The objective of the study was to investigate the effect of season on the fatty acid and terpene composition in ewe milk. A total of 760 samples of bulk sheep milk were collected during winter (147 samples), spring (314 samples) and summer (299 samples) of 2011, from 90 commercial farms of dairy sheep from the prefecture of Grevena, Greece. Regarding fatty acid composition, summer samples had higher concentrations of α-linolenic acid, cis-9, trans 11- CLA, trans-11, C18 : 1 and PUFAs but lower content of saturated fatty acids particularly C12 : 0, C14 : 0 and C16 : 0. The winter milk had the lowest content of terpenes, in particular sesquiterpenes, compared to spring and summer milk. The terpene profile of milk samples, in all three seasons, revealed the presence of monoterpenes: a-pinene, b-pinene and D-limonene, especially with a higher frequency of appearance in summer. The most common and abundant sesquiterpenes found in milk samples were β-caryophyllene and α-caryophyllene with a higher frequency of appearance in summer. In conclusion, the available pastures in semi-extensive farming systems can contribute to the production of high quality milk.

This study was undertaken to assess the effect of somatic cell count in ewe milk on i) composition and hygienic traits; ii) plasmin, cathepsin and elastase activities; iii) leukocyte differential count; iv) renneting parameters. Individual ewe milk samples were grouped according to somatic cell count (SCC) into five classes: SC300 (<300 000 cells/ml), SC500 (from 301 000 to 500 000 cells/ml), SC1000 (from 501 000 to 1 000 000 cells/ml), SC2000 (from 1 001 000 to 2 000 000 cells/ml) and SC>2000 (>2 001 000 cells/ml). Individual milk samples were analysed for pH, chemical composition, microbial features, indigenous proteolytic enzymes, differential leukocyte population, and renneting parameters. Milk yield, lactose, protein, non casein nitrogen, microbial features were affected by SCC level. Plasmin and elastase activities were the highest in samples with more than 1 000 000 cells/ml; plasmin had intermediate values in samples with 300 000 to 1 000 000 cells/ml and the lowest in samples with less than 300 000 cells/ml of milk. Cathepsin D showed significantly lower values in SC300 and SC1000 classes than in SC500, SC2000 and SC>2000 classes. The highest percentages of lymphocyte were found in samples with less than 1 000 000 cells/ml, while the highest levels of polymorphonuclear leukocyte were found in samples with more than 1 000 000 cells/ml of milk. Longer clotting time was found in SC>2000 samples, while reduced clot firmness was observed in SC500 and SC>2000 samples. Results on milk yield and on compositional parameters evidenced an impairment of udder efficiency in ewe milk samples starting from 300 000 cells/ml. Plasmin activity in milk can be considered as a marker of the synthetic and secreting ability of the mammary gland; furthermore plasmin and elastase were consistent with the health status of the udder. Finally cathepsin D played a role in the worsening of renneting properties of ewe milk.

This study was undertaken to compare flow cytometry (FC) and direct microscopic leucocyte count (MDLC) for the differentiation of macrophages, lymphocytes and polymorphonuclear leucocyte (PMN) and to evaluate leucocyte distribution in ewe milk with low and high somatic cell count (SCC). Milk samples were grouped for somatic cell count in low SCC (LSCC) when the content was lower than 5·00×105/ml and high SCC (HSCC) when the content was higher than 1·00×106/ml. No differences were found between the two methods tested suggesting that FC could be used as a routine test for rapid discrimination of leucocytes. Percentages of lymphocytes in ewe milk were higher in LSCC (50%) than in HSCC (39%) and count ranged from 273·91±56·62×103cells/ml (LSCC) to 308·90±46·15×103cells/ml (HSCC). PMN number was lower in LSCC than in HSCC (248·83±46·87×103cells/ml v. 444·38±58·62×103cells/ml); accordingly the percentage was lower in LSCC (40%) than in HSCC (57%). No differences were found for macrophages which were 36·36±5·51×103cells/ml and 39·32±6·83×103cells/ml in LSCC and HSCC, respectively. Lymphocytes in ewe milk did not vary with increased number of somatic cells and were the predominant cell type in LSCC. PMN represented the main population detected in HSCC and the correlation with SCC evidenced that this leucocyte class could be useful in differentiating ewe milk cell count, being strictly responsible for the SCC increase.

Twenty pregnant Comisana ewes were divided into two groups of 10. One group was allowed to graze a vetch pasture (grass). The second group of animals was housed collectively in a pen and was given hay and concentrates (concentrate). After lambing, all the ewes were allowed to stay with the respective lambs between 18:00 h and 07:00 h of the following day in two different pens. Therefore all the lambs were raised exclusively on maternal milk. The lambs were slaughtered at 38 days of age. Milk and lamb meat (longissimus dorsi muscle) fatty acids were analysed. Ewes on grass produced milk with a lower (P < 0·001) proportion of saturated fatty acids and with a higher proportion of both monounsaturated (P < 0·05) and polyunsaturated fatty acids (P < 0·01) than ewes given concentrates. Trans-vaccenic acid was significantly higher (P < 0·001) in milk from grass-fed animals compared with ewes given concentrates. Linoleic acid (C18: 2 n-6) tended to be higher (P = 0·06) in milk from ewes on concentrates while linolenic acid (C18: 3 n-3) was significantly higher (P < 0·001) in milk from animals grazing pasture. Conjugated linoleic acid (cis-9, trans-11 C18: 2) was almost double in milk from grass-fed ewes compared with animals given concentrates (P < 0·001). Regarding lamb tissue, trans-vaccenic acid (C18: 1 trans-11) was higher (P = 0·01) in the fat from lambs raised by grazing ewes. Linoleic acid (C18: 2 n-6) was at higher concentration (P < 0·001) in the fat from lambs raised by ewes given concentrates. Linolenic acid (C18: 3 n-3) was increased three-fold (P < 0·001) in the fat of lambs from the grass group compared with lambs suckled by ewes given concentrates. The isomer cis-9, trans-11 of conjugated linoleic acid was present at double concentration (P < 0·001) in the fat from animals raised by grazing ewes. Eicosapentaenoic (C20: 5 n-3; EPA) and docosaesaenoic (C22: 6 n-3; DHA) acids were higher (respectively P < 0·001 and P = 0·01) in the intramuscular fat from lambs from the grass group compared with animals from the concentrate group. The n-6/n-3 ratio was lower (P < 0·001) in the meat from lambs raised by grazing ewes. Overall this trial showed that ewe feeding system strongly affects intramuscular fatty acids even in lambs raised exclusively on maternal milk.

The study was carried out in a commercial flock on 286 Churra breed ewes (566 half-udders) assigned to three lots depending on the type of antibiotic dry therapy received in the lactation previous to the one studied. One-hundred-and-four ewes were given complete therapy in all udders, 103 received selective therapy of infected half-udders, and 79 received no therapy at all. Half-udders of all animals were sampled for bacteriological study at ≤72 h (lambing), 60 d, 120 d, and 155 d (drying-off) post partum. Dry therapy, parity number, lactation stage and therapy×parity interaction contributed significantly to variation in intramammary infection prevalence. Antibiotic dry therapy had the most significant effect. Prevalence during the whole of the subsequent lactation was significantly lower in lots receiving complete (18·8%) and selective (15·6%) dry therapy than in the untreated control lot (48·3%). Coagulase-negative staphylococci and streptococci (in particular Streptococcus agalactiae) were the organisms most significantly affected by dry therapy. In untreated ewes, prevalence increased noticeably from the 2nd to the 6th and subsequent lactations, but no significant changes were observed in the treated lots. Milk yield in the dry treated lots was 6·9% higher that in the untreated one. It was concluded that complete and selective treatments of ewes at drying-off were efficient and comparable methods of reducing the intramammary infection prevalence, improving bacteriological quality of milk, and increasing milk yield.

The interpretation of the results of feeding trials with lactating ewes and their sucking lambs can be improved considerably when milk energy production is known. The determination of gross energy (GE) however is time consuming and expensive. Therefore an equation to predict GE from milk constituents would be helpful.

Using multiple regression analysis a GE-prediction equation was derived with milk samples mainly from crossbred ewes. The concentrations of milk constituents were determined by infrared spectrometry (calibrated with cow milk). Fat concentration ranged between 43·8 and 125·0 g/kg, protein concentration between 32·4 and 53·1 g/kg and lactose concentration between 38·9 and 52·9 g/kg. GE (adiabatic bomb calorimetry) of the samples under consideration ranged between 3500 to 6800 kj/kg.

The following equation, including fat (f), protein (p) and lactose (I), is recommended and predicts GE as kj/kg fresh milk using constituents in g/kg fresh milk:

GE = 41·94 × f + 15·85 × p + 21·41 ×l (residual s.d. = 92, adj.R2 = 0·98).

This equation has, in the GE range 4500 kj to 6000 kj, an almost constant confidence interval with an average of ±25 kJ and an almost constant prediction interval, with an average of ±87 kJ. In the period until weaning it would appear justified to use the derived equation regardless of stage of lactation. The equation is valid for milk samples from sheep breeds with relatively high fat and low protein contents and where milk constituents have been determined by cow milk calibrated infrared spectrometry.