A. Muscio

Effect of parity on milk yield, composition, somatic cell count, renneting parameters and bacteria counts of Comisana ewes

Twenty-four Comisana ewes, with no history of mastitis, were included in this study, with eight ewes each in parities 1, 2 and 3. Groups were separately penned on straw litter and ewes were individually checked for yield, composition, renneting properties and bacteriological characteristics of milk from January, when separated from their lambs (50+/-3 days after lambing), to May. Samples with more than 3.5x10(5) somatic cells/ml were cultured for mastitis related pathogens. Milk yield was not significantly affected by parity. The P3 ewes had significantly higher milk protein, casein and fat contents compared to the P1 and P2 ewes. The P3 ewes also had improved renneting ability of milk as compared to the P1 ewes. Quality of milk decreased with lower lactations. The milk of P1 ewes had significantly greater amounts of mesophilic bacteria than the P2 and P3 ewes, as well as higher concentrations of psychrotrophs and total coliforms in their milk with respect to the P3 ewes. Somatic cell counts in milk and the prevalence of subclinical mastitis were not changed by parity, although mastitis infection set in progressively earlier as the number of lactations decreased. These results suggest that ewes in first or second lactation have a less favourable milk secretion status in relation to mastitis than ewes with a higher number of lactations. Milk yield and quality of younger ewes may be improved by offering feed rations that take into account this reduced capacity to mobilise body reserves. Also, most scrupulous control of sanitation of housing, equipment and personnel is necessary.

Flaxseed supplementation improves fatty acid profile of cow milk.

The objective of the study was to determine the effects of adding flaxseed or fish oil to the diet on the milk fatty acid profile of cows. The experiment was conducted in the summer of 2006 and involved 24 Friesian cows that were divided into 3 groups of 8 animals according to different type of fat supplementation: a traditional diet with no fat supplementation, a diet supplemented with whole flaxseed, and a diet supplemented with fish oil. Results suggested that whole flaxseed supplementation positively affects the milk fatty acid profile during summer. In particular, milk from cows receiving flaxseed supplementation showed a decrease in saturated fatty acid, an increase in monounsaturated fatty acid, and, together with the milk from fish oil-supplemented cows, an increase in polyunsaturated fatty acid content compared with milk from control cows. As expected, both fish oil and flaxseed supplementation increased the content of n-3 polyunsaturated fatty acids in milk fat. The increased dietary intake of C18:3 in flaxseed-supplemented cows resulted in increased levels of milk C18:1 trans-11 and increased conjugated linoleic acid C18:2 cis-9,trans-11 by Delta(9)-desaturase activity. Milk from flaxseed-supplemented cows together with the high conjugated linoleic acid content was characterized by low atherogenic and thrombogenic indices, suggesting that its use has less detrimental effects concerning the atherosclerosis and coronary thrombosis risk associated with the consumption of milk and dairy products. In conclusion, flaxseed supplementation improves composition and nutritional properties of milk from cows milked during times of high ambient temperature.

Effect of stocking density on ewes' milk yield, udder health and microenvironment.

Three groups of 12 lactating Comisana ewes were housed in separate rooms of the same building that contained straw-bedded pens with total areas of 12, 18 and 24 m2. The ewes were assigned to groups with different stocking densities: high (HSD, 1 m2/animal), medium (MSD, 1.5 m2/animal) or low (LSD, 2 m2/animal). The LSD treatment resulted in lower air concentrations of total microorganisms and coliform bacteria than the other two. Ewes in the LSD group gave greater yields of milk, total protein and fat than those in the other two groups. LSD treatment increased milk casein content and improved clotting time and clot firmness. LSD also resulted in ewes giving milk with lower somatic cell counts and smaller concentrations of mesophiles, psychrotrophs and faecal coliforms than MSD and HSD. Subclinical mastitis occurred in three ewes of the MSD groups and four ewes of the HSD group, while no cases were recorded in the LSD group. These results indicate that stocking density is a critical factor in dairy sheep housing and suggest that a space allocation < 2 m2/animal may adversely affect the performance and health of the lactating ewe.

Effect of forage to concentrate ratio on growth performance, and on carcass and meat quality of Podolian young bulls

The effect of forage to concentrate ratio: 60-40 [high concentrate group (HC) and 70-30 [low concentrate group (LC)] on growth, slaughtering performance and meat quality were evaluated in twenty organically farmed Podolian young bulls. Meat quality characteristics were measured on three different muscles [Longissimus dorsi (LD), Semimembranosus (SM) Semitendinosus (ST)], vacuum-packaged and chilled stored at 2-4°C for 15 days. The animals in the HC group had higher weight gain than those in the LC group (P<0.05). Slaughter data were not influenced by ration composition. The higher forage to concentrate ratio produced an improvement in fatty acid composition of the three muscles, with a higher polyunsaturated to saturated ratio (P<0.001). Vitamin E and malondialdehyde (MDA) contents were not affected by the feeding treatment. Panel scores for tenderness and flavour (P<0.01) and Warner-Bratzler Shear force (P<0.001) were significantly affected by muscle, the LD muscle being the most tender and the richest in flavour but they not affected by dietary treatment.

Fatty acid composition of ewe milk as affected by solar radiation and high ambient temperature.

Forty lactating Comisana ewes were either exposed to or protected from solar radiation and fed either in the morning or afternoon during summer in a Mediterranean climate. Individual milk samples were taken on days 7, 21 and 42 of the study period to determine fatty acid composition by gas chromatography. Exposure to solar radiation resulted in higher proportions of short-chain and saturated fatty acids in milk, primarily because of increased contents of caproic, capric, lauric, myristic and stearic acids (by 3-18%), and decreased contents of oleic, linoleic and linolenic acids (by 2-9%). As a consequence, the long to short chain and the unsaturated to saturated fatty acid ratios were significantly higher by 4 and 13% respectively in the milk of the protected ewes compared with that of the exposed animals. Provision of shade also led to an increase in the 18:0+18:1 to 16:0 ratio, and to a decrease in the 12:0 + 14:0 + 16:0 fatty acid group, which are regarded as reliable indexes of the nutritional property of dietary fat in reducing cholesterol levels in human plasma. Feeding time had little impact on milk fat. Our findings suggest that high ambient temperature may markedly modify the lipid composition of ewe milk and that provision of shade, but not feeding management, can improve the milk fatty acid profile in dairy sheep raised in hot climates.

Influence of space allowance and housing conditions on the welfare, immune response and production performance of dairy ewes.

The experiment used 45 Comisana ewes, divided into 3 groups of 15. The aim was to determine the effects of two different stocking densities and two different housing conditions on welfare, and on production performance of dairy ewes. The stocking densities tested were: high stocking density (1 x 5 m2/ewe, HD group) and low stocking density (3 m2/ewe, LD group); the two housing conditions tested were: ewes housed indoors (LD group, 3 m2/ewe) and ewes allowed to use an outdoor area (LDP group, 3 m2/ewe divided into 1 x 5 m2/ewe indoors and 1 x 5 m2/ewe outdoors). At the beginning of the experiment, and then every 2 months, the cell-mediated immune status of sheep was evaluated. One month after the beginning of the experiment, and 20 d later, the ewes were injected with chicken egg albumin (OVA) to assess their humoural immune responses. Starting from the beginning of the experiment and then monthly, behavioural activities of ewes were monitored using 15-min scans. After lamb weaning, milk yield from individual ewes was measured and milk composition analysed weekly. Housing conditions (low density reared ewes indoors v. low density reared ewes with free access to an outdoor area) affected cell-mediated response, which was higher in LDP than in LD ewes. Concentrations of anti-OVA IgG were mainly influenced by space allowance, with higher antibody titres in LD than in HD ewes throughout the experiment. Both housing conditions and space allowance affected sheep behavioural activities: a greater proportion of LDP ewes displayed standing and drinking behaviours than LD ewes, and a greater proportion of LD ewes was observed walking than HD ewes. Ewes allowed access to the outdoor area had a higher protein content and lower somatic cell count in their milk, whereas reduced space allowance led to a reduction in milk yield and an increase in somatic cell count of milk. Results indicate that both increased space allowance and availability of outdoor area can improve the welfare and production performance of the lactating ewe.

Effects of litter management on airborne particulates in sheep houses and on the yield and quality of ewe milk

Forty early-lactating Comisana ewes, with no history of mastitis, were used in an 8-week experiment. The animals were divided into four groups of 10 and housed in four separate rooms in the same building. The treatments were: (1) fortnightly application of 0.5 kg granular bentonite per m2 of litter (BENT), (2) litter renewal after the first 4 weeks of the trial, without bentonite treatments (REN), (3) fortnightly litter treatments with bentonite+litter renewal (BENT+REN), and (4) neither bentonite treatments nor litter renewal (CTRL). The concentrations of gaseous pollutants and of airborne microorganisms and dust in the experimental rooms were measured twice weekly. Ewe milk yield was recorded daily. Individual milk samples were analyzed weekly for milk composition, coagulating properties, somatic cell concentration (SCC), and for bacteriological characteristics. The CTRL treatment resulted in higher concentrations of total and respirable dusts (P<0.001) than the three other treatments as well as in greater amounts of total microorganisms (P<0.01) and of yeast/moulds than the BENT and the BENT+REN treatments (P<0.05 and P<0.01, respectively). The CTRL ewes also gave lower yields of milk (P<0.01) and of protein and fat (P<0.001) than those of the three other groups. Litter management affected the hygienic quality of milk, CTRL ewes having higher somatic cell (P<0.01), and mesophilic and total coliform counts (P<0.001) in their milk than those of the three other groups, and greater amounts (P<0.05) of psychrotrophs and fecal coliforms than the BENT+REN animals. Our results suggest that litter management is critical for improving air quality in sheep houses and for optimizing the yield and the hygienic quality of ewe milk. Both litter renewal and treatment with bentonite may be effective in reducing air pollution and in sustaining ewe performance; however, the association of these procedures does not lead to further improvements of air and milk quality.

Effects of early maternal separation of lambs and rearing with minimal and maximal human contact on meat quality

The present study aims to assess the effect of gentling on behaviour and meat quality of lambs. Thirty-two Comisana lambs were divided into four groups of eight animals: ER (ewe reared), AR (artificially reared) and the corresponding gentled groups ERG and ARG. The provision of human contacts stimulated gentled subjects to explore, whereas the proportion of idling subjects was reduced (P<0.10). At increasing age the number of subjects contacting the person increased in the gentled groups (P<0.05). Lambs left with their dams showed higher warm and cold carcass yields compared to artificially reared animals, although animals benefiting from both maternal care and gentling, had the highest dressing percentage (P<0.05). Values of pH declined more rapidly in meat from gentled animals than from ungentled subjects (P<0.05), b* and h values were higher in ARG than in AR group (P<0.05), whereas Warner-Bratzler shear force and hardness tended to be lower in gentled lambs (P<0.15). We conclude that human-animal relationship can play an important role in affecting welfare, productive performances and meat quality of lambs, in particular when young subjects are prematurely separated from mothers.

Hypothalamic-pituitary-adrenal axis activation and immune regulation in heat-stressed sheep after supplementation with polyunsaturated fatty acids

The aim of this study was to assess the effects of supplementation with polyunsaturated fatty acids from different sources on immune regulation and hypothalamic-pituitary-adrenal (HPA) axis activation in heat-stressed sheep. The experiment was carried out during the summer 2012. Thirty-two Comisana ewes were divided into 4 groups (8 sheep/group): (1) supplemented with whole flaxseed (FS); (2) supplemented with Ascophyllum nodosum (AG); (3) supplemented with a combination of flaxseed and A. nodosum (FS+AG); and (4) control (C; no supplementation). On d 22 of the experiment, cortisol concentrations in sheep blood were measured after an injection of ACTH. Cellular immune response was evaluated by intradermic injection of phytohemagglutinin (PHA) at 0, 15, and 30 d of the trial. Humoral response to ovalbumin (OVA) was measured at 0, 15, and 30 d. At 0, 15, and 30 d of the experiment, blood samples were collected from each ewe to determine production of T-helper (Th)1 cytokines (IL-12 and IFN-γ), and Th2 cytokines (IL-10, IL-4, IL-13), and concentrations of heat shock proteins (HSP) 70 and 90. Ewes supplemented with flaxseed alone had greater cortisol concentrations and a longer-lasting cell-mediated immune response compared with ewes in the control and other groups. Anti-OVA IgG concentrations increased in all groups throughout the trial, even though ewes in the FS+AG group had the lowest anti-OVA IgG concentrations at 15 d. The level of IL-10 increased in all groups throughout the experiment; the FS+AG group had the lowest IL-13 concentration at 15 and 30 d. The concentration of HSP 70 increased in AG ewes at the end of the experiment and decreased in FS ewes, whereas that of HSP 90 increased in FS ewes compared with FS+AG ewes. Flaxseed supplementation was found to influence in vivo HPA activation in heat-stressed sheep, resulting in increased cortisol concentrations, probably to meet increased energy demand for thermoregulation. Flaxseed supplementation also supported Th1 response via a complex cross-talk between IL-10, IL-12, and IFN-γ production.

Group size effects on grazing behaviour and efficiency in sheep

Two grazing trials were conducted during early winter (January 1996) and spring (April 1996) to evaluate the effect of group size on grazing efficiency and behaviour of sheep. Three treatments were tested, large (LG), medium (MG) and small group size (SG), with 2 replicates for each treatment of 12, 9, and 6 ewes, respectively. Groups were homogeneous for age and weight. Paddock size furnished 10 m(2) per sheep per day. Group size did not affect grazing efficiency and herbage intake in the winter, but in the spring, when herbage mass was more plentiful, the ewes in the small groups grazed shorter, had a lower herbage intake and a less efficient use of forage. Consequently, the sheep in the small groups gained less weight than those in the large groups in spring. Neither group size nor seasonal changes in forage quantity or quality influenced sheep selectivity. These results suggest that the choice of a proper flock size at pasture can play a major role in optimizing grazing efficiency in sheep, especially when feeding is largely based on grazing, as generally occurs in countries of the Mediterranean basin in spring. Under the conditions of this study, our results indicate that a flock size of more than 6 sheep should be used for studies on sheep grazing behaviour.