F1 Lambs Research Articles

Myostatin mutation (g+6723G > A) introgression: comparative analysis of growth, slaughter, and carcass traits in Texel, Pırlak, and their crosses (F1 and BC1)

Abstract. This study was carried out to examine the effect of myostatin mutation on growth, body measurements, Musculus longissimus dorsi (MLD) values, and carcass characteristics in crossbred generations as well as introgression from Texel to Pırlak. This research was conducted on 105 F1, 94 myostatin-carrying BC1, 53 non-carrying BC1 lambs, and pure Pırlak and Texel lambs born during the same period. It was determined that the effects of factors such as genotype, sex, birth type, birth month, and dam age were significant (P< 0.05) for the growth characteristics of lambs. The birth weights, daily live weight gains and weaning weights in F1, myostatin-carrying BC1, and non-carrying BC1 lambs were 4.10, 4.45, and 4.39, 0.21252, 0.22176, and 0.20964, as well as 35.51, 33.18, and 33.47 kg, respectively. It was detected that Texel and myostatin-carrying BC1 lambs were significantly (P< 0.05) higher than Pırlak and non-carrying BC1 lambs for the MLD area at weaning. Additionally, the rump width, chest circumference, and MLD depth of lambs carrying myostatin mutation were significantly greater than Pırlak lambs. Six-month live weight means of Pırlak, Texel, and myostatin-carrying BC1 lambs were found as 39.45, 37.22, and 39.06 kg, respectively. Myostatin-carrying BC1 lambs had a superiority to Pırlak lambs in terms of muscle conformation and fatness of the hind leg. As a result, myostatin-carrying BC1 lambs were significantly found to have a better MLD area than non-carrying BC1 lambs, indicating a myostatin mutation (g+6723G > A) effect. It was concluded that the growth and carcass characteristics of Pırlak lambs may be improved by introgression of myostatin mutation.

Haematological parameters and production characteristics of novel Romanov × Hissar crossbred sheep adapted to European steppe climate

The study presented some haematological parameters and production characteristics of novel crossbred Romanov × Hissar and purebred Romanov sheep. A number of biochemical and haematological tests were performed to assess the level of adaptation of F1 crossbred progeny to local rearing conditions and evaluate its potential economic benefits for industrial production. The newly created crossbreed demonstrated significant increase in carcass production characteristics, with pre-slaughter weight increased by 29.2%, slaughter weight - by 39.7%, cooled carcass weight - by 40.5% and total yield ‒ by 8.2% compared to Romanov purebreed. The meat quality was also increased: fat content remained at the same level (6.6-6.8%), carcasses of F1 crossbreed lambs had higher relative weight of muscle tissue (78.8% vs. 73.3%), increased content of the 1st grade meat (94.6% vs. 91.6%), and higher caloric value of the meat (by 8.7%) compared to the parent purebreeds. An increased erythrocyte (by 3.1%) and leukocyte (by 6.45%) count was noted in the F1 rams. Haemoglobin level in F1 lambs was increased by 4.2%. Protein metabolism parameters were improved: blood serum total protein level ‒ by 11.2%, albumin ‒ by 11.4%, globulin ‒ by 10.4%, suggesting intensified protein metabolism in F1 lambs; this was also evidenced by the increased activities of aspartate transaminase (by 3.9%) and alanine transaminase (by 16.6%) in F1 lambs over Romanov purebred animals. Blood serum of crossbred lambs had higher bactericidal (by 1.92%), lysozyme (by 3.53%), and phagocytic activity. The increased haematological and biochemical parameters and enhanced antibacterial properties of serum indicate the enhanced metabolic activity in F1 crossbreed sheep and underlay the improved meat production parameters. Obtained results demonstrate increased adaptation of the novel crossbred to industrial rearing conditions and local microclimate of steppe zone of Ukraine, which is undergoing gradual aridization.

Effects of Sheep Sires on Muscle Fiber Characteristics, Fatty Acid Composition and Volatile Flavor Compounds in F1 Crossbred Lambs.

Crossbreeding significantly improves meat production performance in sheep; however, whether hybridization changes the meat quality characteristics of lambs is uncertain. We analyzed the effects of three different hybrid sires on muscle fiber characteristics (MFCs), fatty acid composition (FAC), and volatile flavor compounds (VFCs) in lambs under identical feeding conditions. Compared with those of purebred lambs, the muscle fiber diameter and cross-sectional areas of the crossbred lambs were significantly decreased (p < 0.05), and the collagen fiber content was significantly increased (p < 0.05). The numbers and area ratios of the fast and slow muscle fibers did not significantly differ between the purebred and crossbred lambs, but the expressions of four MyHC gene types differed significantly (p < 0.05). Twenty-three fatty acids were identified in both the purebred and crossbred lambs, of which thirteen were differentially expressed (p < 0.05). Saturated fatty acid (SFA) contents in the crossbred lambs were significantly increased (p < 0.05), whereas the monounsaturated fatty acid content was significantly decreased (p < 0.05). Polyunsaturated fatty acid/SFA and n-6/n-3 ratios were significantly lower in the crossbred lambs than in the purebred lambs (p < 0.05). Twenty-five VFCs were identified among the three hybrids, and aldehydes were the main VFCs. Eleven VFCs were differentially expressed in the crossbred lambs (p < 0.05). Hybrid sires affected the MFCs, FAC, and VFCs of the F1 lambs, thus providing a reference for high-quality mutton production.

Cardiovascular consequences of maternal obesity throughout the lifespan in first generation sheep.

Obesity continues to be a significant global health issue and contributes to a variety of comorbidities and disease states. Importantly, obesity contributes to adverse cardiovascular health outcomes, which is the leading cause of death worldwide. Further, maternal obesity during gestation has been shown to predispose offspring to adverse phenotypic outcomes, specifically cardiovascular outcomes. Therefore, we hypothesized that diet-induced obesity during gestation would result in adverse cardiovascular phenotypes in first-generation offspring that would have functional consequences in juvenile and advanced ages. Multiparous Rambouillet/Columbia cross ewes (F0) were fed a highly palatable, pelleted diet at either 100% (CON), or 150% (OB) of National Research Council recommendations from 60 days prior to conception, until necropsy at d 135 (90%) of gestation (CON: n = 5, OB: n = 6), or through term for lambs (F1: 2.5 mo. old; CON: n = 9, OB: n = 6) and ewes (F1:9 years old; CON: n = 5, OB: n = 8). Paraffin-embedded fetal aorta section staining revealed increased collagen:elastin ratio and greater aortic wall thickness in OBF1 fetuses. Invasive auricular blood pressure recordings revealed elevated systolic blood pressure in OBF1 lambs, but no differences in diastolic pressure. In aged F1 ewes, systolic and diastolic blood pressures were reduced in OBF1 relative to CONF1. Echocardiography revealed no treatment differences in F1 lambs, but F1 ewes show tendencies for increased end systolic volume and decreased stroke volume, and markedly reduced ejection fraction. Therefore, we conclude that maternal obesity programs altered cardiovascular development that results in a hypertensive state in OBF1 lambs. Increased cardiac workload resulting from early life hypertension precedes the failure of the heart to maintain function later in life.

Marker-assisted introgression of myostatin from Texel to Ramlıç sheep: Growth and real-time ultrasound carcass traits in F1 and BC1 lambs

The aim of the study was to evaluate live weights, body measurements, and real-time ultrasound carcass traits of F1 and BC1 genotypes in a marker assisted introgression (MAI) process. Effects of some factors on live weight and body measurements including ultrasonographic assessments in Musculus longissimus dorsi (MLD) were investigated at the F1 (n=51) and BC1 (n=99) cross lambs born in 2015 – 2017 period. Variance analysis showed that genotype had significant (P < 0.001) effect on pre- and post-weaning growth characteristics. The birth type had significant (P < 0.05) effect on pre- and post-weaning growth traits. Live weights at twelve months of age were higher in heavier born lambs. The growth performance of F1 lambs was between Texel and Ramlıç. Myostatin heterozygous BC1 lambs had been potentially heavier than the non-carriers and pure Texel. MLD depth and area were also statistically higher (P < 0.05) in BC1 lambs carrying myostatin than non - carriers. As a result, the beginning phase of introgression processes implemented was found to be successful

The Awassi sire can be used to crossbred with low-productive Tikur local ewes to produce export-marketable weight at yearling under farmer's management in the Ethiopian highlands

We conducted a community-based sheep cross breeding project in Ethiopia with exotic Awassi crossbred rams and less productive indigenous Tikur ewes. Fifty-five Awassi crossbred rams having 46,48, 56 and 65% Awassi blood levels were purchased and distributed to participating eighty-four farmers which had 2884 breeding ewes. The overall least square mean weights for F1 and F2 generation lambs at birth, day 90, 180, 270 and yearling weight were 3.10±0.01, 13.04±0.07, 16.95±0.08, 20.84±0.11 and 24.42±0.14 kg, respectively. Body weight traits were significantly affected by lambing year for birth weight (p < 0.05), 180-day weight (P < 0.05), 270-day weight (P < 0.001) and 360 day (yearling) weight (P < 0.001) but no effect (p > 0.05) was noted for 90-day weight (weaning weight). Season of lambing had significant effect (P < 0.01) only for birth weight. There was a significant difference (P < 0.001) among the different villages for birth weight, and for day 90, 180, 270 and 360 body weights. The study showed that crossing Awassi crossbred rams with Tikur ewes can improve birth weight by 71.27%, 90-day weight by 76.78%, 180-day weight by 63.45% and yearling weight by 76.06% under farmer management practices. Results revealed that crossing Awassi crossbred rams with blood level of 56% and above with local ewes resulted in superior progenies that can fulfill export live weight standard of 25 kg at yearling weight. In the future of Awassi-Tikur sheep farming must focus on feed supplementation strategies and on establishing cooperatives for farmers to improve their livelihoods.

A variant associated to IGF-1 mRNA and protein expression in sheep

The insulin-like growth factor-1 (IGF-1), a key hormone in muscle development was investigated for single-nucleotide polymorphisms (SNPs) upstream of the IGF-1 gene and their effects upon its cognate mRNA and hormone levels in sheep. A 70 d feeding trial was conducted with 22 F1 (Dorper × Pelibuey) lambs, individually allocated and fed a diet with a forage-to-concentrate ratio of 36:64 and 17% crude protein. Sequence analyses of 265 bp upstream the IGF-1 gene revealed the variant NC_040254.1:g.[184028491G > C;184028493G > A]. These SNPs generate alleles A and B, with frequencies of 0.66 and 0.34 in F1 lambs and of 0.73 and 0.27 in 81 pure Dorper lambs, respectively. Females were grouped by genotype AA, AB and BB (n = 3). IGF-1 hormone concentrations at 14, 42 and 70 d were higher (p < 0.05) in AA lambs compared to AB + BB lambs. The IGF-1 mRNA level was 2.6-fold higher in AA animals (n = 5, p < 0.05) than in AB + BB lambs (n = 7). A DNA binding site for the Inhibitor of Growth family member 4 (ING4) was found in allele B but not in allele A, which could explain the lower mRNA and hormone expression levels for AB + BB animals. The variant reported here appears to function as an eQTL with a negative effect on the level of IGF-1.

Poisoning by Brachiaria spp. in various lamb breeds at increasing levels of supplementation during growth

ABSTRACT: The study evaluate the frequency of poisoning by Brachiaria spp. at the rearing, growth and termination stages in various lamb breeds at increasing supplementation levels. Forty-five lambs were used in the growth phase in pastures of Brachiaria spp. with a history of having induced poisoning. The lambs were distributed in nutritional treatments: lambs receiving mineral supplementation (MS), energy/protein supplementation (EPS) at 0.8% of body weight (bw), EPS at 1.6% bw and EPS at 2.4% bw. The lambs were allotted two flocks (F1 and F2) of 21 and 24 lambs each. Clinical signs of poisoning were observed in all treatments. All MS lambs died. The frequency of poisoning were highest in the 0.8% EPS and 1.6% EPS treatments. All lambs in the 2.4% EPS treatment recovered. F1 lambs had a higher frequency of poisoning than F2 lambs regardless of nutritional treatment. Morbidity rates for the F1 and F2 lambs were 52.3 and 16.7%, respectively. Supplementation was not sufficient to decrease the frequency of poisoning in lambs at the termination stage, which was dependent on the genetic origin of the lambs. EPS of 2.4% bw treatment, was an efficient nutritional strategy to minimize the effects of poisoning in lambs fed on Brachiaria spp.

Evaluation of the in vivo anthelmintic properties of Mitragyna inermis (Willd.) as a livestock dewormer against parasitic hematophagous worm Haemonchus contortus infections in different breeds of lambs.

Gastrointestinal (GI) nematodes remain a major constraint on livestock production throughout the world. This study assessed the in vivo efficacy of the powder of Mitragyna inermis leaves in three breeds of lambs, namely, West African dwarf lambs (WAD), West African long-legged lambs (WALL), and F1 lambs (cross of a WALL ram with a WAD ewe), artificially infected with 3000 L3s of Haemonchus contortus in a controlled experiment. Fecal sample examination, serological analysis, and necropsy were carried out to determine the egg count, worm burden, and worm fecundity reduction. A dose of 3.2g/kg body weight (BW) M. inermis was administered per the oral route for three consecutive days and repeated 2weeks later. Compared with the control, the powder of M. inermis leaves (> 60%) and albendazole (100%) significantly reduced (p < 0.01) fecal egg counts (FECs) in the three breeds of lambs. The posttreatment reduction in FECs fluctuated from 56.99 to 78.75% for WAD lambs, 38.39 to 66.39% for WALL lambs, and 35.55 to 63.11% for F1 lambs (WALL × WAD). Significant differences (p < 0.05) were observed in packed cell volume values before and after infection. M. inermis reduced the egg-laying capacity of female adult worms by up to 60% and eliminated more than 80% of the adult worms of H. contortus in lambs. Furthermore, albendazole reduced the worm count and fecundity of female worms by greater amounts than M. inermis (100%). The findings of this study showed that M. inermis is a good source of bioactive compounds for drug development. According to this result, a 3.2g/kg BW dose of the plant could be applied for the control of GI nematodes in small ruminants.

Rambouillet and Romanov reciprocal breed effects on survival and growth traits of F1 lambs and on reproductive traits of F1 ewes.

Objectives were to estimate reciprocal effects of Romanov and Rambouillet breeds on survival, growth, and reproductive traits of F1 progeny and direct breed effects (Suffolk and Composite - ½ Columbia, ¼ Hampshire, and ¼ Suffolk) on survival and growth traits of the subsequent terminally sired lambs. Mature Rambouillet ewes (n = 243) were exposed to 20 Romanov rams over two seasons producing 621 lambs for evaluation of growth and survival traits with 274 F1 ewes being evaluated for reproduction traits through 4 yr of age. Similarly, mature Romanov ewes (n = 116) were exposed to 20 Rambouillet rams producing 601 lambs for evaluation of growth and survival traits with 176 F1 ewes being evaluated for reproduction traits through 4 yr of age. A total of 433 of those F1 ewes produced 3,431 lambs (1,552 litters) from 1,634 exposures to terminal sires over 4 yr. Terminal sires consisted of 38 Suffolk and 44 Composite rams. Reciprocal crossbred ewe lambs were produced from dramatically different uterine and neonatal environments, with litter size at birth from Romanov dams exceeding those from Rambouillet dams by 1.52 lambs (P < 0.001) and birth weight of lambs from Romanov dams averaged 3.41 kg compared with 4.26 kg from Rambouillet dams. Differences in BW were still evident at 140 d (P < 0.001) for dam-reared lambs. However, reciprocal ewe first breeding BW of both types were similar (P = 0.38). Minimal differences were observed in performance of reciprocal cross ewes through 4 yr for productivity, longevity, or progeny growth and survival. One exception was BW at 140 d where an interaction of dam breed with terminal sire breed reached significance for both dam-reared (P = 0.05) and nursery-reared (P = 0.02) lambs. This interaction was due to the lower weight of Composite-sired lambs out of reciprocal cross ewes born from Rambouillet dams. Composite rams increased number born (P < 0.01) and number weaned (P < 0.05) of the reciprocal cross ewes. Suffolk rams increased (P < 0.001) BW and growth rates from birth to 140 d of terminal progeny. Thus, there were little cumulative differences accrued over the 4 yr and no differences were detected for cumulative kilogram of lamb generated at 140 d per ewe exposed. The practical outcome of this evaluation was that performance levels of both types of Romanov crossbred ewes was similar allowing the industry to produce the desired crossbred ewes without needing large purebred ewe flocks of the less numerous Romanov breed.

Genetic parameter estimates and targeted association analyses of growth, carcass, and meat quality traits in German Merinoland and Merinoland-cross lambs.

In this study, genetic parameters of nine growth, carcass, and meat quality (MQ) traits were estimated, and targeted association studies were conducted using mixed models. Phenotypic information was collected on 1,599 lambs, including both purebred Merinoland (ML) animals and five different F1 crosses. The F1 lambs were produced by mating rams of the meat-type breeds Charollais, Ile de France, German Blackheaded Mutton (Deutsches Schwarzköpfiges Fleischschaf), Suffolk, and Texel with ML ewes. Between four and six sires were used per sire breed. In total, 29 sires and 298 purebred ML sheep were genotyped with the Illumina OvineSNP50 BeadChip. All F1 individuals were genotyped for 289 SNPs located on the chromosomes 1, 2, 3, 18, and 21. These SNPs were used to impute SNPs on five chromosomes of the Illumina Ovine chip in the F1 individuals. Several Bonferroni-corrected significant associations were identified for shoulder width. A number of additional significant associations were found for other traits. Genetic parameters were estimated and single-marker association analyses were performed with breed-specific effects. Moderate heritability estimates were found for average daily gain (0.23), kidney fat weight (0.19), carcass length (0.15), shoulder width (0.33), subcutaneous fat thickness (0.22), and cutlet area (0.36). While heritability for cooking loss was found to be low (0.07), shear force (0.17) and dressing percentage (0.20) showed moderate heritability, and thus might be candidate traits to be included in the selection index in the population. In general, low phenotypic and low or moderate genetic correlations were detected between the traits.

Growth and reproductive traits of purebred and crossbred Romanov lambs in Eastern Anatolia

The performance of purebred Romanov (R) lambs and crossbred lambs of Romanov and Morkaraman (M) breeding were compared under a semi-intensive production system. The M breed is a fat-tailed breed native to Eastern Anatolia, Turkey. Analyses were conducted on data from 168 lambs produced from R and M ewes through laparoscopic artificial insemination (LAI) with the semen of pure R and F1 RxM rams. Pure R, F1 (RxM, ½ R), and ¼ R (RxM x M backcross) lambs were produced. The F1 and ¼ R lambs had heavier (P < 0.05) birth weights than R lambs while F1 and R lambs had heavier (P < 0.05) weaning weights than ¼ R lambs. The three groups of lambs differed (P < 0.05) from each other for age of puberty in males and females where with R lambs were the youngest, F1 lambs were intermediate, and ¼ R lambs were the oldest. The percentage of ewe lambs that exhibited estrus within one year of age was higher (P < 0.01) for R (100%) and F1 (67%) lambs than for ¼ R lambs (43%). In conclusion, improvement in growth and early reproductive traits can be obtained from crossbreeding the fat-tailed Morkaraman breed with the Romanov breed.

Multigenerational impact of maternal overnutrition/obesity in the sheep on the neonatal leptin surge in granddaughters.

Background/ObjectivesWe have reported that maternal overnutrition/obesity (OB) in sheep resulting from feeding 150% of National Research Council (NRC) requirements throughout gestation, leads to maternal hyperglycemia and hyperinsulinemia. Further, newborn lambs born to OB vs. control-fed (CON, 100% of NRC) ewes exhibited greater adiposity, increased blood cortisol, insulin and glucose and the elimination of the postnatal leptin spike seen in lambs born to CON ewes. This early postnatal leptin peak is necessary for development of hypothalamic circuits which program appetite in later life. This study evaluated the multigenerational impact of OB on insulin:glucose dynamics of mature female F1 offspring fed only to requirements throughout gestation, and on their lambs (F2 generation).Design and MethodsAdult F1 female offspring born to OB (n=10) or CON (n=7) ewes were utilized. All F1 ewes were subjected to a glucose tolerance test at midgestation and late gestation. Jugular blood was obtained from F2 lambs at birth (day 1) through postnatal day 11, and plasma glucose, insulin, cortisol and leptin concentrations determined. Dual Energy X-ray Absorptiometry (DEXA) was utilized to determine bone mineral density (BMD), bone mineral content (BMC), lean tissue mass, and fat tissue mass.ResultsFasted blood glucose and insulin concentrations were greater (P < 0.05) in OBF1 than CONF1 ewes at mid- and late gestation. Further, after glucose infusion, both glucose and insulin concentrations remained higher in OBF1 ewes (P < 0.05) than CONF1 ewes demonstrating greater insulin resistance. Blood concentrations of glucose, insulin, and cortisol, and adiposity were higher (P < 0.01) in OBF2 lambs than CONF2 lambs at birth. Importantly, OBF2 lambs failed to exhibit the early postnatal leptin peak exhibited by CONF2 lambs.ConclusionsThese data suggest that these OBF2 lambs are predisposed to exhibit the same metabolic alterations as their mothers, suggesting a multi-generational programming effect.

Comparative evaluation of growth and carcass traits of indigenous and crossbred (Dorper × Indigenous) Ethiopian Sheep

An experiment was conducted to evaluate growth and carcass traits of indigenous (Blackhead Ogaden [B1] & Hararghe Highland [B2]) and crossbred (Dorper×B1 [B3] & Dorper×B2 [B4]) F1 lambs under different feeding regimens. The feeding regimens constituted feeding hay ad libtum supplemented with 150g/head/day concentrate mix [D1] and hay ad libtum supplemented 350g/head/day concentrate mix [D2]. The experiment was arranged as a 4×2 factorial (4 breeds and 2 levels of nutrition) and laid out completely at random. Hararghe Highland lambs had the highest (P<0.01) TDMI (90.0±1.4), gDM/kgW0.75 compared with B4. Lambs fed D2 had higher TDMI (P<0.0001), TDMI per metabolic body weight (P<0.01) than lambs fed D1. Dorper×Hararghe Highland had greater average daily weight gain (69.4±4.1g), empty body weight, hot (12.9±0.5) and cold carcass weight (12.6±0.5kg) than did both B1 and B2. However, weight loss after chilling was higher (5.7±0.3%) in pure Blackhead Ogaden compared with rest of lamb breeds.This study leads to the conclusion that crossing B2 with Dorper improved feed utilization, growth rate and carcass parameters, but crossing B1 with Dorper provided little benefit since the B1 tend to perform similar to the crosses in some economically important traits.

Carcass Measurement, Conformation and Composition of Indigenous and Crossbred (Dorper x Indigenous) F1 Sheep

A study was conducted to evaluate carcass measurement, conformation and composition of local (Blackhead Ogaden (B1) and Hararghe highland (B2)) and cross breed (Dorper x Blackhead Ogaden (B3) and Dorper x Hararghe highland (B4)) F1 lambs at two levels of concentrate supplement. The two diets were native grass hay ad libtum + 150 g concentrate mix (D1 (low level), Wheat Bran (WB) and Noug Seed Cake (NSC), at a ratio of 2:1) and native grass hay ad libtum + 350 g concentrate mix (D2, high level) in stal l feeding. The experiment was arranged in a completely randomized design in a factorial arrangement (four breeds and two levels of diet). B4 had (p<0.05) longer hind leg posterior buttock circumference, thoracic circumference and chest width than B2, but did not differ from B1. Lambs fed high level of concentrat e supplement have longer leg length wider posterior and anterior buttock circumference, buttock and chest width than low level concentrate supplemented groups. The fat content of both cross breeds is lowe r compared to pure Blackhead Ogaden. Leaner carcass was harvested from lambs consumed low level of concentrate supplement compared to lambs consumed high level of concentrate supplement. Result suggests that crossing Dorper with pure Hararghe highland improved carcass measurement and conformation. However, pure Blackhead Ogaden tended to perform similar to crosses in some parameters measured indicating the possibility of improving this breed without cross breeding. The result also noted that good nutrient supply is necessary for better carcass measurement and conformation.

Effects of crossbreeding Hungarian Merino sheep with Suffolk and Ile de France on carcass traits

Abstract. In this examination, Hungarian Merino (ram n=30, ewe n=30), Hungarian Merino × Ile de France F1, and Hungarian Merino × Suffolk F1 (ram n=15, ewe n=15) lambs were used to evaluate the effect of crossbreeding on carcass characteristics and composition. We examined fattening performances and the following carcass traits: dressing percentage, weight of valuable carcass cuts, percentage of valuable meat, bone to meat ratio, and as well as meat conformation and fat cover (S/EUROP grading). In the present investigation, the weight at slaughter was fixed between 31–32 kg approximately, thus ensuring, weight would not affect carcass composition. Standardizing carcass weight allowed us to spot differences due to genotype and gender. The best results of fattening performance showed the Hungarian Merino × Ile de France F1 lambs (358 g/day). The tested crossed genotypes had not greatly influence dressing percentage and warm carcass weight, but the best percentage valuable carcass cuts had Hungarian Merino × Suffolk F1 (83.37 %). The best percentage of valuable meat presented (77.76 %) the Hungarian Merino × Ile de France F1 lambs. The best meat conformation and fat covered showed the Hungarian Merino × Suffolk F1 lambs. Hungarian Merinos showed less favourable results. To the summarising, the Suffolk and Ile de France improved the Hungarian Merino’s fattening performance, slaughter value and ability of market over 30 kg live weight, therefore there were both breeds suggest with crossing.

Growth and carcass characteristics of crossbred progeny from lean-tailed and fat-tailed sheep breeds

The performance of two fat-tailed sheep breeds, Chaal and Zandi, and their F1 and R1 crossbred lambs from a lean-tailed breed, Zel, was compared. The weaned lambs from the Chaal and Zandi groups were finished over periods of 105 and 90 days, respectively, and body weight gain and feed consumption were recorded. Forty six male and female lambs from the six finishing groups were slaughtered. The weights of blood, internal organs, intestines before and after removal of digesta, head, feet, pelt and carcasses were recorded. The left sides of the carcasses were cut into six pieces. Individual joints were dissected into lean meat, bone, subcutaneous fat (SCF), intramuscular fat (IMF) and trimmings, and weighed separately. The fat surrounding the intestine and kidney was weighed and considered as internal fat. All the soft tissue (lean meat and fat) of the left sides of the carcasses was ground and representative samples were taken for chemical analyses. The differences of eye muscle ( Longissimis dorsi ) area (cm2), and protein and bone percentages were not significant between both breeds and their crosses. In the R1 the fat-tail percentage was less than in the F1 and pure lambs of both breeds. In contrast, the SCF and IMF percentages were higher in all crossbred combinations. The internal fat percentages in crossbreds were higher, and in the Chaal group differed significantly from that of the pure lambs. The SCF/IMF ratio in the R1 lambs was lower than in the pure breds. This difference for Chaal crossbreds was significant. The lower ratio of SCF/IMF and the higher internal fat of crossbred lambs compared to pure breds showed that carcass quality of the crossbred was inferior compared to the pure bred lambs in terms of fat distribution in the body. Keywords: Sheep, fat-tail, backcross, Chaal, Zandi, Zel South African Journal of Animal Science Vol. 37 (1) 2007: pp. 51-56

Genetic type, sex, age at slaughter and feeding system effects on carcass and cut composition in lambs

The aim of this research was to estimate the effects of grading up of Gentile di Puglia with Ile de France on carcass traits and the composition of cuts in lambs slaughtered at 35 and 54 days of age. Data was collected on 223 lambs of both sexes, single birth, belonging to the genetic types Ile de France (IF), Gentile di Puglia (GP) and the result of grading up of the latter with Ile de France rams (F1 and F2). About half of the subjects were fed with maternal milk (natural feeding) while the others were fed on a milk replacer (artificial feeding). The lambs of both groups were randomly allocated in two slaughter age subgroups: 35 and 56 days. The results of statistical analysis showed that the considered factors of variation significantly influences the weight of the carcass, the percentage of cuts and their composition. Most of the variation was due to the age and to the feeding system. The F2 lambs on average had the heaviest carcass and sides, the GP had the highest percentage of fore quarter while the IF had the highest percentage of back quarter. Furthermore F1 lambs did not show any heterotic effect compared with both parental breeds, while F2 breeds showed better performance. The carcass of the males resulted heavier than the females, with a lower percentage of dissectible fat at the neck, brisket, shoulder and leg and a higher percentage of meat in the shoulder cut. The lambs slaughtered at 35 days of age showed a higher incidence of kidney, shoulder and leg weight, while at 56 days furnished a higher percentage of kidney fat, brisket and loin weight. The artificially fed lambs furnished a lighter carcass and neck and shoulder cuts than naturally fed lambs, less kidney fat and a higher percentage of kidney, rib and loin weight. The employment of artificial feeding permitted a higher percentage of lean and less dissectible fat as well as a higher lean/bone ratio. These results show that Ile de France rams crossbreed with Gentile di Puglia determine good productive performance if the lambs derive from the F2 crossbreed and are artificially fed and slaughtered at 56 days of age.

Genetic relationships among objectively and subjectively assessed traits measured on crossbred (Mule) lambs

AbstractSheep farming in the UK is characterized by a crossbreeding system where ‘Longwool’ sire breeds are mated with hill dam breeds, with the crossbred (F1) ewe lambs retained for mating to terminal sires. The F1 wether and terminal-sire cross lambs are marketed for meat. At selection, F1 females are typically assessed visually for type traits relevant to dam lines, and these traits could be considered as goal traits. Their offspring and their male sibs derive their value from carcass traits. This study investigated the genetic relationships between type (subjective) and carcass (objective) traits in F1 lambs, and their potential impact on genetic improvement within this production system. Bluefaced Leicester rams were crossed with Scottish Blackface and Hardy Speckled Face ewes to produce F1 (‘Mule’) lambs. The wether lambs (no.=2197) were selected for slaughter at a target condition (a carcass fat score of 2/3L) and a number of live and carcass traits were measured. Carcass dissection data were collected on approximately one-third of these wether lambs. The ewe lambs (no.=2423) were measured for similar live traits but at a fixed age (195±5·5 days). In addition, they were subjectively assessed for a number of functional and type traits. Genetic parameters among these traits were then estimated. Heritabilities for the ewe traits were generally moderate (0·18 to 0·31) and genetic correlations between the traits were variable, with some moderate to high correlations (favourable in direction) of growth/carcass traits with overall type traits. Live weight at slaughter in wethers was highly correlated to live weight at constant age in ewes (r=0·72). In the wethers, live, cold carcass and lean weight had moderately high heritabilities (between 0·26 and 0·46), and were positively correlated with slaughter age (≥0·79). However, age at slaughter in wethers was highly negatively correlated with growth/carcass and overall type traits in ewes (between −0·45 and −0·97), perhaps reflecting differences in maturity in lambs measured at a target fatness versus age. The correlations of most other type traits in ewes with wether traits were non-significant. These results show that the subjectively assessed type traits (at least as measured in this study) will not deteriorate, and some will in fact be improved, in a selection programme aiming to improve carcass merit.

Effect of electrical stimulation and other genetic and environmental factors on colour of lamb meat

ReferencesThe research aimed to assess the effect of electrical stimulation, breed, sex, age at slaughter and rearing system on some colorimetric characteristics measured on the muscles Longissimus dorsi (LD), Gluteobiceps (Gb), Semimembranosus (Sm) and Rectus femoris (RF) of lambs belonging to the genetic types Gentile di Puglia (GP), Ile de France (IF) and the cross-breeds F1, F2 and F3. The IF lambs provided meat with the highest value of hue and lightness and the lowest chroma and redness. The F1 lambs showed the highest values of redness while the F2 crossbreed significantly differed from the F1 for the lowest value of lightness, yellowness and chroma. The F3 crossbreed revealed similar behaviour to the paternal breed for lightness, yellowness and pH. No differences between sexes were observed. The lambs slaughtered at 56 days showed higher a* values, while b* and hue were on average higher in younger lambs (35 days). The lambs reared with maternal milk, in comparison with the artificially reared ones (reconstituted milk), provided meat with higher a*, b* and chroma. The electrical stimulation made it possible to achieve lower lightness and pH and higher b* and chroma values. Among the considered muscles, RF provided the lightest meat; Sm showed the highest values of b*, hue and chroma; LD provided the “darkest” meat and the lowest values of b* and hue; Gb produced lower a* value than muscles LD, RF and Sm.