Light Lambs Research Articles

Carcass conformation and cut composition of Creole goat from Guadeloupe

Carcass data base of 164 Creole male goats was used in order to provide factual data on the carcass conformation. Standardised procedures of carcass measuring and cutting were followed. The European official grid of light lamb is implemented for meat goat in the French West Indies and included five levels. Weights of carcass, cuts and tissues, quality scores and linear measurements were analysed. Feeding system, age at slaughter and weight were taken into account for statistical analysis. There were significant differences among carcass conformation classes (CC) for many traits except for the fat score, leg length and compactness ratio (carcass width on length): 2.2, 34.5 cm and 0.30 on average, respectively. The values of chilled carcass weight and yield and the carcass linear measurements steadily increased until conformation class 4 or 5: 6.7 to 11.2 kg, 49% to 55% and 52.4 to 58.0 cm carcass length. For the weights of carcass cuts, significant differences appeared between two groups: classes 1 and 2 vs. classes 3, 4 and 5. Regardless of the carcass weight, the distribution of prime cuts remained similar. The indices calculated on a weight basis (kg/cm), either for the carcass or the leg, increased significantly (P<0.01): with 54% and 63% difference between the two extreme classes, respectively. The muscle, bone and fat proportions in the shoulder did not vary between CC with 0.72, 0.22 and 0.06, respectively. Corresponding traits in leg were 0.74, 0.23 and 0.03; the last two were different (P<0.05) from class 1 to class 5. The muscle/bone ratios calculated either in shoulder or in leg ranged from 3.1 to 3.6 (P>0.05).

Carcass tissue composition in light lambs: Influence of feeding system and prediction equations

Fourty-eight Churra Tensina single male lambs were used to evaluate the effect of different feeding systems on carcass composition and predict the carcass tissue composition from joint composition and carcass measurements. Four treatments were studied: GR, unweaned lambs continuously grazing with ewes; GR + S, the same as the previous group, but lambs had free access to concentrate; DRL-GRE, lambs remained indoors with free access to concentrate and ewes grazed for 8 h/day, thereafter remaining with lambs; and DRL, lambs and ewes were kept in confinement, they had free access to concentrate and dry unifeed respectively. In the DRL-GRE and DRL groups lambs were weaned when 45 days old. Lambs were slaughtered at 22–24 kg live weight. Commercial joints from the half left carcass were obtained, recorded and dissected to determine carcass tissue composition. The feeding system had an effect on the proportion of the carcass tissue composition. GR treatment showed higher muscle (M) ( p < 0.05) and bone (B) ( p < 0.001) percentages, and a lower total fat (F) percentage ( p < 0.001) than the rest of treatments. Hence it revealed higher M/F ( p < 0.01) and lower M/B ( p < 0.05) and subcutaneous fat/intermuscular fat ratios (SF/IF; p < 0.001). Carcass composition predictions were more accurate for grams than for percentages. In predictions from joint composition, pelvic limb was the most accurate joint for grams ( R 2 = 0.84, R 2 = 0.68, and R 2 = 0.77 for muscle, bone, and fat, respectively) as well as for percentage ( R 2 = 0.65, R 2 = 0.56, and R 2 = 0.73 for muscle, bone, and fat, respectively). Predictions from carcass measurements were greater in muscle and fat grams ( R 2 = 0.87 and R 2 = 0.86 for muscle and fat, respectively) than in percentage ( R 2 = 0.58 and R 2 = 0.73 for muscle and fat, respectively). Equations to predict carcass tissue that include carcass measurements are a simple method to assess accurately saleable muscle yield from different lamb feeding systems without involving carcass damage.

CO 2 stunning procedure on Manchego light lambs: Effect on meat quality

This study examined the effect of different gas stunning methods (concentration of CO 2/time of exposure (G1: 80%90s; G2: 90%90s; G3: 90%60s; G4: 80%60s) on the initial meat quality of Manchego breed light lambs (25 kg live weight) and at 7 days post-mortem, assessed by pH, colour coordinates, water holding capacity (WHC), cooking loss (CL), drip loss (DL) shear force (SF) and lipid oxidation. An electrically stunned control group (G5) was used. Stunning method had a significant effect on pH values ( P < 0.001) as well as on pH decline ( P < 0.01). The lowest pH was found at 24 h post-slaughter in G1 and the highest one on G5. The greatest drop in pH (pH 0–pH 24) was found in G1 and G5 while the smallest in G3. In general values of colour coordinates, WHC and DL were similar in all groups. Stunning method affected CL ( P < 0.001) at 7 days post-slaughter, with the lowest values being found in G1. Significant differences among groups were found ( P < 0.05) in SF values at both post-mortem times, with less tender meat in groups stunned with 80% CO 2, especially in G1. A significant effect ( P < 0.001) due to the type of stunning was found at 24 h on lipid oxidation, with the highest value in G5. After ageing this parameter was lowest ( P < 0.05) in G1 and G4.

Meat and fat quality of unweaned lambs as affected by slaughter weight and breed

Sixty-four male lambs of two Southern Spanish breeds, a dairy breed (Grazalema Merino) and a meat breed (Churra Lebrijana), were used to study the effects of slaughter weight and breed on meat traits and intramuscular and subcutaneous fat composition. Lambs were reared following a traditional production system without weaning and slaughtered when live weight reached 12 kg (suckling) or 20 kg (light). Meat from suckling lambs of both breeds had lower fat and myoglobin contents, and was more tender and had higher scores for sustained juiciness in the sensory analysis. Fat from light lambs had lower C12:0 and C14:0 levels than fat from suckling lambs. Grazalema Merino meat had higher fat and ash contents, and its fat had higher conjugated linoleic acid content than Churra Lebrijana meat.

Influence of feeding systems on cortisol levels, fat colour and instrumental meat quality in light lambs

Forty-eight lambs were fed as follows: GR, lambs and dams grazed perennial pasture; GR+S, the same as GR except that lambs had access to concentrate; DRL-GRE, lambs in drylot and dams in rationed grazing; DRL, lambs with dams were stall-fed. DRL-GRE and DRL lambs were weaned at 45 days of age. Lambs were slaughtered when they reached 22–24 kg of live weight. Plasma cortisol concentration was determined three times before slaughter. Subcutaneous fat and meat colour, and texture were analysed. The different levels of cortisol did not affect meat quality. Both grazing systems gave yellower subcutaneous fat and redder muscles than drylot lambs. Differences between systems relating to colour and texture of the meat disappeared with ageing time, which supports the idea that grazing systems are a good alternative in order to offer similar meat to that coming from drylot systems to which consumers are accustomed. Subcutaneous fat colour was a suitable method to discriminate between grazing and drylot systems, but not within them.

Systems stunning with CO 2 gas on Manchego light lambs: Physiologic responses and stunning effectiveness

Effect of four stunning treatments using different CO 2 concentrations and exposure times (G1: 80%90 s; G2: 90%90 s; G3: 90%60 s; G4: 80%60 s) on hormonal, haematological and biochemical parameters in Manchego breed light lambs and their stunning effectiveness (% animals correctly stunned) was studied. An electrically stunned control treatment (G5) was used. G1 showed the highest plasmatic hormonal, red cell distribution (RDW) and lactate levels. Haemoglobin, mean corpuscular volume (MCV), mean cell haemoglobin (HbCM), glucose, lactate deshydrogenase (LDH), sodium, potassium and creatine kinase (CK) were highest in G5. Stunning effectiveness was maximum (100%) in G3 and G5, only 50% in G1 and G2 and minimum (30%) in G4. A discriminant analysis showed a function for discriminating between G5 and the gas stunned groups, and another one for discriminating between gas stunned groups. Only potassium and adrenaline variables marked the difference among groups.

Effect of breed on mineral composition of meat from light lambs

The proximate composition and mineral content of light lambs muscle (derived from Istrian and Dalmatian Pramenka breeds) were studied. The M. Longissimus dorsi (MLD) samples of 30 carcasses were analysed and the effects of breed and sex were studied. Although lambs of investigated breeds were similar for slaughter age (2.5 months), Dalmatian Pramenka had significantly higher carcass weights (CW; P<0.05). Breed had a significant influence on moisture and fat contents, whilst mineral composition (with the exception of selenium) was scarcely affected by breed and sex. Fat and moisture contents were significantly correlated with cold CW. The magnesium, calcium, manganese and selenium contents were significantly correlated (r=0.50, -0.46, 0.44, 0.54; P<0.05 respectively) with CW. This study contributes to characterization of lamb carcasses from Istrian Sheep and Dalmatian Pramenka breeds and provides new data on the composition of the MLD of light lambs.

Light lamb meat quality packed under modified atmospheres: effect of stunning systems (electrically v. gas)

In the present study, the effect of type of stunning (electrical v. gas) and the gas mixtures in a modified atmosphere (MA) packing system (MA-A: 30% CO2 + 70% O2; MA-B: 30% CO2 + 69.3% N2 + 0.7% CO; MA-C: 40% CO2 + 60% N2) on light lamb meat quality, obtained by 20 males of Manchego Spanish breed, was evaluated at 7, 14 and 21 days post packing. For all ageing times, gas-stunned groups reached the highest pH (P < 0.001) and shear force (SF) values (P < 0.05), and at 21 days, water losses were highest; in contrast, meat colour coordinates were lower (P < 0.001). In general, MA-B showed the highest stability for colour coordinates whereas the lowest tenderness (high SF) was found on MA-A. In this study, the gas mixture with a low carbon monoxide level (MA-B) promoted a higher colour stability and good tenderness, in comparison to the other two blends. In contrast, the conventional packaging system (type A, high oxygen levels) had a reduced tenderness and major colour instability.

Estimation of light lamb carcass composition by in vivo real-time ultrasonography at four anatomical locations1

The objectives of this study were to study the relationship between in vivo ultrasound measurements and cold carcass measurements at 4 anatomical points of the backbone, and to establish regression equations to estimate carcass composition within the cold carcass weight range for Ternasco lambs (8 to 12.5 kg) by using ultrasonic measurements taken at a single location. Measurements of subcutaneous fat and skin thickness and of muscle depth and width were taken over the 10th to 11th and 12th to 13th thoracic vertebrae and the 1st to 2nd and 3rd to 4th lumbar vertebrae. These measurements were taken at 2 and 4 cm from the nearest end of the LM to the backbone and at 1/3 of the LM width with the probe perpendicular to and parallel to the backbone. The left sides of the carcasses were dissected into muscle, fat, and bone. Body weight (22.6 kg) and cold carcass weight (10.8 kg) were representative of Ternasco light lambs. Muscle depth measured at 2 cm, 4 cm, and 1/3 of LM width remained regular, with slight ups and downs along the spine. All the pairs of in vivo ultrasound and cold carcass measurements were significantly different (P<0.05) and had small correlations. All the ultrasound measurements of muscle depth at any location or at any distance to the backbone were less than their equivalent cold carcass measurements, with differences ranging from 0.8 to 5.9 mm. Differences between ultrasound fat thickness + interface (US_FDGI) and cold carcass fat thickness were less than differences between ultrasound fat thickness and cold carcass fat thickness, ranging from -0.9 to -1.0 mm for the former and from -2.1 to -0.5 mm for the latter. The small differences in absolute values between US_FDGI and cold carcass fat thickness suggest that US_FDGI is the best measure of the real fatness level of the lambs. The best prediction equations for muscle, bone, and fat were developed with in vivo ultrasound data measured at the 1st to 2nd lumbar vertebrae perpendicularly to the backbone, but they had limited predictive value. To predict the muscle content of carcass, BW and muscle depth were included, and they explained 59% of variation. Fifty-one percent of total fat was predicted by BW and fat thickness, whereas only 17% of the variation in bone was predicted by 2 fat-related variables. The BW of lambs was an important predictor to improve regression equations but ultrasound measurements were the most important variables when a narrow range of BW was used.

Growth analysis in light lambs raised under different management systems

A quadratic polynomial model with two random regression coefficients was used to describe the growth pattern of 130 single male lambs from the Churra Tensina breed which were raised under four different management systems. Treatments were: lambs in drylot with dams indoors (DR-IND), lambs in drylot with rationed grazing ewes (DR), lambs supplemented in creep feeders continuously with dams on pasture (GR + S) and lambs with dams continuously on pasture (GR). Lambs from DR-IND and DR were weaned at 49.4 ± 5.0 days old. All lambs were weighed at birth and thereafter at weekly intervals until slaughter at the target live-weight of 22–24 kg (23.3 ± 1.5 kg). The model fitted accurately weights ( R 2 = 0.96). The effect of treatment on the linear coefficient was not significant (average 267 g/day; P > 0.05). However, the quadratic coefficient varied across management systems (0.027 ± 0.12, 0.52 ± 0.17 and 0.22 ± 0.12 g/day 2 in DR-IND, DR and GR + S, respectively, vs. −0.26 ± 0.12 g/day 2 in GR; P < 0.001). Although standard errors increased at higher ages, the residual variance was 43% reduced when using two random regression coefficients. Around 60% of the variation in the data set was accounted for by allowing the intercept and the slope to vary across individuals. It was concluded that the model was suitable to describe a nearly linear growth pattern in light lambs and accounted for mean live-weight adjustment within lots resulting from removal of lambs that achieved the slaughter live-weight earlier.

Evaluation of sheep genetic resources in North America: Lamb productivity of purebred, crossbred and synthetic populations

Lamb weights and daily gains from divergent genetic types of established purebreds, e.g., Dorset (D), Lincoln (L), Rambouillet (Ra), Suffolk (Su) and Targhee (T), and fecund-type breeds, e.g., Finnsheep (F) and Romanov (Ro), their reciprocal crosses and Suffolk sired specific cross Su(F × Ro) were evaluated. Also evaluated were lambs of the Outaouais (O) and Rideau (R) Arcott breeds and their reciprocal crosses, in addition to Synthetic I (½ F, ½ L), Synthetic II (½ D, ½ Ra) and Synthetic III (¼ F, ¼ L, ¼ D, ¼ Ra) populations. The established purebreds produced heavier lambs at birth and weaning, Arcott breed crosses gained weight more rapidly resulting in heavier lambs at 140 d, and fecund-type breeds produced lighter lambs (P &lt; 0.05). In general, daily gains and lamb weights of all genetic types were similar, except that fecund-type breeds produced significantly lighter lambs. Lamb weights of T were most at birth, and Su at weaning and 140 d, while F lambs weighed the least (P &lt; 0.05). Within established purebreds, Su weighed the most and D weighed the least, while L, Ra and T lambs were intermediate. Daily gains including weaning and 140-d weights of F and R cross lambs benefited from 7–9% heterosis, while the Arcott breed cross lambs not only benefited from 5–8% heterosis, but were comparable with Su lambs. At the same time, lamb performance of Su(F × Ro) was similar to the average of their parental breeds. Lambs of synthetic populations relative to the average of their respective parental breeds weighed 8–24% more at 140 d, suggesting heterosis retention. Key words: Growth, North American breeds, Finnsheep, Romanov, Arcotts, synthetic populations

Effect of feeding system on growth and carcass characteristics of Churra Tensina light lambs

Forty-eight single male lambs were used to evaluate the effect of feeding systems on carcass characteristics and fat depots of Churra Tensina light lambs. Four treatments were studied: GR, lambs and ewes were continuously grazing, no concentrate was available to them and lambs were unweaned; GR+S, as the previous one, but additionally lambs had free access to concentrate; DRL−GRE, lambs remained indoors with free access to concentrate and ewes grazed during 8 h a day, thereafter remaining with lambs; DRL, lambs and ewes were kept always in confinement, ewes had free access to dry unifeed and lambs to concentrate. In DRL−GRE and DRL lambs were weaned at 45 days old. When lambs reached 22–24 kg of live-weight they were slaughtered. Feeding system had effect on growth rates ( p < 0.05), age ( p < 0.001) and live-weight at slaughter ( p < 0.01), carcass weight ( p < 0.001), dressing percentage ( p < 0.001), fatness thickness ( p < 0.01) as well as on the subjective classification parameters, as carcass conformation score ( p < 0.001), fatness degree ( p < 0.01) and KKCF score ( p < 0.01), having the GR lambs lower values than the rest of treatments. Nevertheless, carcasses from grazing animals were classified within the normal ranges for Ternasco commercial category similar to drylot systems. Treatment had effect on pelvic ( p < 0.01) and carcass compactness ( p < 0.001) being GR carcasses less well conformed. Feeding system affected the total body fat depots ( p < 0.01), presenting GR the lowest amount. In all treatments, carcass fat depot was greater than internal fat depots (abdominal, pelvic and renal) ( p < 0.05). Grazing treatments (GR and GR+S) presented higher proportion of anterior-rib and lower proportion of breast in relation to indoor lambs (DRL−GRE and DRL). The feeding system did not affect the proportion of first category of commercial meat. It was concluded that light lamb carcass characteristics were slightly affected by the feeding systems, being carcasses from grazing lambs classified within the normal ranges for Ternasco commercial category, similarly to drylot systems. The small differences among the products of different feeding systems had no commercial constraint in the light lamb meat market.

Haematological, hormonal and biochemical blood parameters in lamb: Effect of age and blood sampling time

This study examined the effect of blood sampling time (farm, transport, lairage) on welfare physiological indicators in two groups of different age/weight Manchega breed lambs (suckling vs light). Blood sampling time had a different effect on both types of lamb: In light lambs, there was an increase ( P < 0.001) in red blood cells (RBC), haemoglobin, hematocrit and urea after lairage; but adrenaline, glucose and creatinine increased after transport. In suckling lambs, there were higher values of cortisol and potassium on the farm, both glucose and sodium increased after transport while adrenaline did after lairage. In general, significant differences ( P < 0.001) were found between both types of lamb in the parameters analysed. Light lambs showed higher values of RBC, haemoglobin, hematocrit, adrenaline, noradrenalin, LDH, CK, sodium and lactate than younger animals in all blood sampling times. Only after lairage were urea and leucocytes lower ( P < 0.05) in suckling than in light lambs, while cortisol was higher on the farm and lower after lairage in younger animals.

Effects of feeding system on carcass and non-carcass composition of Churra Tensina light lambs

Thirty-eight single male lambs (3.6 ± 0.08 kg live weight at birth) were used to study the influence of feeding system on carcass and non-carcass composition of Churra Tensina light lambs. Treatments: indoor (IND), lambs housed indoors consuming concentrate ad libitum until weaning at 53 days of age, and ewes grazing 8 h a day without their offspring and receiving a supplement of barley meal after grazing; grazing (GR), ewes and lambs grazed continuously without concentrate and lambs were unweaned. When lambs reached 22–24 kg live weight they were slaughtered. Carcass and non-carcass composition was recorded. GR lambs displayed higher carcass shrink ( P < 0.05) and lower dressing percentage ( P < 0.01) than concentrate-fed lambs. IND lambs had more body fat mainly due to the heavier kidney ( P < 0.001) and subcutaneous ( P < 0.001) fat depots. Total non-carcass weight was not affected by treatment ( P > 0.05), but red organ (heart, lung and trachea, thymus, liver, spleen, kidney, diaphragm, pancreas, gall bladder, bladder, and testicles and penis), digestive tract (stomach, small intestine and large intestine) and head, skin, and feet (HSF) weights differed between treatments ( P < 0.05). IND lambs had heavier red organs and HSF ( P < 0.05) although this difference disappeared when expressed as a percentage of empty body weight. Small intestine weight in grazing lambs was heavier ( P < 0.001) and, consequently, the total digestive tract differed similarly ( P < 0.01). Treatment influenced the weights ( P < 0.05) of all joints except leg ( P > 0.05), showing heavier joints for IND carcasses. The feeding system had a greater effect on subcutaneous fat ( P < 0.001) than on intermuscular fat ( P < 0.05) in most of the standardized joints. IND carcasses produced a greater proportion of muscle/bone in all joints, except neck, whereas GR produced a greater proportion of muscle/total fat due to the lower amount of fat recorded in this treatment. The percentage of fatty acids was not affected by treatment ( P > 0.05) although the percentage of C18:3 was greater and the ratio of C18:2/C18:3 was lower in grazing-fed lambs. The absence of any effect of treatment on the fatty acid percentages may be influenced by the short raising period and by the similar amount of intramuscular fat in both treatments. It is concluded that light lambs reared under grazing conditions can produce carcasses of acceptable quality, due to the lower percentage of subcutaneous fat, but with a similar intramuscular fat content.

Effects of previous diet and duration of soybean oil supplementation on light lambs carcass composition, meat quality and fatty acid composition

Forty Merino Branco ram lambs were used to study the effects of initial diet and duration of supplementation with a conjugated linoleic acid (CLA) promoting diet, on carcass composition, meat quality and fatty acid composition of intramuscular fat. The experimental period was 6 weeks. The experimental design involved 2 initial diets (commercial concentrate (C); dehydrated lucerne (L)), and 2 finishing periods (2 and 4 weeks) on dehydrated lucerne plus 10% soybean oil (O). Data were analysed as a 2 × 2 factorial arrangement with initial diet and time on finishing (CLA promoting) diet as the main factors. The lambs were randomly assigned to four groups: CCO; COO; LLO; LOO according to the lamb’s diet fed in each period. Lambs initially fed with concentrate showed higher hot carcass weights (11.2 vs 9.6 kg) than lambs fed initially with lucerne. The increase of the duration of finishing period reduced the carcass muscle percentage (57.4% vs 55.5%) and increased the subcutaneous fat percentage (5.67% vs 7.03%). Meat colour was affected by initial diet. Lambs initially fed with concentrate showed a lower proportion of CLA (18:2 cis-9, trans-11 isomer) (0.98% vs 1.38% of total fatty acids) and most of n−3 polyunsaturated fatty acids than lambs initially fed with lucerne. Initial diet did not compromise the response to the CLA-promoting diet and the proportion of 18:2 cis-9, trans-11 in intramuscular fat increased with the duration of time on the CLA-promoting diet (1.02% vs 1.34% of total fatty acids).

Effect of live weight and sex on physico-chemical and sensorial characteristics of Merino lamb meat

Forty-eight lamb carcasses were divided into four groups ( n = 12) according to slaughter weight (24 and 29 kg) and sex (male and female). Colour, pH, moisture, and intramuscular fat were not affected ( p > 0.05) by slaughter weight or sex. With respect to fatty acid composition, slaughter weight had significant effects on C12:0 ( p < 0.01), C14:0, C16:0, and C18:1 n-9 ( p < 0.05) in Longissimus lumborum (LL) muscle. The percentage of C12:0 and C14:0 decreased as slaughter weight increased, while C16:0 increased. In Semimembranosus (SM) m., only C18:3 n-3 and C20:2 n-6 were affected ( p < 0.001) by slaughter weight. Total PUFA in LL m. was greater ( p < 0.01) in females than in males. Although in general, sensorial quality was not significantly affected by slaughter weight or sex, meat from lighter lambs (24 kg) had greater general acceptability than meat from heavier lambs (29 kg).

The welfare of the neonatal lamb

The neonatal period is the most vulnerable time in the life of a lamb, with almost half of all pre-weaning mortalities occurring on the day of birth. The welfare challenges faced by the neonate include hunger, hypothermia, pain and injury resulting from the birth process and management interactions, as well as sickness from infectious diseases and distress from maternal separation. A difficult lambing can result in death of a lamb, which may occur without significant suffering on the part of the lamb if pulmonary respiration has not been established, but it can also lead to delivery of an injured lamb. Such animals, in addition to suffering pain as a result of the trauma, are generally less vigorous, slower to suck and may establish a weak relationship with their mother. The main risk factor for both increased lamb mortality and increased difficulty in coping with welfare challenges is low lamb birth weight. Lighter lambs are less vigorous at birth, take longer to suck successfully, thereby increasing their risk of infection, and have a reduced ability to maintain body temperature compared to heavier lambs. These lambs may also have increased stress reactivity throughout life. The appropriate management of the ewe during pregnancy and provision of an optimal birth environment can help minimise the welfare challenges experienced by the lamb, which stem from poor neonatal adaptation to postnatal life and a poor maternal relationship. Breeding for ease of delivery, appropriate behavioural characteristics and cold resistance in the lamb may also be long-term solutions to reduce lamb welfare issues. However, management actions can also be a source of poor welfare in the neonatal lamb, particularly carrying out painful procedures without the use of analgesics, and disruption of the ewe–lamb bond by permanent or temporary separation. Whilst some of these challenges may be unavoidable, consideration of the costs to the lamb of the procedure, and that lambs are better able to cope with welfare challenges when these occur with the presence of their mothers, may help to relieve some aspects of poor welfare in the young lamb.

Effect of birthweight on survival in triplet-born lambs

Lambing percentage is the main contributor to higher profit on New Zealand sheep farms and has increased from 98% in 1960 to 124% in 2006. As ewe litter size increases so does the proportion of triplet-born lambs and consequently preweaning mortality rate. The purpose of this study was to investigate the effect of birthweight (BWT) on survival in triplet-born lambs within and among litters. Data from a total of 594 triplet crossbreed lambs born to mixed-age ewes was analysed. For the statistical analysis, the lambs were allocated according to their BWT, and within the litter were then allocated to three BWT groups (light, medium and heavy). The following parameters were calculated: total litter BWT (TBWT), percentage of TBWT for each lamb (PBWT = BWT/TBWT), coefficient of variation for BWT within litter and lamb average daily gain from birth to weaning. The mortality rate for the light, medium and heavy lambs was 56, 40 and 28%, respectively, and consequently the lightest lamb in a litter was 3.2 times more likely to die than the heaviest lamb. In the light lamb group, as BWT increased mortality decreased (P = 0.006), for medium lambs BWT did not influence mortality (P = 0.88) and in the heavy group there was a trend of increased BWT associated with increased mortality (P = 0.10). The negative relationship between lamb mortality and PBWT was identical in the three BWT groups (P &lt; 0.0001). The effect of BWT on lamb mortality became non-significant when PBWT was fitted in the same model. This means that, in triplet-born lambs, mortality is not influenced by the BWT of the lamb itself, but by the BWT of its littermates. It can be calculated that a 4-kg lamb has a 24% chance of surviving in a litter of 16 kg, a 60% chance in a litter of 12 kg and an 87% chance of surviving in a litter of 8 kg. It is concluded that reducing the variation in BWT within a litter, or specifically managing the lightest lamb at birth, will increase the competitive ability for survival of each lamb and, therefore, decrease overall mortality and further improve farm profitability.

Meat and fat colour as a tool to trace grass-feeding systems in light lamb production

Ninety-five lambs were fed as follows: lambs and dams grazing alfalfa (Gr); As Gr but lambs had access to concentrate (Gr+S); ewes grazed and lambs received milk and concentrate until weaning and thereafter concentrate and straw (Rat-Gr); ewes and lambs were stall-fed (Ind). Lambs were slaughtered at 22–24 kg of live-weight and fat and M. rectus abdominis colour measured. Visual appraisal scores of Gr and Ind were significantly different. The absolute value of the integral of the translated spectrum (SUM) was greater in Gr and GR+S. A discriminate analysis was able to discriminate between grass-fed and indoor-fed lambs. A logistic regression including SUM and b∗ classify correctly 99.1% of carcasses. A equation is proposed to calculate the probability of one carcass to do not belongs to Gr or Gr+S group (PNA): PNA=11+e-(-1.953+1.320·b∗-0.115·Sum).

Management of maternal-offspring behavior to improve lamb survival in easy care sheep systems1,2

This paper examines the environmental and management factors affecting lamb survival on high-performing sheep farms in New Zealand. Improved lambing percentage is the biggest contributor to higher profits on New Zealand sheep farms. Many sheep breeders have selected and bred ewes for increased fecundity over the last 4 decades. The increased proportion of ewes having triplets is of concern to farmers and to industry because neonatal lamb mortality is highest in triplets. The majority of lamb deaths occur in the first 3 d after birth and range from 5 to 30% for individual sheep flocks. The ability of a lamb to survive to weaning is determined by genetics, behavior, physiology, and the environment, including on-farm management practices. We investigated the effects of dam body condition in pregnancy, weather during lambing, lamb birth weight, and maternal behavior on single, twin, and triplet lamb viability at birth, lamb death risks from dystocia, and starvation exposure and survival through to weaning for 20 industry flocks from 2003 to 2004 (15,821 lambs). Ewes with higher body condition scores in mid pregnancy had heavier lambs at birth (P < 0.01). Lambs weighing 5.5 to 6 kg at birth (P < 0.01) were more likely to be viable at birth and survive to weaning than heavier or lighter lambs. Weather conditions during late pregnancy (P < 0.05) proved more important than conditions during lambing (P < 0.05) in determining lamb viability and survival through to weaning. Older ewes and ewes with triplets require considerably more attention for farmers to realize their production potential. This information can help formulate appropriate management programs to improve lamb survival rates under easy care farming systems.