Mutton Merino Research Articles

Genome-wide association research on the reproductive traits of Qianhua Mutton Merino sheep.

Qianhua Mutton Merino sheep is a new breed of meat wool sheep cultivated independently in China. In 2018, it was approved by the state and brought into the national list of livestock and poultry genetic resources. Qianhua Mutton Merino sheep have the common characteristics of typical meat livestock varieties with rapid growth and development in the early stage and high meat production performance. The objective of this research is to investigate the Genome-wide association of the reproductive traits of Qianhua Mutton Merino sheep. Qianhua Mutton Merino sheep from the breeding core group were selected as the research object, genome-wide association analysis was conducted on genes associated with the reproductive traits (singleton or twins, birth weight, age [in days] for sexual maturity, weaning weight, and daily gain from birth to weaning) of Qianhua mutton merino. Our study findings showed that 151 loci of single-nucleotide polymorphisms (SNPs) were detected, among which 3 SNPs related to birth weight and weaning weight occupied a significant portion of the wide genome. The candidate genes preliminarily obtained were SYNE1, SLC12A4, BMP2K, CAMK2D, IMMP2L, DMD, and BCL2. We found 151 SNP loci for five traits related to reproduction (including singleton or twins, birth weight, age [in days] at sexual maturity, weaning weight, and daily weight gain from birth to weaning). The functions of these candidate genes were mainly enriched in nucleotide metabolism, metal ion binding, oxytocin signaling pathway, and neurotrophin signaling pathway.

Inbreeding Depression and Purging for Meat Performance Traits in German Sheep Breeds.

This study provides estimates on genetic parameters, inbreeding depression and purging for meat performance measures from 25 German sheep breeds. All German meat, merino sheep breeds and breeds of other breeding directions with a sufficient number of pedigree and performance data were included in this study. Phenotypic traits retrieved from the national database OviCap were evaluated: daily weight gain, meatiness score and ultrasound measurements for muscle and fat thickness. We employed animal models to estimate heritability, variance and covariance components for these meat performance traits as well as inbreeding depression and purging. The heritabilities, on average, reached estimates of 0.55, 0.34, 0.53 and 0.61 for daily weight gain, meatiness score and ultrasound measurements for muscle and fat thickness, respectively. We estimated the linear regression slopes for the individual rate of inbreeding, new and ancestral inbreeding, as well as the inbreeding coefficient and its interaction with the inbreeding coefficient of Ballou, employing animal models with non-genetic effects and the additive genetic effect of the animal. Across all breeds, inbreeding was only significant for daily weight gain, whereas for all other traits, estimates were not significant. Within sheep breeds, we found significant inbreeding depression for daily weight gain in German Mutton Merino and German Blackheaded Mutton as well as for the meatiness score in German Whiteheaded Mutton. Significant effects for purging, based on ancestral inbreeding and the interaction effect of the classical inbreeding coefficient with the inbreeding coefficient of Ballou, were not obvious either across or within any sheep breed. A 1% increase in inbreeding significantly decreased the phenotypic trait median of daily weight gain across all sheep breeds by 0.50% and 0.70% of phenotypic and genetic standard deviation, respectively. Purging effects due to ancestral inbreeding were not significant in any breed or across breeds. The results of this study may indicate that inbreeding depression may be more harmful in traits under stronger selection than in traits that exert low selection pressure. The results of this study demonstrate the different effects that result in meat performance traits due to inbreeding. With increasing rates of inbreeding and critical effective population sizes, selection intensity for breeding objectives has to be critically reviewed for each sheep breed. Inbreeding depression and purging should be evaluated in order to prevent a decrease in trait means due to inbreeding and to determine whether detrimental alleles are eliminated.

Association of SNPs within PTPN3 gene with wool production and growth traits in a dual-purpose sheep population

Protein tyrosine phosphatase non-receptor type 3 (PTPN3), a member of the membrane-associated non-receptor protein tyrosine phosphatase (PTP) family, plays significant roles in the cytoplasm and affects the development and growth of skin and hair. A recent study identified the PTPN3 as the potential gene related to sheep wool quality. To detect single-nucleotide polymorphisms (SNPs) of PTPN3 and elucidate its association with wool production and growth traits in fine wool sheep a total of 644 healthy SG (South African mutton merino♂ × Gansu alpine fine-wool sheep♀, SG) and SSG (South African mutton merino♂ × SG♀, SSG) hybrid sheep were selected. Pooled-DNA sequencing and SNPscan methods were used to scan and genotype SNPs within PTPN3. Association analyses between SNPs and wool production and growth traits were implemented. Consequently, the results revealed that PTPN3 has six SNPs (two missense mutations, one synonymous mutation, and three intron mutations), of which four loci (SNP2, SNP3, SNP4, and SNP5) were significantly positively correlated with growth and wool traits (p < 0.05). SNP4 was significantly (p < 0.05) linked with thigh wool length, and SNP6 was significantly (p < 0.05) associated with abdomen wool length. Moreover, one strongly linked SNP block was identified to be correlated with wool production and growth traits (body weight and body size). The significant SNPs founded by this study could serve as useful genetic markers for breeding fine-wool sheep.®

Growth performance and carcass characteristics of south african mutton merino fed diets with different levels of macadamia oil cake or baobab seed cake

This experiment was conducted to evaluate the effects of supplementing 10% or 15% of baobab seed cake (BSC) or macadamia oil cake (MOC) in fattening diets for lambs on feed intake, growth performance and carcass characteristics. Thirty-two lambs aged between 150 and 180 days were randomly allocated to 4 diets (10% MOC; 15% MOC; 10% BSC and 15% BSC diets) in an experiment arranged as a 2x2 factorial design and sex as a block. The results showed that there were significant protein source and inclusion level interactions on average daily feed intake, average daily gain, and total weight gain, warm and cold carcass mass. Males were significantly superior in all parameters except for feed conversion ratio, dressing percentage and rib-eye area. It was concluded that 10% MOC and 15% BSC can be incorporated in diets for fattening of growing South African Mutton Merino lambs without compromising on their growth performance and carcass characteristics.

Genetic diversity and population structure of South African smallholder farmer sheep breeds determined using the OvineSNP50 beadchip.

A population structure study was performed in South African ovine populations using the OvineSNP50 beadchip. Blood samples were obtained from 295 sheep of which 172 had been identified as smallholder Dorpers, 4 smallholder White Dorpers, 46 purebred Dorpers, 26 purebred South African Mutton Merinos and 47 purebred Namaqua Afrikaners. Blood from the latter three breeds were obtained from a resource flock maintained on the Nortier research farm. Genetic diversity was estimated using allelic richness (A r), observed heterozygosity (H o), expected heterozygosity (H e) and inbreeding coefficient (F). Population structure analysis was performed using fastSTRUCTURE to determine the breed composition of each genotyped individual. The Namaqua Afrikaner had the lowest H e of 0.280±0.18 while the H e of smallholder Dorper, Dorper and South African Mutton Merino did not differ and were 0.364±0.13, 0.332±0.16 and 0.329±0.17, respectively. The average inbreeding coefficient was highest for the pure breeds, Namaqua Afrikaner, Dorper and South African Mutton Merino compared to the average inbreeding coefficient for the smallholder Dorper population. The smallholder Dorper were introgressed with Namaqua Afrikaner, South African Mutton Merino and White Dorpers. Similarly, the smallholder Dorper population was more genetically diverse than the purebred Dorper, South African Mutton Merino and Namaqua Afrikaner from the research farm. The higher genetic diversity among the smallholder sheep may be advantageous for their fitness and can be used to facilitate selective breeding.

Effects of different dietary inclusion levels of macadamia oil cake on growth performance and carcass characteristics in South African mutton merino lambs.

Growth performance and carcass characteristics of South African mutton merino fed graded levels of macadamia oil cake were assessed. A total of 60 South African mutton merino lambs were used in the experiment (initial live weight 25.0 ± 0.45kg). Five diets with different inclusion levels of macadamia oil cake (MOC) were formulated: T1 (0% MOC, control), T2 (5% MOC), T3 (10% MOC), T4 (15% MOC) and T5 (20% MOC). Effects of inclusion level of MOC on average daily gain (ADG) and average daily feed intake (ADFI) were not significant (P > 0.05). Effects of inclusion levels of MOC on feed conversion ratio (FCR) of sheep were significant (P < 0.05). Highest proportion (71.2%) of sheep in the study had a carcass fat classification of 2, followed by a proportion of 17.3% sheep with a carcass fat classification of 3 and lastly 11.5% sheep had carcass fat classification of 4. Warm and cold carcass mass, chest circumference, carcass length and dressing percentage were higher in sheep fed on 5% MOC compared to other treatment diets (0, 10, 15 and 20% MOC) (P < 0.05). Fat rib eye had a greater area in sheep fed on 5% MOC (P < 0.05). It was concluded that 5% MOC provided the best results in terms of carcass characteristic measurements in sheep.

Genome-Wide Specific Selection in Three Domestic Sheep Breeds.

BackgroundCommercial sheep raised for mutton grow faster than traditional Chinese sheep breeds. Here, we aimed to evaluate genetic selection among three different types of sheep breed: two well-known commercial mutton breeds and one indigenous Chinese breed.ResultsWe first combined locus-specific branch lengths and di statistical methods to detect candidate regions targeted by selection in the three different populations. The results showed that the genetic distances reached at least medium divergence for each pairwise combination. We found these two methods were highly correlated, and identified many growth-related candidate genes undergoing artificial selection. For production traits, APOBR and FTO are associated with body mass index. For meat traits, ALDOA, STK32B and FAM190A are related to marbling. For reproduction traits, CCNB2 and SLC8A3 affect oocyte development. We also found two well-known genes, GHR (which affects meat production and quality) and EDAR (associated with hair thickness) were associated with German mutton merino sheep. Furthermore, four genes (POL, RPL7, MSL1 and SHISA9) were associated with pre-weaning gain in our previous genome-wide association study.ConclusionsOur results indicated that combine locus-specific branch lengths and di statistical approaches can reduce the searching ranges for specific selection. And we got many credible candidate genes which not only confirm the results of previous reports, but also provide a suite of novel candidate genes in defined breeds to guide hybridization breeding.

Estimations of genomic linkage disequilibrium and effective population sizes in three sheep populations

As one of the most important measures in population genetics, linkage disequilibrium (LD) is the basis of effective population size estimation, genomic selection, genome-wide association study and quantitative trait locus mapping. Here, we characterized the pattern of LD in three sheep populations (Sunite, German Mutton Merino, and Dorper) and subsequently estimated persistence of phase among them using the Illumina Ovine SNP50k Chip. In addition, we calculated the corresponding effective population sizes using the metric r2 estimated. The results showed that the extent of LD was highest in Dorpers, followed by German Mutton Merinos and Sunites. Average r2 values were 0.13, 0.20, and 0.22 at adjacent marker distances of 57.28, 59.01, and 59.93kb for Sunite, German Mutton Merino, and Dorper sheep, respectively. The average r2 values at the same genomic distance in German Mutton Merino and Dorper sheep were similar and higher than that in Sunite sheep, and the rate of LD decay over distance was faster than the rates in the other two sheep breeds. The correlation of phase for different breed comparisons ranged from 0.784 to 0.825. The effective population sizes in Sunite, German Mutton Merino, and Dorper sheep 7 generations ago were approximately 207, 74, and 67, respectively. We also detected a bottleneck in the effective population size for Sunite sheep that was consistent with the timing for the origin of the domestication of Chinese sheep. Our findings provide a theoretical reference for future genome marker-assisted evaluation and selection in sheep.

The effect of application of the FAMACHA© system on selected production parameters in sheep

Much research has gone into developing a sustainable management tool for haemonchosis, namely the FAMACHA© system, which has been validated by numerous studies worldwide. However, the financial implications on production of implementing this system have not been fully investigated in sheep previously. A trial was conducted on a farm comprising a flock of approximately 300 Mutton Merinos on which the FAMACHA© system was in use. Seventy five maiden and multiparous ewes were randomly allocated to the following three trial groups: (i) FAMACHA© in which ewes judged to be in categories 4 or 5 were dosed with levamisole HCl 2.5% (Nemasol NF, Intervet); (ii) Conventionally dosed in which all ewes were dosed every six weeks with levamisole HCl 2.5% (Nemasol NF, Intervet); (iii) Suppressively dosed in which all ewes were injected every six weeks with moxydectin 1%m/v (Cydectin, Bayer AH).There were no significant differences in body weight gains, FAMACHA© and body condition scores amongst the three treatment regimens for ewes that did not conceive. For those that became pregnant during the trial there was a significant difference when analysed by calendar date but not when analysed by reproductive stage. There were also no significant differences between trial groups in lamb birth weight and, after slow growers had been sold, the average daily gain of the lambs born to ewes in the trial. The cost of anthelmintics was considerably lower for the FAMACHA© group. In conclusion there were no significant differences in selected production parameters when using the FAMACHA© system as opposed to other methods of anthelmintic use in a Mutton Merino flock in a semi-intensive farming system and that the gestation status should be taken into account when measuring these parameters in future studies.

Estimates of genetic and environmental (co)variances for live weight and fleece traits in yearling South African Mutton Merino sheep

Yearling live weight and fleece trait data were obtained from between 2214 and 2270 yearling SA Mutton Merino progeny of the Elsenburg flock during a 20-year period from 1983 to 2002. Information of (co)variances for these traits in SA Mutton Merinos is exceedingly scarce in the literature. Estimates of (co)variance components and ratios were thus obtained from these data, using an Animal Model. Coefficients of variation, for live weight as well as greasy and clean fleece weight were above 18%. Corresponding values for clean yield and fibre diameter were below 9%. Estimates of heritability were 0.23 for yearling live weight, 0.38 for greasy fleece weight, 0.39 for clean fleece weight, 0.59 for clean yield and 0.67 for fibre diameter. Maternal permanent environmental variance ratios were only significant for live weight, greasy fleece weight and clean fleece weight, amounting to 0.09, 0.06 and 0.06, respectively. Genetic correlations between yearling live weight and wool weight were positive but low (0.14 for greasy fleece weight and 0.13 for clean fleece weight). Those of live weight with clean yield and fibre diameter were zero and 0.22, respectively. The genetic correlation between greasy fleece weight and clean fleece weight was 0.87. The genetic correlations of greasy fleece weight with clean yield and fibre diameter were –0.07 and 0.21, respectively. Corresponding correlations with clean fleece weight were 0.43 and 0.38, respectively. The genetic correlation of clean yield with fibre diameter amounted to 0.33. In most cases, the derived values were in agreement with those derived from Merino data sets.

A comparison between the body composition, carcass characteristics and retail cuts of South African Mutton Merino and Dormer sheepe/pj

The body composition, carcass characteristics and retail cuts of 61 Dormers (21 rams and 40 ewes) and 35 South African Mutton Merinos (SAMM) (17 rams and 18 ewes) were determined. A range of carcass measurements was recorded. Since there was no sex x breed interaction, only main effects of breed and sex were considered. There were no differences in slaughter weight between Dormer and SAMM sheep at 18 months of age. Dormers had a 2.7% point higher dressing percentage and a 6.2% higher carcass weight than the SAMM. The Dormer had a higher fat content (kidney fat, back-fat depth) than the SAMM. The eyemuscle area of the Dormers was 13% larger than that of the SAMM sheep. Rams were heavier than the ewes at slaughter. All the traits measured, indicated advantages in favour of rams. Only the saturated, monounsaturated fatty acids and polyunsaturated fatty acids to saturated fatty acids ratio differed significantly between the Dormer and SAMM sheep. Based on the fatty acid profile, SAMM meat is slightly healthier than that of Dormer sheep. The higher retail cut weights of Dormers suggested that they were superior to the SAMM as far as meat production was concerned.

Production efficiency of South African Mutton Merino lambs and Boer goat kids receiving either a low or a high energy feedlot diet

Individual feed consumption, utilisation, digestion efficiency and growth of 32 Boer goat (BG) kids and 32 South African Mutton Merino (MM) lambs were investigated after weaning. Two pelleted diets (fed to 16 animals per species) with either a low (LE, 9.89 MJ kg −1 DM) or a high (HE, 12.11 MJ kg −1 DM) metabolisable energy level were fed individually, ad lib, for either 28 or 56 days. MM had significantly higher average daily gains (ADG) than BG. Within a diet there was no significant difference in feed conversion efficiency (FCE) between BG and MM and only the MM FCE differed between the LE- and HE-diets. BG fed LE digested DM, CP and energy more efficiently and had a higher energy retention than MM fed LE. Neither species, nor diet affected N retention. The average daily gain of the MM on the LE-diet for 28 days was significantly lower than for those on the HE-diet. However, there was no significant difference between the ADG of BG on the high or low energy diets. These trends were similar in the group of animals that were fed for 56 days. These results indicate that Boer goats may be finished on a diet with a lower ME-value than is usually formulated for sheep, without a reduction in performance. This may render the BG economically viable for feedlot finishing.

Meat quality of Boer goat kids and Mutton Merino lambs 1. Commercial yields and chemical composition

AbstractCarcass measurements, commercial cuts and chemical composition of the meat of 32 Boer goat (BG) kids and 32 South African Mutton Merino (MM) lambs were investigated. Two pelleted diets (offered to 16 animals per species) with either a low (LE, 9·9 MJ/kg dry matter (DM)) or a high (HE, 121 MJ/kg DM) metabolizable energy level were offered, ad libitum, for either 28 or 56 days. Thereafter the animals were slaughtered and the carcasses dissected into South African commercial cuts. The 8-9-10-rib cut of each carcass was dissected and used for chemical analysis. MM had heavier carcasses (LE: 19·87w. 15·28 kg; HE: 2401 v 17·05 kg), and proportionally heavier ribs and buttocks than BG and therefore one can expect higher prices for sheep carcasses than for those of goats. BG had significantly more moisture and protein and lower fat and energy values than MM. DM, fat and energy values increased with an increase in slaughter age in both species. BG had significantly higher concentrations of 11 of the 18 measured essential amino acids in their 8-9-10-rib cuts than the MM. Goat carcasses had higher Ca, K, Mg, Na and P levels than sheep carcasses, regardless of the diet offered. BG had a lower carcass cholesterol content than lamb (66·77 v. 99·28 mg/100 g, respectively). Palmitic (C16: 0), stearic (C18: 0) and oleic (C18: 1n9) acids comprised the greatest proportions of the fatty acids in the 8-9-10-rib cut. On both diets there was a significantly higher saturated to unsaturated (SFA: UFA) fatty acid ratio in lamb than in goat meat (LE: 0·30 v 0·845; HE 1·407 v. 0·892). It can be concluded that chemically the meat from young feedlot goats is not inferior to that of lamb, and since it has a higher protein percentage and lower fat, cholesterol and SFA it can be considered as a healthy food commodity. Since diet had little or no significant influence on the carcass weight distribution or chemical composition of the goats, BGs can be finished on a LE-diet in the feedlot. This may decrease the food cost significantly.

Meat quality of Boer goat kids and Mutton Merino lambs 2. Sensory meat evaluation

AbstractThe meat palatability, water-holding capacity, colour and shear force values of 32 Boer goat (BG) kids and 32 South African Mutton Merino (MM) lambs were investigated. Two pelleted diets (offered to 16 animals per species) with either a low (LE, 9·9 MJ/kg dry matter (DM)) or a high (HE, 12·1 MJ/kg DM) metabolizable energy level were given to the animals for either 28 or 56 days. Thereafter the animals were slaughtered, the meat cooked and presented to a trained sensory panel. Organoleptically, a difference between goat and lamb was noted. Each one had a specific species flavour, which was not influenced by energy level of the diet. BG meat was perceived to be stringier than that of the MM, but there was no significant difference in Warner-Bratzler shear force values. Tenderness declined with age in both species and there was also a tendency for goat meat to be less juicy than lamb. Chevon had a more pronounced after-taste than lamb. No objective difference could be distinguished between the colour of the cooked goat and lamb, but there was a tendency for fresh lamb to have a higher a*-value (redness) than goat. Although diet did not influence drip loss, drip loss increased with an increase in slaughter age. Only after 56 days did the m. semimembranosus of MM have a significantly higher drip loss than that of BG (LE: 4·84 v. 3·43%; HE: 4·72 v. 3·23%). In the m. semimembranosus of both species cooking loss increased with an increase in slaughter age. It can be concluded that goat meat compares favourably with lamb in terms of water-holding capacity, colour and shear force values. If goats are finished in the feedlot, it can be done on a LE diet, since diet does not influences any of the mentioned characteristics. This may render a direct economic advantage for BG feedlot finishing.

Genetic and environmental effects on lambing and neonatal behaviour of Dormer and SA Mutton Merino lambs

Data were accumulated for birth weight, lambing and neonatal behaviour of Dormer and SA Mutton Merino lambs from 1989 to 1998. Numbers of records amounted to 1167–1298 for SA Mutton Merinos and 1036–1118 for Dormers, depending on the trait analysed. Behaviour traits were expressed as time intervals in minutes. Length of parturition was defined as the period between the first definite sign of impending parturition in the ewe to the birth of a specific lamb. In multiples, the birth of the preceding litter mate was regarded as the beginning of parturition for subsequent litter mates. Other observations on lambs included the intervals from birth to standing for >10 s and from standing to apparently suckling. Single lambs were heavier than twins in both breeds, which were heavier than triplets ( P<0.05). Subsequent multiple lambs had shorter parturitions than singles and first-born multiples ( P<0.05). Triplets were slower ( P<0.05) to progress from standing to suckling than singles. Ram lambs were heavier, with longer parturitions than ewes. Lamb birth weight was curvilinearly related to dam age, while length of parturition tended to decrease with an increasing dam age in SA Mutton Merino lambs. Lambs borne by 2-year-old maidens and 7-year-old ewes generally tended to take longer to progress from standing to suckling. Direct heritability estimates ( h 2±S.E.) in SA Mutton Merinos were 0.11±0.05, 0.03±0.04, 0.10±0.05 and 0.08±0.05, respectively, for birth weight, length of parturition, and intervals from birth to standing and standing to suckling, respectively. Corresponding estimates for Dormers were 0.22±0.06, 0.04±0.05, 0.12±0.05 and 0.12±0.06, respectively. The inclusion of the maternal genetic variance ratio ( m 2) resulted in an improvement in the log likelihood ratio for length of parturition in SA Mutton Merino and Dormer lambs, yielding estimates of, respectively, 0.15±0.04 and 0.14±0.04. Maternal permanent environment variance ratios ( c 2) were 0.18±0.03 for birth weight and 0.17±0.04 for the interval from standing to suckling in SA Mutton Merino lambs. A corresponding c 2 estimate of 0.15±0.06 was computed for birth weight in Dormer lambs. On a phenotypic level, length of parturition was positively related to birth weight in both breeds. Corresponding maternal permanent environmental correlations between the traits amounted to 0.44±0.14 in SA Mutton Merinos and 0.47±0.16 in Dormers. Phenotypic correlations of birth weight with neonatal lamb progress were negative in both breeds, but the only significant maternal permanent environmental correlation was an estimate of −0.75±0.23 between birth weight and the interval from birth to standing. Direct genetic correlations between traits rarely exceeded their standard errors. Lambs that succumbed during parturition and prior to weaning generally had higher ( P<0.05) direct and maternal breeding values for length of parturition. Corresponding results were found when derived breeding values for neonatal progress were related to post-parturient deaths, particularly in Dormer lambs. These results are discussed with reference to sheep production.

Water intake of Boer goats and Mutton merinos receiving either a low or high energy feedlot diet

Individual water consumption and intake per unit body mass gain of 16 castrated Boer goat (BG) kids and 16 South African Mutton merino (MM) wether lambs were investigated. Two pelleted diets (fed to eight animals per species) with either a low (8.9 MJ ME kg −1 DM) or a high (10.9 MJ ME kg −1 DM) metabolisable energy level were fed individually, ad libitum for 56 days. The BG had a 49% lower ( P<0.01) water intake per kilogram mass gain than the MM on both the high and low energy diets. Both species had a lower ( P<0.01) intake on the high than on the low energy diet. Furthermore, the BG had a daily water intake of only 171 ml kg −0.75 compared to the 302 ml kg −0.75 of the MM.

Einfluß von Booroola-Merinos auf Fettgehalt und -qualität der Schlachtkörper bei Kreuzung mit Merinofleischschafen

Abstract. Title of the paper: The effect of Booroola on fat content and fat quality of carcasses in crosses with German Mutton Merinos Taking actual consumer demands into consideration possible influences of fecundity genes, like that of the Australian Booroola Merino (FecB), on fat content, fat distribution and fat quality of lamb carcasses are of special interest. Within a project investigating the introgression of the FecB-gene into German Mutton Merino (GMM) in total 144 male lambs with different portions of Booroola (B) were tested between 1995 and 1997. The animals were fed ad lib. a pelleted grain mixture from 20 up to 42 kg body weight. There are no differences in kidney fat percentage, subcutaneous fat thickness, percentage fat of the loin as well as intramuscular fat (IMF) between carcasses of B-crosses (1/8 or 1/16 B) and GMM. Differences in the fat score disappear in lambs of the third backcross generation. The offspring of heterozygous carriers has a higher percentage of intermuscular fat and less IMF. B-crosses show lower melting points in IMF and kidney fat, which corresponds with changes in the fatty acid composition. Also the ratio between linoleic and linolenic acid was higher, especially in the offspring of gene-carriers. In general the differences between GMM and the involved B-crosses are small and unfavourable estimations of the carcass quality by the consumers are unlikely. Obvious there is no pleiotropic effect of the FecB-gene on fat content, distribution and quality. Correlated effects appear only in a few traits and show no evidence in crossbred lambs with even or less than 1/16 B.

A nutritional evaluation of Geotrichum candidum grown on an industrial effluent

Dormer (n = 166) and SA Mutton Merino (n = 147) ewes were observed continuously during lambing in the autumn lambing seasons of 1989-1991. Although SA Mutton Merino ewes had larger (P ••• 0.01) litters at birth than Dormers (2.08 vs. 1.75), higher (P •••0.05) levels of mortality at birth (0.101 vs. 0.031) and from 3 days to weaning (0.180 vs. 0.110) resulted in this difference being eliminated at weaning (1.35 vs. 1.37). SA Mutton Merino ewes generally took longer to give birth (P ••• 0.01; 92 vs. 67 min) and were more likely to be assisted at birth (P ••• 0.01; 0.231 vs. 0.102) than Dormers. Post-mortem results suggested that birth stress was more prevalent (P = 0.053) amongst 61 perinatal deaths in SA Mutton Merino lambs than in 30 Dormers (0.575 vs. 0.333). Mortalities within ca. 1 week of birth amongst assisted lambs (pooled across breeds) were generally higher than in their unassisted contemporaries, significantly (P ••• 0.05) so in singles (0.444 vs. 0.044) and triplets (0.604 vs. 0.156). Length of parturition was found to be repeatable (t = 0.36 ± 0.07). Permanent and temporary separation of ewes from ~ 1 lamb were independent of breed, but were lower (P ••• 0.05) amongst ewes caring for singles (0.011) than in ewes caring for twins (0.197) or triplets (0.323). Permanent separation was caused by interference and desertion in respectively 0.500 and 0.239 of affected ewes, while lambs followed a non-interfering ewe in 0.174 of cases. Separation was attributed to udder malfunction in 0.043 of the ewes. The incidence of permanent separation caused by interference by other ewes was higher (P ••• 0.05) in Dormer ewes than in SA Mutton Merinos (0.654 vs. 0.300). Ewes moving from their birth sites ••• 120 min after birth were more likely (P •••0.01) to be permanently separated from ~ 1 lamb than ewes which remained longer (0.400 vs. 0.134). This observation was mainly caused by ewes classified as deserting their lamb(s). These ewes left their birth sites sooner (P ••• 0.01) than those that were not separated from any lambs (156 vs. 351 min). Separation of ewes from ~ 1 lamb was related to the density of lambed ewes (r = 0.56) increasing by 2.01% (SEa = 0.35) for 1 lambed ewe/ha. Udder malfunction was recorded in 18 ewes, and was accompanied by high levels of lamb mortality (0.643). Selection against rearing failure should be investigated for the improvement of rearing ability and lamb survival in these flocks, before further attempts are made to increase fecundity. Management should facilitate for ewes remaining on their birth sites for a long time after birth, and avoid stocking densities> 11 pregnant ewes/ha at lambing.

Contemporary comparisons between progeny by Finnish Landrace and Romanov rams out of Mutton Merino and Awassi ewes

Results based on contemporary comparisons of F 1 progeny by Finnish Landrace and Romanov rams out of Mutton Merino and Awassi ewes are given. Within the four genotypes thus produced, the F 1 females were mated to F 1 males to produce F 2 progeny. Mutton Merino crosses were carried through the first lambing and the Awassi crosses through two lambings. All animals were housed and lambs reared on ad lib. concentrates and hay. There were no significant differences between sire breeds in the performance of their F 1 progeny except for wool traits. Awassi crossbred females at 1 year old exceeded the Mutton Merino crosses in proportion lambing (74 vs 65%); lambs born per ewe mated (1.15 vs 0.95); birth weight (5.1 kg vs 4.2) and 150-day weight (46 kg vs 43). Lamb mortality up to 150 days was similar at around 24%. For the Awassi crossbreds at the second lambing the F 2 progeny with finn blood were heavier at birth and grew faster to weaning than those with Romanov blood (4.1 kg and 233 g/day vs 3.6 kg and 198 g/day). Romanov rams either introduced or greatly increased the incidence of pigmented and kemp-like fibres in the wool of their progeny; in the cross with Mutton Merinos they also adversely affected breed type, character and handle.

The fertility of prolific breeds (Finnsheep, Romanov Sheep, East Friesian Milksheep) and their crosses with mutton merino

The fertility of prolific breeds (Finnsheep, Romanov Sheep, East Friesian Milksheep) and their crosses with mutton merino