Testicular development, ultrasonographic and histological appearance of the testis in ram lambs immunized against recombinant LHRH fusion proteins

Sixteen native ram lambs weaned at 10 wk of age were divided into two groups. Eight animals were immunized against LHRH with a mixture of two fusion proteins: ovalbumin-LHRH-7 and thioredoxin-LHRH-7. The immunized lambs received a primary immunization plus two booster immunizations at 4 and 12 wks. Animals in the control group (n=8) were not treated. Scrotal measurements and blood samples were taken at 2-week intervals. Beginning at 25 wk of age, semen was collected and sexual behaviour was evaluated on a weekly basis. At 35 and 37 wk of age testes and accessory glands of all animals were subjected to ultrasound scanning. At 37 wk of age animals were slaughtered and testes were evaluated histologically. Serum LHRH antibodies (P<0.01) were detected in animals of the immunized group which had reduced serum testosterone concentrations (P<0.01). Testicular development was suppressed in the immunized animals (P<0.01). Immunized animals exhibited mounting activity 5 wks later than control animals. No mature spermatozoa containing ejaculates were collected from immunized animals. Control animals had moderately echogenic ultrasonographic appearance at 37 wk age, whereas immunized animals had hypoechogenic images. Mean seminiferous tubule diameter in immunized lambs was significantly smaller than that in control lambs. Basal membrane was thickened and hyalinized; there was an increase in peritubular connective tissue. No proliferating spermatogonia or mature spermatozoa were present in the tubules in these animals. There were no differences in the ultrasonographic appearance of prostate and vesicular gland between control and immunized animals. The LHRH recombinant fusion proteins were effective in immunological castration in ram lambs when started at 10 wk of age as noted by differences in serum testosterone, testicular histology and ultrasonographic appearance of testis and weight of accessory sex glands. Determining the effects of immunization on ultrasonographic appearance of the testis related to time after immunization requires further investigations.     

The Liver Cells in Acute Starvation and Refeeding

A series of 52 young male white laboratory mice were starved for a maximum of five days, and 45 normally fed animals were used as controls. A group of experimental animals and a corresponding control group were sacrificed after two, three, and four days' starvation and after six, 12 and 17 days' refeeding. Even after two days the animals had lost weight, and the liver cells had diminished highly significantly. A return to the initial values was noted after 12 days' refeeding. In the experimental animals a strong negative correlation was noted between the cell count per field and body weight (r =–0.712, b =–7.520), while no such correlation was observed for the controls. The volume of the liver cells was reduced by 61.7 %, the volume of their nuclei by 16.2 % after four days' starvation. After two to three days' starvation the liver cells often showed a slight accumulation of fat. Mitoses were frequent in the liver cells during the stage of regeneration, when the cells had attained the same size as in the controls.     

Partial replacement of barley grain and soybean meal by fleabane (Conyza bonariensis) in diets of growing Awassi lambs

Effects of partial substitution of barley grain and soybean meal with fleabane (FB) Conyza bonariensis on growth performances and body compositions of 24 male local Awassi lambs were studied. All lambs were male with an average BW of 20.3 kg (s.d. = 2.0 kg) at the beginning of the experiment. Animals were randomly divided into four groups of six lambs each. Lambs in each group received individually their cereal–soybean-based total mixed rations with levels of FB: 0, 50, 100 and 150 g/kg dry matter (DM) diet, which replaced similar values of barley and soybean meal. All rations were isonitrogenous and isocaloric. The fattening experiment lasted 9 weeks, after which all lambs were slaughtered. The composition of nutrients in the C. bonariensis were 89.6%, 15.0%, 28.0%, 30.0% and 10% for organic matter, CP, NDF, ADF and lignin, respectively. At the end of the experiment, lambs fed 100 and 150 g FB/kg DM diets gained more weight (P < 0.05) than those fed the control and 50 g FB/kg DM diets. The DM intake was lower in lambs fed the highest level of FB compared with intakes of lambs in other treatments. Diet content of FB had significant effect (P < 0.05) on weights of empty body, carcass, gut and external (hide, head and feet) among all animals. However, FB had no effects on lambs’ thoracic organs (lungs and heart) and liver. Muscle, bone, omental and mesenteric fat, subcutaneous, intermuscular, pelvic and kidney fat weights (g/kg empty BW) were not affected by FB feeding. Carcass fat was decreased (P < 0.05) by the increase of FB. Total body fat was the same in all animals of the experiment.     

Absorption of experimentally administered materials by the hepatopancreas cells of the crayfish, Procambarus clarki

After long term starvation, the crayfish, Procambarus clarki was administered protein silver, iron lactate and olive oil, and its hepatopancreas was subsequently examined by electron microscopy. The reserve cells showed changes suggesting the absorption of these materials from the acinar lumen had taken place. In contrast, the hindgut of crayfish seemed to have no absorptive ability. In crustaceans the hepatopancreas is the largest gland in the body. The chief functions of this gland are the secretion of digestive juice into the stomach and absorption of digested food. It is also where materials which are necessary for hardening of animals that have undergone ecdysis are stored. Although these roles are commonly accepted, the absorptive ability of the gland has been rarely studied. Yonge (1924) and van Weel (1955) attempted to obtain evidence for the absorptive function of hepatopancreas cells of Nephrops norvegicus and Atya spinides using iron lactate and iron saccharate, and obtained some positive results. They used the histochemical Prussian blue test to demonstrate absorbed iron. Vonk (1960) referred to the results of a few authors who had tried to show fat deposits in reserve cells of the hepatopancreas after the administration of olive oil to the animals. But because starvation did not affect the quantity of stored fat in the hepatopancreas cells, the attempt failed to reveal the absorption of fat by the hepatopancreas. In the present paper, the authors describe the results of studies on the absorption of experimentally administered materials by hepatopancreas cells of the crayfish, Procambarus clarki, using electron microscopy.     

The effects of dietary chromium supplementation on some blood parameters in sheep

The effects of dietary inorganic chromium on some biochemical parameters were determined in lambs fed either a control diet or a 200-ppb or 400-ppb chromium-supplemented diet. The live weight of the animals were measured and jugular blood samples were collected prior to supplementation (d 0) and on d 20, 40, and 55. On d 55, three animals from each group were slaughtered to measure subcutaneous fat. Sera were analyzed for glucose, triglyceride, total cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, total protein, albumin, ALT, AST, and GGT levels. Chromium supplementation had no significant effect on live weight, but subcutaneous fat was reduced significantly in both chromium groups. There was a slight decrease in glucose concentrations in the 200-ppb chromium group, although only the differences on d 55 were significant. Triglyceride levels in both chromium groups were lower than the control group with marked differences in the 400-ppb chromium group. HDL cholesterol levels increased in both treatment groups compare to control, although the differences in the 400-ppb chromium group on d 40 were significant. Serum Cr concentrations slightly but not significantly increased in both chromium groups. No significant differences were found in total and LDL cholesterol, total protein, albumin, ALT, AST, and GGT levels. In conclusion, chromium supplementation may affect carbohydrate and lipid metabolisms and lipid deposition in lambs.     

Effects of dietary sewage solids on second-generation ewes fed an experimental diet from weaning through two reproductive cycles

Eighteen fine-wool ewe lambs produced by mature, conventionally fed dams and 21 similar offspring from sewage-fed ewes were randomly allotted at weaning to one of two groups. Half of the lambs from each maternal diet group received a conventional (18% protein) diet during the growing phase while the remainder was fed the conventional diet plus 7% undigested, irradiated sewage solids (18% protein). At the end of the 147-day growing period and just before a fall breeding season, conventionally fed ewe lambs were switched to a control diet (12% protein) suitable for mature ewes and sewage-fed ewe lambs began receiving the control diet plus 7% sewage solids. Animals received these diets for two years. Maternal sewage consumption did not influence performance of F₁ ewe lambs. By the beginning of the first breeding season, controls were heavier (P<0.01) than were animals receiving sewage solids (51.7 and 44.5 kg, respectively). Similarly, only 75% of sewage-fed ewe lambs exhibited estrus during their first breeding season compared with 94.7% of controls (P<0.10). Conception rate (40.0 and 84.2%, respectively) and lambs born per ewe exposed (0.4 and 0.89, respectively) were also lower (P<0.05) in animals receiving sewage solids than in controls. During the second reproductive cycle, conception rate as well as lambs born per ewe exposed was comparable (P>0.10) between the two groups. Offspring from the sewage-fed ewe lambs, however, weighed less (P<0.05) at weaning than did lambs produced by control animals. Results indicate that a diet containing 7% sewage solids may not be suitable for preparing ewe lambs to go into the breeding flock; once mature size is attained, however, reproductive performance is not hampered by sewage feeding.     

Methodological developments in the use of visible reflectance spectroscopy for discriminating pasture-fed from concentrate-fed lamb carcasses

The ability to authenticate the feed given to animals from the animal products has become a major challenge for scientists, monitoring bodies and commercial entities alike. This study compared two methods based on the use of the visible reflectance spectrum of the fat to discriminate pasture-fed (P) from stall concentrate-fed (S) lamb carcasses. A total of 307 (143 P and 164 S) Limousine lambs were used over 2 years. Pasture-fed lambs grazed a permanent pasture that was maintained at a leafy, green vegetative stage, and offered ad libitum; they received no supplementation at pasture. Body weight of P lambs when turning out to pasture and at slaughter averaged 9.2 (standard deviation (s.d.) 2.21) kg and 33.2 (s.d. 2.89) kg, respectively. S lambs were fed indoors on an ad libitum diet of commercial concentrate and hay until slaughter at a mean body weight of 33.7 (s.d. 3.62) kg. The reflectance spectrum of perirenal and subcutaneous caudal fat was measured at slaughter and at 24 h post mortem. Plasma carotenoid concentration was measured at slaughter. In method 1, the fat reflectance spectrum data were used at wavelengths between 450 and 510 nm to calculate an index quantifying light absorption by carotenoid pigments. In method 2, a multivariate analysis was performed over the full set of fat reflectance data at wavelengths between 400 and 700 nm. Method 2 yielded a higher proportion of correctly classified lambs compared with method 1 (P < 0.05 to 0.001), except for measurements made at 24 h post mortem on perirenal fat for S lambs. The proportion of lambs correctly classified using method 2 was 87.4% and 92.9% for measurements made on perirenal and caudal fat at slaughter, and 93.9% and 91.0% for measurements made on perirenal and caudal fat 24 h post mortem. Plasma carotenoid concentrations were higher in P lambs than in S lambs (P < 0.001), which led to correct classification of 90.7% of the lambs.     

Influence of sex, slaughter weight and carcass weight on “non-carcass” and carcass quality in segureña lambs

The effects of sex, slaughter weight and carcass weight on carcass characteristics and meat quality traits were evaluated using 100 Segureña lambs. The management of all lambs was similar prior to slaughter at 19–25 kg. Slaughtered animals with a hot carcass weight below 20 kg were assigned to class B, and those greater than 22 kg to class C. Carcass weight had a significant influence on “non-carcass” components, dressing percentage, subjective carcass conformation, fat deposits, carcass fatness, bone and most carcass measurements. Sex had a significant effect on age at slaughter, “non-carcass” components, rib measurements, dressing percentage, fat deposits, and neck and shoulder percentage. As the weight increased, the carcass measurements also increased. Concurrently, while improving the conformation indices of the carcass, leg and dressing percentages, neither the commercial cuts of the animal nor tissue composition was significantly affected. Sex primarily affected the quantity of all types of fat deposits.     

How does barley supplementation in lambs grazing alfalfa affect meat sensory quality and authentication?

Excessive flavour in lamb meat is undesirable for consumers and can prompt purchase resistance. Volatile indoles responsible for off-flavours accumulate more in the fat of lambs on pasture than on grain and are enhanced when lambs graze alfalfa. Here, we investigated whether barley supplementation of lambs grazing alfalfa influences meat sensory quality. Using three groups of 12 male Romane lambs, we compared three feeding regimes: alfalfa grazing (AG), alfalfa grazing + daily supplementation with barley (29 g/kg live weight^0.75, AGS) and stall feeding with concentrate and hay (SF). As some of the compounds involved in meat sensory traits may act as dietary biomarkers, we also investigated potential implications for meat authentication. Although barley represented 38% of the diet in AGS lambs, it did not offer any advantage for animal average daily gain or parasitism level. Animal performance, carcass weight and fatness did not differ between feeding regimes. Dorsal fat firmness tended to be greater in AG than AGS and greater in AGS than SF. Skatole and indole concentrations in perirenal and dorsal fat were lower in SF lambs than in AG and AGS lambs (P<0.01 to P<0.0001), but did not differ between AG and AGS lambs. Yellowness, chroma and hue angle of perirenal fat were lower in SF lambs than in AG and AGS lambs (P<0.001), but did not differ between AG and AGS lambs. Absolute value of the mean integral for both perirenal fat and subcutaneous caudal fat (AVMI_PF and AVMI_SC), quantifying the intensity of light absorption by carotenoids in perirenal and subcutaneous caudal fat, respectively, were lower in SF lambs than in AG and AGS lambs (P<0.0001 for both comparisons), but did not differ between AG and AGS lambs. Meat colour was unaffected by the treatment. We confirm that lambs grazing alfalfa accumulate high levels of volatile indoles in their fat, but we show that barley supplementation to lambs grazing alfalfa is not effective in reducing fat volatile indoles concentration and excessive odour/flavour in the meat. We also confirm that both perirenal fat skatole concentration and AVMI_PF are of interest for discriminating lambs that grazed alfalfa from lambs that were stall-fed, and we show that they are not effective for discriminating supplemented from non-supplemented grazing lambs.     

Meat odour and flavour and indoles concentration in ruminal fluid and adipose tissue of lambs fed green herbage or concentrates with or without tannins

A 2 × 2 factorial experiment was carried out to evaluate the effect of herbage or concentrate feeding system and tannin addition to diet on skatole and indole in ruminal fluid and adipose tissue and meat sensory properties. Twenty-eight male lambs aged 45 days were randomly assigned to one of two feeding systems (vetch green herbage or concentrates, n = 14) and within feeding system to one supplement (quebracho tannins added to the diet or none). Animals were kept in singular pens and slaughtered at the age of 105 days. Indole (P < 0.05) and skatole (P < 0.01) concentrations in ruminal fluid were higher in lambs fed herbage compared to those given concentrates. Skatole in ruminal fluid tended to be present at lower concentrations in animals that received the tannin supplementation (P = 0.07). Indole was also higher in the caudal fat of animals fed green vetch compared to those fed concentrate (P = 0.04). Skatole concentration was lower in the fat of lambs fed concentrates compared to those given herbage (P = 0.05) and was lower in the fat of animals supplemented with tannins compared to the animals not supplemented (P = 0.01). Sheep meat odour was lower in meat from animals supplemented with tannins compared to those not supplemented (P < 0.01). It is concluded that tannins are more effective in reducing skatole formation in ruminants when they are associated with concentrate diets than green herbages.     

Breed, litter and parity effects on placental weight and placentome number, and consequences for the neonatal behaviour of the lamb

Lamb survival is impaired in low birth weight lambs, and those that are slow to stand and suck. Many of the factors that influence lamb vigour, such as parity, litter size, and breed, may exert their effects, at least partially, before birth by influencing placenta development. Our hypothesis was that retarded lamb behavioural development was due to differences in placentation in these animals. Data were collected from Blackface and Suffolk lambs in the first 2 h after birth and placentas were collected when delivered. Suffolk lambs, which were behaviourally slower and had lower rectal temperatures than Blackface lambs, were associated with larger but less efficient placentas (placental efficiency defined as foetal weight supported per g placenta) with fewer foetal cotyledons than Blackface placentas. Triplet lambs were significantly slower than twin or single lambs to suck and had lower rectal temperatures. Although placenta efficiency increased with litter size, placenta and cotyledon weight, and cotyledon number increased with twinning but not thereafter. It seemed likely that triplet lambs suffered some placental insufficiency in comparison to other litter sizes. Lambs born to first parity mothers were slower to stand and reach the udder than lambs of more experienced ewes, and first parity ewes also had smaller and less efficient placentas although cotyledon number was not affected. Male lambs tended to be slower than female lambs for most behaviours, although rectal temperatures were not affected. The sire of the lamb also influenced lamb behaviour and rectal temperature. Both lamb sex and lamb sire influenced the average weight of placental cotyledons, thus some of the sire effect on the behaviour and birth weight of his progeny might be mediated through placental development. Lamb neonatal vigour was correlated with placental efficiency suggesting that lamb behaviour immediately after birth is related to placental development and function.     

The effects of starvation and subsequent feeding on juvenile hormone synthesis and oöcyte growth in Schistocerca americana gregaria

The effect of starvation on the synthesis of C₁₆ juvenile hormone (JH) and the growth of terminal oöcytes was assessed in Schistocerca americana gregaria at two times during adult life: before activation of the corpora allata and during the first gonotrophic cycle. In both groups, starvation resulted in a decline in JH synthesis within 2–3 days and rates of synthesis remained low throughout the experimental period. The growth rate of oöcytes which were not vitellogenic at the time of starvation was depressed whereas the percentage of resorption of vitellogenic oöcytes increased dramatically with starvation. Although the percentage of resorption increased in animals with vitellogenic oöcytes, some mature oöcytes were produced, particularly in animals in which the oöcytes were greater than 5 mm in length at the time of starvation. This suggests that oöcyte maturation can be divided into two distinct phases—an early phase of vitellogenesis associated with high rates of JH synthesis and a late phase, in oöcytes greater than 5 mm, associated with much lower rates of JH synthesis.Stimulation of JH synthesis by farnesenic acid in 5-day starved animals resulted in high rates of JH synthesis, indicating that starvation did not appreciably alter the enzymic activities of the final two stages in JH synthesis. Thus rate limitation did not occur at these stages.Feeding of 5-day starved animals resulted in a transient increase in the rate of JH synthesis. However, rates of JH synthesis and oöcyte growth remained subnormal throughout the observation period, suggesting that the effects of starvation cannot be entirely reversed by feeding. Thus starvation may decrease the reproductive potential of the females.     

Carbohydrate metabolism in starved fifth instar larvae of Manduca sexta

The influence of starvation on carbohydrate metabolism in fifth instar larvae of Manduca sexta was studied. The percentage of active fat body glycogen phosphorylase increased from 10% to approximately 50% within 3 h of starvation; afterward the enzyme was slowly inactivated. The increase of phosphorylase activity might have been caused by a peptide(s) from the CC. The amount of fat body glycogen in starved animals decreased over 24 h by approximately 20 mg. The released glucose molecules seem to be converted mainly to trehalose because the hemolymph trehalose concentration in starved animals was always slightly higher than in the fed controls, and the glucose concentration decreased even when phosphorylase was activated. The chitosan content in starved larvae increased during the first 9 h of treatment to the same extent as in fed controls. It is suggested that fat body glycogen phosphorylase was activated during starvation to provide substrates for chitin synthesis and energy metabolism.     

Comparative studies on storage cells in tardigrades during starvation and anhydrobiosis

The impact of starvation and anhydrobiosis on the number and size of the storage cells in the tardigrade species Milnesium tardigradum, Paramacrobiotus tonollii and Macrobiotus sapiens was investigated to gain more insight on the energetic side of anhydrobiosis. Storage cells are free floating cells within the body cavity of tardigrades and are presumed to store and release energy in form of glycogen, protein and fat to maintain a constant nutrient regime for the other tissues. The body size of the animals was not correlated with the size of the storage cells, however, M. tardigradum the largest species analysed also had the largest storage cells. A reduction in the size of the storage cells is apparent in all three species after seven days of starvation. A seven-day period of anhydrobiosis leads to a decrease in cell size in M. tardigradum but not in P. tonollii and M. sapiens. Although M. sapiens was raised on green algae, and M. tardigradum and P. tonollii were fed with rotifers and nematodes this difference in nourishment was not reflected in the response of the storage cells to anhydrobiosis.     

Effect of Absence of Ciliate Protozoa From the Rumen on Microbial Activity and Growth of Lambs

A survey of the components of the rumen ciliate population in a series of adult sheep, raised in the Faculty of Agriculture, University of Alexandria, has shown that a mixture of Entodinium, Isotricha, Ophryoscolex, Diplodinium, and Polyplastron species was found in the rumen contents of Egyptian sheep; no Epidinium and a negligible number of Dasytricha ruminantium were also observed. The microbial population, reducing sugars, ammonia, volatile fatty acids (VFA) production, and growth rate of 14 lambs inoculated with whole rumen contents from a mature sheep were compared over a 6-month period with those of 13 lambs maintained under the same conditions, except that they were strictly isolated from other ruminants. Certain large oval organisms and large numbers of flagellates and Oscillospira were frequently observed in the rumen contents of the isolated lambs. The reducing sugars, ammonia, and VFA levels, measured before and at intervals after feeding, in the inoculated lambs showed a pronounced rise above the values found in the ciliate-free animals. The propionic acid-acetic acid ratio in the rumen contents of the faunated lambs was considerably higher than in the nonfaunated controls. The inoculated lambs grew faster than the isolated lambs. Differences in weight gain which ranged from 15 to 17% were statistically significant. The inoculated animals impressed the observers by their good appearance which was superior to that of the ciliate-free lambs. It was, therefore, concluded that the rumen ciliate protozoa are essential for the metabolism and growth of young lambs.     

Estrus without ovulation in puberal ewes

In three groups of puberal sheep, one of young Merino ewes and one of Merino ewe lambs at Armidale, Australia, and one of Perendale ewe lambs at Hamilton, New Zealand, 20, 33 and 6.6% respectively of the animals failed to ovulate at their first estrus. Duration of estrus and intensity of overt estrous symptoms in these animals were the same as in their ovulating contemporaries. While the anovulatory estrus was followed by estrus with ovulation in most animals, many of the Merino lambs had a second anovulatory estrus and then went into anestrum. In some animals, failure of ovulation was followed by luteinization of a large follicle. In the Perendale lambs, the inter-estrous period following an anovulatory estrus was 15.9 days compared to 16.7 days in their ovulating contemporaries. The occurrence of anovulatory estrus in these three different groups of animals suggests that it is common in the first breeding season of young ewes. Lambing percentage probably is reduced below the expected level by the presence in the flock of ewe lambs that have had an estrus but not yet reached puberty.     

饥饿对太平洋鲑生长、机体组成及血浆相关生化指标变化研究

实验研究了太平洋鲑鱼(Oncorhynchus spp.)经8-32d饥饿后对其生长、体组成与血浆生化指标变化的影响。90尾初始重约为217g的太平洋鲑鱼放养于0.25m3的水族箱中0-32d,水温为(17.0±2.9)℃。实验分5组,分别为对照组(饥饿0d)、实验1组(饥饿8d)、实验2组(饥饿16d)、实验3组(饥饿24d)、实验4组(饥饿32d)。每组3个平行,每箱6尾鱼。结果表明:饥饿期间,太平洋鲑鱼存活率均为100%,相对体重损失率与饥饿时间直线回归方程为y=0.0086x(R2=0.9177),呈显著的正相关(P0.05);肠系膜脂肪是太平洋鲑鱼最主要的能量来源,与饥饿时间呈显著的负相关(P0.05),其直线回归方程y=-0.0719x±4.11(R2=0.9732);饥饿初期太平洋鲑鱼主要消耗肝脏糖原和脂肪、部分肠系膜脂肪和少许肌肉中脂肪维持生命活动,能耗较低;饥饿后期主要以消耗肠系膜脂肪、部分肌肉脂肪和少量蛋白质维持生命活动,能耗较高;血浆中脂肪分解酶和白蛋白无显著变化(P0.05),胆固醇、甘油三酯和高低密度脂蛋白有显著波动(P0.05),表明脂肪代谢活跃,免疫功能未受明显影响。研究表明太平洋鲑鱼能够有效地利用体内储存的脂肪,对饥饿的耐受能力较强。       

Reliability of visible reflectance spectroscopy in discriminating between pasture and stall-fed lambs from thin and fat-tailed sheep breeds in dry and hot environment

Considering the additional market value of pasture meat, many authentication methods were developed to discriminate it from meat produced in conventional systems. The visible reflectance spectroscopy technique has proved its efficiency under European conditions and breeds. The present study tested the reliability of this method to discriminate between pasture-fed (P) and stall-fed (S) lambs under North African conditions and investigated the effect of feeding system (FS) (P v. S) and breed (Barbarine; Queue Fine de l’Ouest; and Noire de Thibar) on weight and colour of perirenal, subcutaneous and caudal fat. A total of 18 P and 18 S lambs were used with 6 P and 6 S lambs for each breed. The colour and the reflectance spectrum of different fat tissues were measured. The FS affected weights of all fat tissues and all colour parameters of perirenal and subcutaneous fat (P ≤ 0.01); it almost affected redness and yellowness of caudal fat (P ≤ 0.05; P ≤ 0.01). In all adipose tissues, lightness was higher and both redness and yellowness were lower for S lambs than P lambs. The breed affected weight, lightness and redness of perirenal fat and weight and redness of subcutaneous fat with significant interaction with FS for subcutaneous fat data. To discriminate P lambs from S lambs, the reflectance spectrum of perirenal, subcutaneous and caudal fat at wavelengths between 450 and 510 nm (Method 1, M1) or at wavelengths between 400 and 700 nm using partial least squares discriminative analysis as a classification method (Method 2, M2) were used. M2 yielded to a higher proportion of correctly classified lambs compared with M1 (P = 0.001). The proportion of correctly classified lambs using M2 was 76.4, 75.0 and 80.0% for perirenal, subcutaneous and caudal fat for P lambs and 83.3, 76.4 and 100.0% for S lambs. Despite lower reliability in comparisons to European researches, this study confirmed the efficiency of visible reflectance spectroscopy technique applied on perirenal fat in feeding systems authentication under North African conditions and spotted the caudal fat as a new support for better classification of fat-tailed breeds.     

Reducing the level of nutrition of twin-bearing ewes during mid to late pregnancy produces leaner prime lambs at slaughter

The Australian prime lamb industry is seeking to improve lean meat yield (LMY) as a means to increasing efficiency and profitability across the whole value chain. The LMY of prime lambs is affected by genetics and on-farm nutrition from birth to slaughter and is the total muscle weight relative to the total carcass weight. Under the production conditions of south eastern Australia, many ewe flocks experience a moderate reduction in nutrition in mid to late pregnancy due to a decrease in pasture availability and quality. Correcting nutritional deficits throughout gestation requires the feeding of supplements. This enables the pregnant ewe to meet condition score (CS) targets at lambing. However, limited resources on farm often mean it is difficult to effectively manage nutritional supplementation of the pregnant ewe flock. The impact of reduced ewe nutrition in mid to late pregnancy on the body composition of finishing lambs and subsequent carcass composition remains unknown. This study investigated the effect of moderately reducing ewe nutrition in mid to late gestation on the body composition of finishing lambs and carcass composition at slaughter on a commercial scale. Multiple born lambs to CS2.5 target ewes were lighter at birth and weaning, had lower feedlot entry and exit weights with lower pre-slaughter and carcass weights compared with CS3.0 and CS3.5 target ewes. These lambs also had significantly lower eye muscle and fat depth when measured by ultrasound prior to slaughter and carcass subcutaneous fat depth measured 110 mm from the spine along the 12th rib (GR 12th) and at the C-site (C-fat). Although carcasses were ~5% lighter, results showed that male progeny born to ewes with reduced nutrition from day 50 gestation to a target CS2.5 at lambing had a higher percentage of lean tissue mass as measured by dual energy X-ray absorptiometry and a lower percentage of fat during finishing and at slaughter, with the multiple born progeny from CS3.0 and CS3.5 target ewes being similar. These data suggest lambs produced from multiple bearing ewes that have had a moderate reduction in nutrition during pregnancy are less mature. This effect was also independent of lamb finishing system. The 5% reduction in carcass weight observed in this study would have commercially relevant consequences for prime lamb producers, despite a small gain in LMY.