Effect of weaning system on commercial milk production and lamb growth of East Friesian dairy sheep

East Friesian crossbred ewes (n = 99) and their lambs (n = 232) were used to study the effects of three weaning systems on milk production and lamb growth. Prior to parturition, a ewe and her lambs were assigned to one of the following three treatments for the first 28 +/- 3 d of lactation: 1) ewes weaned from their lambs at 24 h postpartum, ewes machine milked twice daily, and their lambs raised artificially (DY1); or 2) beginning 24 h postpartum, ewes separated from their lambs for 15 h during the evening, ewes machine milked once daily in the morning, and their lambs allowed to suckle for 9 h during the day (MIX); or 3) ewes not machine milked and exclusively suckled by their lambs (DY30). After the treatment period, lambs were weaned from MIX and DY30 ewes, and all three groups were machine milked twice daily. Daily commercial milk yield and milk composition were recorded weekly or twice monthly, and lambs were weighed at weaning or at 28 d and at approximately 120 d of age. Average lactation length (suckling + milking period) was 183 +/- 5 d and was similar among weaning systems. Differences among weaning systems for milk yield, milk fat and protein percentages, and somatic cell count were highly significant prior to and around weaning, and became nonsignificant by 6 wk in lactation. Total commercial milk production was greatest for DY1 and MIX ewes (261 +/- 10 and 236 +/- 10 kg/ewe, respectively) and least for DY30 ewes (172 +/- 10 kg/ewe). Daily gain of lambs to 30 d and weight at 30 d were similar regardless of weaning system; however, by 120 d, DY30 lambs tended to be heaviest, MIX lambs intermediate, and DY1 lambs lightest (47.3 +/- 1.6, 45.9 +/- 1.8, and 43.7 +/- 1.2 kg, respectively). Overall financial returns for milk and lamb sales were greatest for the MIX system because of the increase in marketable milk during the first 30 d of lactation compared with the DY30 system and because of acceptable 120-d lamb weights without the expenses of artificial rearing compared with the DY1 system. A mixed system of suckling and milking during early lactation appears to be a valuable management tool for dairy sheep production.     

Influence of Electrical Stimulation, Cooling Rates and Aging on the Shear Force Values of Chilled Lamb

An investigation using high voltage (800 VRMS, 1140 V peak at 14.3 Hz) electrical stimulation (ES) showed that lambs should be stimulated within 30 min of slaughter for 60–120 sec for maximum effect on Warner-Bratzler shear force values. Shear force values of lamb muscles chilled at different rates were significantly (P<0.001) reduced by ES, compared with nonstimulated controls. However, aging at temperatures between 0° and 9°C, for only 2–3 days, educed shear force values of nonstimulated lamb subjected to moderate chilling rates to those of ES samples at 1 day postmortem. Increasing aging temperature significantly (P<0.001) increased aging rate but duration of aging had the greater effect.     

Influence of level of barley supplementation on plasma carotenoid content and fat spectrocolorimetric characteristics in lambs fed a carotenoid-rich diet

This study investigated changes in plasma carotenoid concentration and fat reflectance spectrum characteristics and color in lambs fed a carotenoid-rich diet with low-level (L, 100 g/lamb/day) or high-level (H, 400 g/lamb/day) of barley supplementation for 75 days before slaughter. Each treatment used 24 Romane male lambs that were individually penned indoors. Plasma carotenoid concentration at slaughter was 16% lower in H lambs than in L lambs. H lambs had heavier and fatter carcasses than L lambs. Yellowness and redness of perirenal fat were slightly lower in H lambs than in L lambs. The absolute value of the mean integral (AVMI) calculated from the reflectance spectrum of the fat in the 450–510 nm band was not affected by the treatment. Yellowness, chroma and AVMI of subcutaneous fat were not affected by the treatment but decreased with initial animal's liveweight.     

Fatty acid composition and cholesterol content of muscles as related to genotype and vitamin E treatment in crossbred lambs

Various factors (weight, sex, diet and breed) influence meat lamb fatty acid composition. The present study was undertaken to evaluate the lipid profile in two different lamb types. Sixty crossbred lambs (Ile de France×Pagliarola and Gentile di Puglia×Sopravissana) were used to determine cholesterol, lipid content and fatty acid profile of Longissimus dorsi, Semimembranosus and Gluteobiceps muscles. Moreover, the effect of vitamin E treatment in vivo on propensity of the lamb meat to lipoperoxidation was assessed. In both crossbreeds total muscle lipids ranged between 2.4 and 4.0 mg/100 g. In the Ile de France×Pagliarola lambs a lower percentage of saturated fatty acids and a low atherogenic index were found. The vitamin E treatment reduced significantly the lipoperoxidation, without difference between the two crossbreeds.     

Fatty acid composition and sensory characteristics of lamb carcasses from Britain and Spain

Fatty acid composition of intramuscular fat in M. Longissimus was measured in four groups of lambs representing two Spanish breeds: Rasa Aragonesa (RA) and Merino (ME) and two British lamb types: the Welsh Mountain breed (WM), whose carcasses were purchased in Spain and typical early lambs (EL) purchased in Britain. The lambs grown in Spain were concentrate fed and slaughtered at a lighter weight and lower age than those grown in Britain. The British lamb carcasses purchased in Spain were of a similar weight to the Spanish lambs but were lighter than the lamb carcasses purchased in Britain. The British lambs were grass fed. Relationships between fatty acid (FA) composition and sensory attributes were examined following sensory testing of all lambs by both British and Spanish taste panels. The production system was shown to be more important than breed in determining FA composition. British lambs had higher percentages, within total fatty acids, of 18:0, 18:3 (n-3) and long chain polyunsaturated n-3 FA and lower percentages of 18:2 (n-6) and long chain polyunsaturated n-6 FA than Spanish lambs. These differences were due to the different feeding systems used. The amounts of these FA in muscle (mg/100 g) were also different between the British and Spanish groups, not only because the British lambs had more total fat. For both taste panels, odour and flavour intensity were positively correlated with the amounts and percentages of 18:0 and 18:3 and negatively correlated with those of 18:2. This was explained by the fact that both panels gave higher odour and flavour intensity scores to the grass-fed British lamb with high 18:3 levels and lower scores to the concentrate-fed Spanish lamb with high 18:2 levels. However, 18:0 and 18:3 were positively correlated with flavour quality and overall appraisal for the British panel and negatively for the Spanish panel. Conversely, 18:2 was a positive contributor to flavour and overall preference for the Spanish panel and was negative for the British panel. The results show that the production system affects muscle fatty acid composition and the flavour of lamb. However, people's preference is determined to a large extent by their past experience.     

Effects of finishing period length with vitamin E supplementation and alfalfa grazing on carcass color and the evolution of meat color and the lipid oxidation of light lambs

Indoor-kept concentrate-fed light lambs (n = 54) were supplemented with 500 mg of dl-α-tocopheryl acetate/kg concentrate for 0, 10, 20 and 30 d before slaughtering at 22–24 kg BW. Simultaneously, 8 lambs with their dams were alfalfa-grazed and the lambs were slaughtered at the same weight. The age at slaughter and carcass characteristics were more affected by grazing than by supplementation with α-tocopherol. The grazing lambs had similar α-tocopherol levels to the lambs fed concentrate with dl-α-tocopheryl acetate for 10 days before slaughter. The length of the feeding period affected the evolution of the color, delaying the blooming and discoloration of the meat. Feeding lambs α-tocopherol enriched concentrate during the last 10 days of life or grazing them on alfalfa drastically diminished the lipid oxidation of the meat. Alfalfa grazing is a feasible alternative to increase light lamb meat shelf life without using additives.     

Acceleration of Tenderization/Inhibition of Warmed-Over Flavor by Calcium Chloride-Antioxidant Infusion into Lamb Carcasses

Infusion of 0.3M calcium chloride plus 1% sodium ascorbate or 0.25% maltol into freshly slaughtered lambs resulted in acceleration of postmortem tenderization through activation of calcium dependent proteases, inhibition of lipid oxidation and retardation of warmed-over flavor on ground cooked patties from their meat. After storage 2 days at 4°C, patties from lamb carcasses treated with antioxidants retained more desirable flavor characteristics (meaty and musty/herby) of lamb, and had less off-flavor (painty and cardboardy) intensities.     

A cohort study of the associations between udder conformation, milk somatic cell count, and lamb weight in suckler ewes

A cohort study of 67 suckler ewes from 1 farm was carried out from January to May 2010 to investigate associations between udder conformation, udder half milk somatic cell count (SCC), and lamb weight. Ewes and lambs were observed at lambing. Ewe health and teat condition and lamb health and weight were recorded on 4 to 5 further occasions at 14-d intervals. At each observation, a milk sample was collected from each udder half for somatic cell counting. Two weeks after lambing, ewe udder conformation and teat placement were scored. Low lamb weight was associated with ewe SCC >400,000 cells/mL (-0.73kg), a new teat lesion 14 d previously (-0.91kg), suboptimal teat position (-1.38kg), rearing in a multiple litter (-1.45kg), presence of diarrhea at the examination (-1.19kg), and rearing by a 9-yr-old ewe compared with a 6-yr-old ewe (-2.36kg). High lamb weight was associated with increasing lamb age (0.21kg/d), increasing birth weight (1.65kg/kg at birth), and increasing number of days the ewe was given supplementary feed before lambing (0.06kg/d). High udder half SCC was associated with pendulous udders (9.6% increase in SCC/cm of drop) and greater total cross-sectional area of the teats (7.2% increase of SCC/cm(2)). Low SCC were associated with a heavier mean litter weight (6.7% decrease in SCC/kg). Linear, quadratic, and cubic terms for days in lactation were also significant. We conclude that poor udder and teat conformation are associated with high levels of intramammary infection, as indicated by increased SCC and that both physical attributes of the udder and SCC are linked to lamb growth, suggesting that selection of suckler ewes with better udder and teat conformation would reduce intramammary infection and increase lamb growth rate.     

Assessment of commercial lamb meat quality by British and Spanish taste panels

Trained sensory panels in Britain and Spain assessed loin meat from commercial lambs purchased in Spain, which included Welsh lamb (imported from Britain) and two Spanish breeds (Merino and Rasa Aragonesa). The British panel also assessed British lamb purchased in local butcher shops and supermarkets. Sensory panels, in each country, received meat from the same lambs and used their local methods of cooking and assessment. Spanish panels used unstructured line scales to measure lamb odour intensity, tenderness, juiciness, lamb flavour intensity and two hedonic scales of flavour liking and overall liking. The British panel used 8 point category scales with the same attributes. Results from both panels in objective parameters were in agreement, hence showing that different trained sensory panels may arrive at the same conclusion. However, when panellists were allowed to make hedonic judgements (preference), the British panel preferred British lamb and the Spanish panel preferred Spanish lamb. This finding has important consequences for lamb producers who export their lambs and demonstrates that the underlying reasons for different preferences should be investigated. Production variables are discussed in relation to their influence on lamb eating quality and as a way to tailor lamb eating quality attributes familiar to consumers in the importing country.     

Eating quality of lamb meat: effects of breed, sex, degree of maturity and nutritional management

The eating quality of lamb meat of three indigenous Greek dairy breeds of sheep, reared under different nutritional management conditions, was assessed by Taste Panel Tests (TPT). Lean samples from the leg joints of 69 lamb carcasses of the Boutsko (B), Serres (S) and Karagouniko (K) breed were used. For the first TPT, 24 lambs (four males and four females of each breed) were reared in individual pens on a concentrate ration fed ad libitum. For the second TPT, 27 individual penned male lambs were fed on Lucerne hay ad libitum and on three different levels of concentrate: High (H), Medium, (M) and Low (L). For the third TPT, 18 male lambs were used; initially the groups were fed indoors for 63 days on three different levels of concentrate (H, M and L) together with ad libitum Lucerne hay, and subsequently finished on irrigated, sown pasture. For TPT 1, leg joints were obtained from lambs that had been slaughtered at 30, 45, 60 or 90% of mature weight (PMW) for each breed. For TPT 2, lambs were slaughtered at 23, 28 or 33 kg target slaughter live weights (TSLW), common for all breeds. For TPT 3, lambs were slaughtered at 48 or 55% of PMW for each breed. Panellists assessed warm, roasted lean samples of leg joints and rated Flavour, Juiciness, Tenderness and Overall Acceptability. In TPT 1, degree of maturity significantly affected Flavour, Tenderness and Overall Acceptability whereas sex affected only Flavour. In TPT 2, breed and concentrate level significantly affected the quality characteristics, but concentrate level had no significant effect in TPT 3. Effects associated with slaughter weight were significant for most characteristics in all TPT, with decreasing acceptability for older/heavier lambs. Significant interactions were found between breed and the other factors in TPT 2 and TPT 3 for most quality characteristics. Results from these studies suggest changing traditional production systems may enhance the eating quality of lamb meat.     

Mineral composition of lamb carcasses from the United States and New Zealand

The mineral composition-iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), fluoride (F), and phosphorus (P) (New Zealand lamb only)-of lean tissue from lamb retail cuts was studied. Twenty-four US lamb carcasses of different ages (5 to 11 months), geographical regions (Texas, Colorado and Montana) and USDA quality grades (Prime and Choice) and 27 New Zealand lamb carcasses from three weight groups (11 to 12·5 kg, 13 to 14·5 kg, and 16·5 to 18 kg), age rangining from 7 to 8 months, were selected for use in this study. Mineral concentrations were influenced more by retail cut and age than by quality grade or weigth group. Foreshank and shoulder cuts from both the US and New Zealand group consistently had the highest (P < 0·05) Zn content among the cuts. The K content of the muscle in US lambs increased as age increased, while the level of Ca and Zn in New Zealand lambs decreased as carcass weight increased. Except for Ca, the mineral concentrations of the lean tissue from US lambs were higher than the New Zealand lambs, although the differences were not always significant. US lambs had approximately 20%, 30% and 37% more Fe, Zn and Mg, respectively, but 27% less Ca than lean tissue from the New Zealand lambs.     

Carcass performance and meat mineral content in Balouchi lamb fed pistachio by-products

This experiment investigated the effect of pistachio by-products (PB) in the feed of weaned Balouchi lambs on their daily gain, carcass traits and on the levels of Ca, Zn, Fe and Cu of Longissimus dorsi muscle. Twenty eight male lambs were divided into four groups with 7 lambs each and fed separately for 90days. The first group (control) was fed a commercial concentrate, and the second, third and fourth (test) groups received diets in which 10, 20 and 30% PB was used in partial replacement of alfalfa hay and beet pulp. The results showed that the high level of PB had no effect on performance and carcass traits. There were no significant differences between groups in mineral content in Longissimus dorsi muscle. These results suggested that PB can be use in diet of fattening lambs up to 30% without any adverse effects on carcass performance and mineral content of lamb meat.     

Tissue residue depletion of moxidectin in lambs (Ovis aries) following subcutaneous administration

To date, a tissue depletion study of moxidectin (MOX) in lambs is not available. Thus, considering that lamb meat is of great commercial interest in the world, the aim of the present study was to determine the residue levels of MOX in lamb target-tissues (muscle, liver, kidney and fat) and subsequently calculate the MOX withdrawal period. For this purpose, the target-tissues were analysed by ultra-high-performance liquid chromatography-tandem mass spectrometry. Method validation was performed based on Commission Decision 2002/657/EC and VICH GL49. To quantify the analyte, matrix-matched analytical curves were constructed with spiked blank tissues. The limits of detection and quantitation were 1.5 and 5 ng g^?1, respectively, for all matrices. The linearity, decision limit, detection capability accuracy and inter- and intra-day precision of the method are reported. The lambs were treated with a single subcutaneous dose of 0.2 mg MOX kg^?1 body weight and were slaughtered in accordance with accepted animal care protocols. Samples of target-tissues were collected on 2, 4, 7, 14, 28 and 42 days after MOX administration. During the whole study, the highest drug residue level occurred in the fat. For the other target-tissues (muscle, liver and kidney), MOX concentrations were below the maximum residue limit (MRL). Considering the MRL value of 500 µg kg^?1 for MOX residues in sheep fat, our results in lambs allowed the estimation of a MOX withdrawal period of 31 days. This indicates that the withdrawal period established for MOX in adult sheep (28 days) does not apply for lambs.     

Effect of type of suckling and length of lactation period on carcass and meat quality in intensive lamb production systems

This study examined the effect of the type of suckling and length of lactation period on carcass characteristics and lamb meat quality in the Manchega Spanish breed. Fifty-eight lambs were divided into three groups differing in their management systems from birth to slaughter: The first group (W; n=21) was weaned at 35 days old. In the second one (HW; n=18) ewes were subjected to milking simultaneously with suckling of lambs ("half milk") from 15 to 45 days old. The third group (UW; n=19) remained with their mothers from birth to slaughter. UW lambs had higher dressing proportion (48.3%) than the other two groups, a higher fatness score (6.1) and larger amounts kidney and pelvic fat (342.63 g). Shrinkage losses and carcass conformation score did not differ among groups. Among the meat quality traits, UW lambs had higher L* parameter values (50.2). No statistical differences were found in the other parameters assessed.     

The effect of spineless cactus (Opuntia ficus-indica f. inermis) supplementation on growth, carcass, meat quality and fatty acid composition of male goat kids

Lambs from two Turkish breeds, Kivircik a meat breed and Sakiz a breed used for milk and meat production, were fed a diet containing commercial concentrate and hay in the ratios of either 75:25 or 25:75. The effects on fatty acid composition were studied. After weaning (at about 8 weeks) a total of 40 male lambs (20 Kivircik, 20 Sakiz) were divided into four groups of 10 animals and fed either commercial concentrate or grass hay-based diets. The lambs were group fed indoors for 60 days. The mean intramuscular total fatty acid content of longissimus dorsi for Sakiz was lower than that for Kivircik lamb. Increasing the dried grass percentage in the ration decreased the final live weight of the lambs but intramuscular total fatty acid content increased (2088 vs. 1791mg/kg muscle, p<0.001). All n-3 polyunsaturated fatty acids were higher in muscle from lamb fed dried grass-based diets than from lambs fed concentrate-based diets whereas all n-6 were higher in the latter. Polyunsaturated:saturated ratios were higher in the latter animals; 0.26 compared with 0.16 in the lambs fed grass hay. Concentrate groups displayed a higher n-6/n-3 ratio in the same muscle, 7.11 compared with 1.28 in the lambs fed grass. Muscle from Kivircik lambs had higher concentrations of C18:2 n-6 and its metabolite C20:4 n-6 (p<0.001) and also C18:3 n-3.     

The volatile compounds in lamb fat are affected by the time of grazing

This study was designed to assess whether different grazing managements affect the appearance of organic volatile compounds (VOC) in lamb fat. Forty-two lambs were divided into four groups: 9 lambs were restricted in stall and fed concentrate (S group); 12 lambs grazed from 9 am to 5 pm (8 h group); 10 lambs grazed from 9 am to 1 pm (4hAM group) and 11 lambs grazed from 1 pm to 5 pm (4hPM group). After 72 days on feed the animals were slaughtered and the perirenal fat subjected to SPME-GC/MS analysis of VOC; the data were analyzed by stepwise discriminant analysis. The 6-methyl-2-heptanone and furanone, 2,5-dimethyl, 4-hydroxy-3(2H) allowed discrimination between the 4hAM and the 4hPM animals. These are the first results indicating that the time of the day in which the animals are allowed to graze affects the appearance of VOC in lamb fat.     

Effect of dietary oil source on the flavour and the colour and lipid stability of lamb meat

This study investigated the influence of five sources of dietary oil (linseed oil (LO), fish oil (FO), a protected lipid supplement (PLS, 18:2 to 18:3 ratio 3:1), fish oil/marine algae (FOMA) and PLSMA) on the colour and lipid stability of lamb muscle and the flavour of grilled loin chops. LO produced the highest proportion of 18:3n−3 in muscle phospholipid, the highest ratings for lamb flavour intensity and overall liking and the lowest ratings for abnormal flavour intensity. PLS increased the proportion of 18:2n−6 which reduced lamb flavour intensity and increased abnormal lamb flavour intensity. Diets containing FO or MA increased proportions of the longer chain n−3 fatty acids and similar reduced ratings for lamb flavour as the PLS diet. FO-containing diets increased fishy flavour notes, especially when in combination with MA. ‘Putty’ and ‘fish oil’ odours were recognised as being present more frequently in cooked subcutaneous lamb fat from lambs fed FO and FOMA than other diets. Lambs fed MA, FO and the combination of the two produced meat that was oxidatively less stable and had a reduced colour and lipid oxidative shelf-life, which was at least partially due to the lower vitamin E content of the muscle.

These results have significant implications for the formulation of diets that may improve nutritional ratios in lamb meat but which adversely affect flavour and meat stability.     

Sensory quality of meat from lambs fed garlic

The objective of this study was to determine whether the inclusion of garlic in a ration would have a negative impact on the flavour of lamb. The study used meat from 31 Merino wether lambs fed diets with varying levels of garlic (0%, 1.8% and 3.6%) for 10 weeks. Cooked samples of meat from the lambs were assessed for flavour and acceptability as lamb by an untrained consumer panel. There was no difference (P>0.05) between the treatments in flavour score, but the 3.6% garlic treatment group scored significantly higher in terms of acceptability as lamb (P<0.05) and was commented on positively by the panellists more frequently than the meat from any other treatment (P<0.05). These results suggest that the inclusion of garlic into the animals' feed did not have a negative impact on the flavour of the lamb and, at the high rate (3.6%), made the meat more acceptable to the panellists.     

Performance of growing–fattening lambs fed diets containing different proportions of cotton seed meal

A lamb feedlot study was conducted to evaluate the nutritional value of cotton seed meal (CSM) as compared with that of sunflower meal as protein supplements for growing lambs. Forty-five Karagouniko male lambs immediately after weaning, having an average liveweight of approximately 14.7 kg, were assigned randomly to one of three growing lamb rations. CSM substituted for sunflower meal in a growing–finishing feedlot diet at levels of 0, 10 and 20% to provide 0, 50 and 100% of supplemental protein requirement, respectively. Diets were fed ad libitum and water was offered freely. All diets were approximately isonitrogenous and isocaloric. After being fed for 61 days and having reached a liveweight of approximately 27.6 kg, five lambs from each treatment were slaughtered and carcass data were collected. No significant differences (P > 0.05) in feed intake or the weight increase of lambs were found among groups given the 0, 10 and 20% treatments, indicating that lambs utilized CSM as effectively as sunflower meal when fed on an equal crude protein and crude fibre basis. The dressing percentage of the cold carcass, but not the warm carcass, and intestinal content weight were significantly influenced (P < 0.05) by the diet. Cooler shrink and intestinal fat, and perirenal fat and the combined weight of intestinal and perirenal fat were significantly (P < 0.05) correlated. Feeding margin was highest for the control diet, intermediate for the 10% CSM diet and lowest for the 20% CSM diet. It was concluded that CSM is accepted readily by growing sheep and can be incorporated into diets as a source of supplemental protein for growing–fattening lambs. No evidence of gossypol toxicity was noted. © 1999 Society of Chemical Industry     

A comparison of the quality of meat from lambs reared intensively indoors and conventionally on grass

A comparison was mack between lambs reared in two different ways. In the first method the lamb was unweaned prior to slaughter and in the second, after 12–36 h the lamb was removed from its ewe and fed cold milk for 20 days, then pelleted concentrate, and later, barley-protein concentrate with hay. The results showed that intensive rearing had little effect on the quality of meat, or over-all weight of the lamb, but a significant difference in flavour was recorded.