding strategies aimed at increasing the levels of healthy fatty acids (FA), such as conjugated linoleic acid and omega-3 FA, in milk and cheese in the human diet. In addition, the use of alternative feed resources such as by-products, aromatic plants, and phenolic compounds in the sheep diet and their effects on milk and cheese FA composition are also discussed. Among feeding strategies, grazing and the use of supplements rich in oils seem to be the best and the cheapest strategies to improve the nutritional value of the fatty acid profile in sheep cheese.

The transfer of aflatoxin M1 in milk of ewes fed diet naturally contaminated by aflatoxins and effect of inclusion of dried yeast culture in the diet

An experiment was carried out to investigate 1) the transfer of aflatoxin M1 (AFM1) into the milk of dairy ewes fed diets naturally contaminated with aflatoxin B1 (AFB1); 2) the effect of the addition of dried yeast culture in the diet on this transfer; and 3) the alteration of enzymatic activities in the liver of ewes fed diets contaminated with AFB1. Twenty-four Sarda dairy ewes were divided in 4 groups and fed a concentrate mix containing 4 amounts of wheat meal naturally contaminated with aflatoxins. The diet of the control group had no wheat meal, whereas that of treated groups had low, medium, or high amounts of contaminated wheat, which corresponded to 1.13, 2.30, and 5.03 microg of AFB1/kg of feed, respectively. The experiment lasted 14 d. On d 8 to 14 from the beginning of the trial, 12 g/d of a commercial dried yeast product (DYP) of Kluyveromyces lactis was added to the diet of each ewe. The AFM1 concentration in individual milk samples and the blood serum metabolites were measured periodically. The presence of AFM1 was first detected in milk on d 1 of administration, and then its concentration increased and approached a steady-state condition on d 3 simultaneously in all treated groups. The AFM1 in milk at the steady-state condition, which was linearly related to the AFB1 intake, was 39.72, 50.38, and 79.29 ng/L in the low-aflatoxin, medium-aflatoxin, and high-aflatoxin groups, respectively. The AFM1 concentration in milk of the high-aflatoxin group was approximately 1.5-fold greater than the European Commission maximum tolerance level (50 ng/kg). The addition of DYP to the diet did not affect the AFM1 concentration in milk. After the withdrawal of the contaminated concentrate mix, the AFM1 mean concentrations decreased quickly and were no longer detected after 3 d in all treated groups. Daily milk yield and composition did not differ because of aflatoxin treatment. Blood serum parameters (creatinine, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, gamma glutamyl transferase, alkaline phosphatase, lactate dehydrogenase, cholesterol, protein, urea, calcium, and phosphorus) were not influenced by AFB1 intake. Therefore, the effect of DYP on certain blood parameters (gamma glutamyl transferase, urea, creatinine, and calcium) could not be attributed to amelioration of the aflatoxin-contaminated diet. In conclusion, diet contamination by AFB1 near the European Union tolerance level (0.005 mg/kg) in complete feed for dairy animals (e.g., high-aflatoxin group) can result in an AFM1 milk concentration higher than the European Commission maximum tolerance level. Transfer of aflatoxin from feed to milk was not affected by dietary addition of a commercial DYP.

Effects of lactation stage, parity, β-lactoglobulin genotype and milk SCC on whey protein composition in Sarda dairy ewes

Abstract In 90 Sarda dairy ewes the effects of lactation stage, parity, β-lactoglobulin genotypes, and somatic cell count (SCC) on the milk content of total protein (TP), casein (CN), whey protein (WP) and its fractions α-lactalbumin (ALA), β-lactoglob-ulin (BLG), serum albumin (SA), immunoglobulin (IG) and lactoferrin (LF) were analysed using a linear mixed model. Mean values of variables (g/l) were: TP (54.0), CN (43.0), WP (11.0), BLG (4.78), ALA (1.37), SA (0.61), IG (3.83) and LF (0.28). The lactation stage significantly affected all the variables analysed. TP, CN and WP concentrations tended to increase throughout lactation, with the increase of WP being more pronounced than the corresponding variation in CN. There was no definite trend in BLG content, whereas ALA concentration decreased as lactation progressed. The parity affected almost all variables studied. WP concentration differed significantly only between the second and fourth parity (10.45 vs 11.44 g/l). BLG and SA concentrations were significantly lower in the youngest ewes. The BLG genotype affected milk yield, but no effects were observed on the components of the milk. The SCC influenced almost all variables studied. The TP concentration was significantly higher in milk with SCC >1,000,000 (55.0 g/l) than in milk with lower SCC (53.4 g/l). This was mainly due to the increase of WP (12.52 and 10.24 g/l in milk with SCC above and below 1,000,000/ml respectively), especially in those WP fractions originating from blood.

Ultrasound technique for measuring mammary cistern size of dairy ewes.

Sarda ewes, ∼4·5 million animals producing 500 000 tonnes milk annually, are one of the most important breeds of dairy sheep in the Mediterranean area. Several studies (Casu & Labussiere, 1972; Labussiere et al . 1981; Gallego et al . 1983; Rebello de Andrade et al . 1989; Bencini, 1993) have shown that milk production is influenced by mammary gland size and cistern dimension. The size of the mammary cistern affects both milk secretion rate and milk emission kinetics during milking. Milk secretion rate is controlled at the mammary gland level mainly by a protein feedback inhibitor of lactation (FIL), which is produced by mammary epithelial cells and secreted together with milk into the alveoli (Wilde & Peaker, 1990). As the alveoli are the site of action of the FIL (Henderson & Peaker, 1984), the FIL affects the rate of secretion when the milk is stored in the secretory tissue, whereas it is inactive in the milk stored in the cistern. As a consequence, the action of the FIL should be less in animals with a greater cistern volume, because a large proportion of milk is stored in the mammary cistern and the time during which the milk is in contact with the alveoli is reduced. This hypothesis is supported by the finding that the milk production of cows (Dewhurst & Knight, 1992; Knight & Dewhurst, 1992, 1994) and sheep (Karam et al . 1971; Enne et al . 1972) with large cistern storage capacities was almost unaffected by changes in the frequency of milking. Cistern volume also affects milk emission kinetics and the proportion of stripped milk obtained at milking (Labussiere, 1988). Cisternal milk is immediately available for removal, whereas alveolar milk is available only after operation of the ejection reflex, necessary in dairy ewes for complete udder emptying (Bruckmaier et al . 1997). Therefore, in animals readily able to expel alveolar milk into the cistern before the whole cisternal milk fraction is removed (Pazzona et al . 1978; Bruckmaier et al . 1997), a larger cistern volume enables milking time to be reduced by eliminating or restricting the need for stripping. On the basis of the above considerations, the volume of the mammary gland cistern could be proposed as a selection objective to improve milk production and milking ability of dairy ewes. For this purpose, a quick, accurate and economic method for measuring it is needed. The ultrasound technique allows the internal structure of the mammary gland cistern to be observed clearly in sheep (Ruberte et al . 1994; Pulina et al . 1996; Bruckmaier et al . 1997), cows (Bruckmaier et al . 1994 b ) and goats (Bruckmaier et al . 1994 a ). Cistern size has been measured by ultrasound in dairy cows (Bruckmaier et al . 1994 b ) and sheep (Pulina & Nudda, 1996), where a positive correlation between milk yield and cistern area calculated from the ultrasound images of mammary glands was found. However, area estimation requires the use of expensive ultrasound equipment or of a digitizing tablet. In both cases, area measurement is difficult owing to the irregular shape of the cistern. The aim of this study was to test the use of linear measurements taken directly from ultrasound images to estimate cistern size in dairy ewes.

Effects of Ochratoxin A on Livestock Production

Ochratoxin A (OTA) contamination often causes large economic losses on livestock production. The intake of feed contaminated by OTA also represents a potential risk for animal health and a food safety issue due to the transfer of the toxin through the food chain to humans. The aim of this paper is to review the available literature on: (1) the frequency and degree of occurrence of OTA in different feedstuffs; (2) the toxicological effects of OTA intake on the performance of the main livestock (i.e., poultry, swine, cattle, goats and sheep); and (3) the transfer of OTA, or its metabolites, from animal feed into animal products such as milk, meat and eggs.

Milk composition and feeding in the Italian dairy sheep

Abstract Milk production represents a relevant quota of the energy consumption of the dairy ewe. Studies on relationships among level of production, milk composition and metabolic aspects are the first fundamental step in the development of a feeding system aimed at satisfying nutritive requirements of the animals. This paper reviews the knowledge about the milk composition of main Italian dairy sheep breeds, the relationship among secretion kinetics of milk and protein and productive level of animals, the algorithms used for estimating fat (6.5%) and protein (5.8%) corrected milk yield, the evolution over time of milk production during lactation and the relationships between feeding and milk composition.

Documentation of Fatty Acid Profiles in Lamb Meat and Lamb‐Based Infant Foods

UNLABELLED Lamb meat, when used in the weaning diet of children, is presumed to have a lower allergenicity than other forms of red meat. In children with atopic dermatitis and multiple food hypersensitivities, consumption of lamb meat has also resulted in significant clinical improvements in the severity of the eczematous lesions. Lamb meat is also of special interest in infant nutrition because it provides a somewhat unique fatty acid (FA) profile that mirrors what is thought to be optimal for neonatal growth and development. However, very little is known about how the processing of fresh meat (FM) into prepared infant foods influences its FA composition. In this study, we compared the FA profile of FM from suckling lambs with those of homogenized (HO) and lyophilized (LIO) baby foods prepared primarily with lamb meat. The results show that the content of total omega-3 polyunsaturated FAs was the highest in FM (more than 3-fold) compared to commercial baby food, due to largely higher contents of α-linolenic acid (1.5-fold higher), eicosapentaenoic acid (6-fold higher), and docosahexaenoic acid (10-fold higher). Furthermore, arachidonic acid was more than 6-fold higher in FM compared to LIO and HO. Results from this study suggest the possibility of enhancing the FA profile of commercial baby food based on meat by using lamb meat, but care should be taken during processing so that important FAs are not lost. PRACTICAL APPLICATION In this article, we have documented that meat from the suckling lamb is an interesting and potentially important source of omega-3-FAs, especially some of the long-chain polyunsaturated FAs (LC-PUFAs) that are essential for optimal neonatal growth and development. These results may have special implications to the infant food industry, in that products made using meat from suckling lambs may provide not only exceptional amounts of these FAs, but also other limiting essential nutrients such as iron. This may be especially important in regions of the world, such as Italy, where use of lamb meat as a weaning food is common during infancy.

Effect of extruded linseed supplementation on blood metabolic profile and milk performance of Saanen goats

This study assessed the effects of dietary supplementation with extruded linseed on milk yield and composition, milk fatty acid (FA) profile and renal and hepatic metabolism of grazing goats in mid-lactation. Forty Saanen goats were divided into two isoproductive groups: one group was fed the control diet (CON) composed of hay and pelleted concentrate and the other group was supplemented with additional 180 g/day of extruded linseed (LIN; dry matter basis), which supplied 70 g/day of fat per head for 9 weeks. Animals grazed on pasture for ∼3 h/day after the first of the 2 daily milkings. Milk samples were collected weekly and analyzed for fat, protein, lactose, milk urea nitrogen (MUN) and somatic cell count. Blood samples were collected every 2 weeks and analyzed for total bilirubin, creatinine, aspartate transaminase (AST), alanine transaminase (ALT), gamma glutamyl transpeptidase, alkaline phosphatase, total protein and urea nitrogen. Milk yield was higher in the LIN than in the CON group (2369 v. 2052 g/day). LIN group had higher milk fat (37.7 v. 33.4 g/kg) and protein (30.7 v. 29.1 g/kg) concentration and lower MUN (35.0 v. 43.3 mg/dl) than CON group. Goats fed LIN had greater proportions of 18:1 trans11, 18:2 cis9trans11 and total polyunsatured fatty acids n-3 in milk fat, because of higher 18:3n-3 and 20:5n-3 FA, and lower proportions of short- and medium-chain FAs than goats fed CON. All kidney and liver function biomarkers in serum did not differ between dietary groups, except for AST and ALT, which tended to differ. Extruded linseed supplementation to grazing mid-lactating goats for 2 months can enhance the milk performance and nutritional profile of milk lipids, without altering the general hepatic and renal metabolism.

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.

Non-nutritional factors affecting lactation persistency in dairy ewes: a review

Abstract Milk production is largely related to the shape of the lactation curve. Key elements of the lactation pattern are peak yield, which is the maximum daily yield reached during lactation, and lactation persistency, which is the medium rate of milk yield decrease after the lactation peak. The ideal lactation curve should have a reasonably high peak and a flat trend afterwards. A more persistent lactation is desirable because it is related to better animal health and reduction of feeding costs. Effective strategies to improve lactation persistency require a deep understanding of the main factors that affect this trait, including genetics, hormonal status and administration, udder morphology, seasonal changes, management, animal health (e.g. mastitis), stress and nutrition. This review covers the effects of non-nutritional factors on lactation persistency in dairy sheep.