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Energy, crude protein and dry matter digestibility of pastures are essential components of quality that influence the voluntary intake of grazing livestock. To be able to meet the nutrient requirements of animals for maintenance, growth, gestation and lactation, pasture quality, quantity and efficient utilisation need to be well managed. Seasonal changes in pasture quality imply that a strategic and tactical approach to grazing management needs to be adopted in terms of herd structure, stocking rate and the use of persistent pasture species that can fill the seasonal feed gap. Pastures grazed in green, leafy vegetative condition have the highest nutritional quality. Growing and lactating animals should have priority access before dry stock due to their high nutrient requirements. Maintaining pasture mass above 1000kg green DM/ha promotes rapid growth and checks against overgrazing. Animal intake and pasture quality decline when the mass exceeds 3000kg green DM/ha, therefore, managing pastures to maintain between 1500-2500kg green DM/ha would enhance maximum cattle performance. Completely depending on pastures alone may not meet the nutritional requirements of lactating animals, particularly energy. Strategic supplementation with high-energy grains will fix this.

Phospholipid data from the Longissimus dorsi (eye muscle) of 117 weaners across 7 cattle genotypes were analysed. The aim was to investigate sex and breed differences in fatty acid composition of muscle phospholipids in an entirely grass-fed management situation. Results showed that sex was a significant source of variation in the levels of 18: ln-9, total monounsaturated fatty acids (MUFA) and calculated Δ9-desaturase enzyme activity index. Heifers had higher percentages in all cases than steers. All the other individual fatty acids and the summations of their proportions did not differ between the sexes. Significant breed differences were apparent in 18: ln-9, 18:3n-3, MUFA and Δ9-desaturase enzyme index. Wagyu and Belgian Blue crosses had the highest proportion of 18: ln-9 and Hereford the lowest. Jersey crosses and Hereford breeds had the highest 18:3n-3 levels and Belgian Blue the lowest. Δ9-desaturase enzyme index was highest in the Wagyu crosses. There were no other breed differences detected in all the other individual fatty acids and their summations. This study suggests that in weaners, the fatty acid composition of muscle lipids differs between breeds and sexes. The magnitude of the differences is, nevertheless, more reflected in the adipose tissue than in the muscle phospholipids. Also, Wagyu and Belgian Blue genotypes produced muscles with the most monounsaturated fatty acids.

Variations in weight gain, milk yield, milk composition, nutrient intake and digestibility of Red Sokoto goats supplemented with crop-residue based rations during the long-dry period were investigated. Ration A, the conventional concentrate ration, was used as the positive control, Rations B and C were the two crop-residue test diets, while Ration D the unsupplemented treatment, was used as the negative control. Each of the supplementation rations was fed at 1 and 2% of the goats body weight (designated as 1A, 2A, 1B, 2B and 1C, 2C respectively). The supplemented group of goats had significantly higher (P<0.05) dry matter (DM) and crude protein (CP) intakes as well as nutrient digestibilities than the unsupplemented groups. DM digestibility improved with supplementation by a range of 4.1 to 27.9%, while CP digestibility improved by 17.1 to 42.2%, the highest value being in does on Ration A. It was evident that supplementation significantly (P<0.01) influenced weight gains and milk yield of dams. Goats on ration 2C recorded the highest average daily gains of 39.29 g/day while their counterparts fed rations 1B and D lost 28.57 and 92.86 g/day respectively. Ration 1C which comprised mainly of crop residue with much lesser protein levels than the concentrate ration, produced 54 kg of milk over a 90-day lactation period averaging 0.60 kg per day. Goats on Ration D had the shortest lactation length of 41 days and the least total and average daily milk yields of 10.2 and 0.25 kg respectively. Milk from does on ration 2A contained the highest percentages of fat (6%), protein (6.33%), total solids (21.85%) and solids-not-fat (15.85%). Milk from goats on ration D ranked least with respect to all parameters studied. It was concluded that the goats made appreciable gains in the long dry season on crop-residue based diets that compared favourably with the conventional concentrate rations. Ration C fed at 1% level was a good supplementary feed package for increased liveweight gai

All organisms are subject to mutations as a result of normal cellular operations or interactions with the environment, leading to genetic variation (polymorphism). In conjunction with selection and genetic drift, there arises genetic variation within and among individuals and species. For this variation to be useful to geneticists, it must be heritable and discernable whether as a recognisable phenotypic variation or as a genetic mutation distinguishable through molecular techniques. PCR amplification and gel electrophoresis resolution of products using RAPD primer A2 shows polymorphism of up to 5 bands was evident. It also demonstrates that at the molecular level, there are banding differences that can be picked up between crossbred progeny sired by rams with high genetic merit for growth or muscle.Fat depth at the GR and C sites was significantly (P<0.05) influenced by level of nutrition and nutrition level x siretype interaction in that fat depths were greater in crossbred lambs fed at high levels of nutrition than those fed low nutrition levels. Lambs selected for growth and fed high level of nutrition produced carcasses with the least KNIFE GR fat depth of 11.4mm, a significant reduction from 18.1mm in the control group fed low level nutrition.

The effect of dry season supplementation with crop residue based rations on body weight, scrotal circumference and serum testosterone concentrations in Red Sokoto weaner bucks at 5, 6 and 7 months of age was investigated in this study. There were 7 treatment groups which comprised of a positive control ration (conventional concentrate) fed at 1 and 2% of the bucks' body weights (rations 1A and 2A), two crop residue based test rations each fed at 1 and 2% of body weight (1B, 2B, 1C and 2C) and a negative control that was unsupplemented (ration D). All treatment groups had ad libitum access to natural pastures and Digitaria smutsii hay as basal diet. Body weight and scrotal circumference of the bucks significantly increased (P<0.05) with age from 5.9 Kg at 5 months to 10.2 Kg at 7 months of age and 4.40 cm to 6.95 cm, respectively. Bucks on ration D (unsupplemented group) had the lowest body weight and scrotal circumference. Bucks on ration 2A showed a significant increase in basal testosterone concentration from 0.32 ng/mL at 5 months of age to 0.65 ng/mL at 7 months of age. Peak testosterone concentration also increased from 1.0 ng/mL at 5 months to 2.8 ng/mL at 7 months of age. Bucks on test ration 2C had higher body weights (6.75, 8.00 and 10.00 kg at 5, 6 and 7 months of age, respectively) than bucks on the other test ration B (6.20, 7.20 and 8.50 kg, respectively). There were no significant differences between the two test rations with regards to scrotal circumferences of the bucks at all ages. However, at 7 months of age, bucks on test ration 2C had significantly higher peak testosterone concentration (1.80 ng/mL) than their counterparts on test ration 2B (1.30 ng/mL). The secretory patterns of testosterone were episodic and pulsatile in nature. It was concluded that crop-residue supplementation in pre-pubertal Red Sokoto bucks has a significant influence on their body weight, scrotal circumference and testosterone production. Test ration C was a cheap, afforda

Adipose tissues from the 12th and 13th rib interface were sampled at weaning (324 cattle) and slaughter (310 cattle). The animals were progeny from Hereford dams sired by Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu. Fatty acid composition of the triacylglycerol fraction at both stages was measured by gas-liquid chromatography. Estimates of heritability and genetic and phenotypic correlations at weaning and slaughter were computed by restricted maximum likelihood using a sire model in both univariate and multivariate analyses. Results indicated that generally, there were strong, positive genetic correlations between fatty acids at weaning and slaughter (as high as 0.98). Phenotypic correlations were however, low and poor (0.04 to 0.44). Heritability (h2) estimates at weaning were low to moderate, ranging from 0.0 to 0.31. However, at slaughter, h2 estimates were generally higher than at weaning: Stearate, oleate and total monounsaturates had h2 estimates of 0.43, 0.37 and 0.40, respectively. Other carcass traits such as marbling score and melting point of fat had h2 estimates of 0.20 and 0.52, respectively. Significant breed, sex and location differences in fatty acid composition were also observed at weaning and slaughter.

The Wagyu breed of beef cattle is renowned for its ability to deposit high levels of intramuscular fat resulting in highly marbled beef that meets consumer demands in some niche export markets. We evaluated the post-weaning growth performance and carcass characteristics at slaughter of purebred Wagyu steers raised in the feedlot after an initial backgrounding on grass and silage. Our main aim was to study the average daily gains (ADG), body condition scores (BCS) and liveweight (LWT) changes from weaning to slaughter and to estimate homozygosity and inbreeding coefficients through band sharing patterns using random amplified polymorphic DNA (RAPD) markers. LWT, ADG and BCS were monitored monthly from 2005-2006. Genomic DNA was extracted from blood samples, amplified using RAPD primers, fragments resolved by gel electrophoresis and banding patterns elucidated under UV light. A linear increase in liveweight as age increased was observed and the typical fluctuation due to seasonal variations observed under grazing conditions was unnoticeable. Average LWT ranged from an initial 110kg to 660kg, ADG ranged from 0.7–2.0kg/day and BCS reached the maximum of 5 at the end of the experiment. Average LWT at slaughter was 574kg with a hot carcass weight of 329kg and a dressing percentage of 57%. Mean eye muscle area was 94cm2, eye muscle width 8cm and eye muscle length 16cm. Marbling score was 3, subcutaneous fat depth of 17cm and total trimmed fat weight was 34kg. Average saleable meat yield based on the 4 most valuable hind muscles were: Round (11.7kg), Topside (19.3kg), Rump (13.6kg) and Silverside (15.8kg). Average band sharing frequencies ranged from 0.60 to 0.96 with estimated inbreeding coefficients ranging from 0.5% to 7%, respectively. It was concluded that the inbreeding level was low, negligible and not in any way detrimental to meat yield and carcass quality destined for the Japanese market. Finally, RAPD markers were not versatile enough toclearly differentiate betw

All organisms are subject to mutations as a result of normal cellular operations or interactions with the environment, leading to genetic variation (polymorphism). In conjunction with selection and genetic drift, there arises genetic variation within and among individuals and species. For this variation to be useful to geneticists, it must be heritable and discernable whether as a recognisable phenotypic variation or as a genetic mutation distinguishable through molecular techniques. PCR amplification and gel electrophoresis resolution of products using RAPD primer A2 shows polymorphism of up to 5 bands was evident. It also demonstrates that at the molecular level, there are banding differences that can be picked up between crossbred progeny sired by rams with high genetic merit for growth or muscle.Fat depth at the GR and C sites was significantly (P<0.05) influenced by level of nutrition and nutrition level x siretype interaction in that fat depths were greater in crossbred lambs fed at high levels of nutrition than those fed low nutrition levels. Lambs selected for growth and fed high level of nutrition produced carcasses with the least KNIFE GR fat depth of 11.4mm, a significant reduction from 18.1mm in the control group fed low level nutrition.

Interval mapping within 5 families of Japanese Black Cattle (Wagyu) to detect segregating QTL for birth weight and preweaning average daily gain on bovine chromosome 1 was performed by genotyping 132 half-sib progeny using 98 microsatellite DNA markers. A significant QTL for birth weight was detected at 114cM (95% confidence interval of 50-130.5cM) in one sire. Suggestive QTL for preweaning average daily gain were detected at 14cM and 18cM just below the chromosome-wide threshold in 2 sires. It was concluded that evidence of significant QTL in chromosomal regions of bovine chromosome one was compelling for birth weight hence enhancing the prospects of marker-assisted selection in this breed.

The aims of this study were to evaluate the growth performance of Hereford, Angus, Hereford × Angus and Hereford × Saler heifers within the same herd grazing native pastures and to estimate homozygosity and inbreeding coefcients using random amplied polymorphic DNA (RAPD) markers. Post-weaning liveweight (BW), average daily gain (ADG) and body condition score (BCS) on a scale from 0 to 5 were monitored monthly from 2005 to 2006. Genomic DNA was extracted from blood samples, amplified using RAPD primers, fragments resolved by gel electrophoresis and banding patterns elucidated under UV light. Estimation of homozygosity through band sharing patterns was utilised in determining within-breed inbreeding levels. Regardless of breed, LWT, BCS and ADG of heifers followed a typical sigmoid curve pattern characterised by a decline in average BW from 200 kg in May to 188 kg in June, a continuous monthly increase through to March 2006 when it reached a peak (380 kg) before a nal decline to 375 kg in May. The BCS ranged from 1.6 to 3.6 while ADG ranged from -0.4 to 1.5 kg/d. Significant genetic variation was observed between the different breeds in that BCS and BW of purebred Angus heifers were lower than those of purebred Hereford and their crosses with Angus and Saler. Average BW of the Angus breed ranged from 164-349 kg, with BCS ranging from 1.4 to 3.3 compared to the Hereford (186-383 kg, 1.6-3.6), Hereford × Angus (192-383 kg, 1.7-3.6) and Hereford × Saler (192-385 kg, 1.6-3.7), respectively. The ADG of the Angus was not different from those of Hereford and their crosses indicating that the Angus was perhaps better in terms of feed efciency since they probably ate less and gained the same weight as the heavier breeds that must have eaten more commensurate with their maintenance requirements. The strongest residual correlation (r=0.98) was between BW and BCS. Average band sharing frequencies ranged from 0.60 in the crossbreds to 0.96 in the purebreds with estimated inbr

RAPD marker assays are based on polymerase chain reaction amplification of random segments of the DNA with an identical pair of primers 8-10 bp in length consisting of arbitrary nucleotide sequence. Genetic variation and divergence within and between breeds of interest are assessed by the presence or absence of each product which is dictated by the DNA sequence at each locus. The power to detect polymorphisms is very high given that 5-20 bands can be produced using a given primer pair and multiple sets of random primers can be used to scan the entire genome for differential RAPD bands. RAPD has several advantages over other molecular markers because it can be used with uncharacterised genomes without prior knowledge of nucleotide sequence information and can be applied to problems in which only small quantities of DNA are available. It is also efficient and inexpensive.At the same slaughter weight and body condition score, Corriedales had significantly (P<0.01) higher fat score, thicker subcutaneous fat (29.6 vs 23.3 mm) and wider eye muscle (49.8 vs 36.2 mm) than East Friesians. On the other hand, East Friesians had significantly (P<0.01) heavier hot carcass weight (23.8 vs 22.3 kg), larger eye muscle area (42.9 vs 39.5 cm2) and longer eye muscle (67.1 vs 65.6 mm) than Corriedales, while shortloin length (SLL) in the two breeds did not significantly differ (P>0.09).

The detection and mapping of segregating quantitative trait loci (QTL) that influence withers height, hip height, hip width, body length, chest width, chest depth, shoulder width, lumbar width, thurl width, pin bone width, rump length, cannon circumference, chest girth, abdominal width and abdominal girth at weaning was conducted on chromosomal regions of bovine chromosome one. The QTL analysis was performed by genotyping half-sib progeny of five Japanese Black sires using microsatellite DNA markers. Probability coefficients of inheriting allele 1 or 2 from the sire at specific chromosomal locations were computed. The phenotypic data of progeny were regressed on these probability coefficients in a within-common-parent regression analysis using a linear model that included fixed effects of sex, parity and season of birth, as well as age as a covariate. F-statistics were calculated every 1 cM on a linkage map. Permutation tests of 10 000 iterations were conducted to obtain chromosome-wide significance thresholds. A significant QTL for chest width was detected at 91 cM in Family 3. The detection of this QTL boosts the prospects of implementing marker-assisted selection for body conformation traits in Japanese Black beef cattle.

Fatty acid composition, marbling score and melting point data collected between 1994 and 1996 were analysed. The data were from the adipose tissue of 764 Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu crossbred cattle slaughtered after lot-feeding at 500 days of age. The aim was to investigate sire-breed differences and to estimate heritability and genetic and phenotypic correlations. Significant breed differences were found: Jersey crosses had the highest marbling score and Belgian Blue crosses had the lowest. Limousin crosses had the highest melting point and Jersey crosses the lowest. South Devon crosses had the highest proportion of stearate and Jersey crosses the lowest. Desaturation indices in C16 and C18 fatty acids were highest in Jersey crosses and lowest in Limousin and South Devon crosses. In contrast, there were no breed differences in the proportions of palmitate, oleate, total saturated, total mono-unsaturated fatty acids and elongation index. Heritability estimates of individual fatty acids and their summations, melting point and marbling were low to moderately low (0.05 to 0.27). Strong genetic correlations of melting point and desaturation index in C16 fatty acids (-0.93), melting point and stearate (0.62), marbling and stearate (-0.71) and marbling and desaturation index in C18 fatty acids (0.62) were observed. Phenotypic correlation were generally low. The results imply that fatty acids in the adipose tissue of lot-fed cattle have a moderately low heritability, hence genetic progress might be slow.

Longissimus dorsi muscle tissue was biopsied between the 12th and 13th ribs of 96 purebred Jersey, purebred Limousin and Jersey x Limousin crossbred calves at the age of 9 to 10 months. Fatty acids of the phospholipid fraction were extracted and analysed for sex and breed differences. Heterosis, additive and maternal variances were estimated. All calves grazed pasture in a single management group and were biopsied from the same anatomical site. Steer calves had significantly higher proportions of the 14:0, 14:1, 18:2, 20:3 fatty acids and less of the 16-di-methyl-acetal than heifer calves. Significant breed differences were observed: Limousin calves had the highest proportions of 16:0, 24:0 and saturated fatty acids (SFA), whereas Jersey x Limousin calves had the most 18:0 and elongation index. Dominant effects were evident in the proportions of 16:0, 18:0, SFA and elongation index. Additive genetic effects were significant in the proportions of 16:0, 18:0, 18:1n-9, total SFA and desaturation and elongation indices. Combined maternal and additive effects were significant for long chain polyunsaturated fatty acids 18:2, 20:3 and 20:4.

Adipose tissues from the 12th and 13th rib interface were sampled at weaning (324 cattle) and slaughter (310 cattle). The animals were progeny from Hereford dams sired by Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu. Fatty acid composition of the triacylglycerol fraction at both stages was measured by gas-liquid chromatography. Estimates of heritability and genetic and phenotypic correlations at weaning and slaughter were computed by restricted maximum likelihood using a sire model in both univariate and multivariate analyses. Results indicated that generally, there were strong, positive genetic correlations between fatty acids at weaning and slaughter (as high as 0.98). Phenotypic correlations were however, low and poor (0.04 to 0.44). Heritability (h2) estimates at weaning were low to moderate, ranging from 0.0 to 0.31. However, at slaughter, h2 estimates were generally higher than at weaning: Stearate, oleate and total monounsaturates had h2 estimates of 0.43, 0.37 and 0.40, respectively. Other carcass traits such as marbling score and melting point of fat had h2 estimates of 0.20 and 0.52, respectively. Significant breed, sex and location differences in fatty acid composition were also observed at weaning and slaughter.

Jersey and Limousin non-lactating cows were sampled at two different seasons to determine the beta-carotene concentration and fatty acid profiles of subcutaneous adipose tissue. Results demonstrate significant differences between the Jerseys and Limousins in the concentration of beta-carotene and 14:1, 16:0, 18:1(w-7) and 18:3(w-6) fatty acids. Seasonal variations did not affect beta-carotene concentration but had a major effect on most fatty acids and ratios of fatty acid groups. There was no correlation between beta-carotene concentration and individual fatty acids which may indicate that there is no direct effect of beta-carotene on fatty acid metabolism.

All organisms are subject to mutations as a result of normal cellular operations or interactions with the environment, leading to genetic variation (polymorphism). In conjunction with selection and genetic drift, there arises genetic variation within and among individuals and species. For this variation to be useful to geneticists, it must be heritable and discernable whether as a recognisable phenotypic variation or as a genetic mutation distinguishable through molecular techniques. PCR amplification and gel electrophoresis resolution of products using RAPD primer A2 shows polymorphism of up to 5 bands was evident. It also demonstrates that at the molecular level, there are banding differences that can be picked up between crossbred progeny sired by rams with high genetic merit for growth or muscle.Fat depth at the GR and C sites was significantly (P<0.05) influenced by level of nutrition and nutrition level x siretype interaction in that fat depths were greater in crossbred lambs fed at high levels of nutrition than those fed low nutrition levels. Lambs selected for growth and fed high level of nutrition produced carcasses with the least KNIFE GR fat depth of 11.4mm, a significant reduction from 18.1mm in the control group fed low level nutrition.

Sires representing seven diverse breeds were mated to Hereford cows over four years and the progeny slaughtered. Highly marbled Jersey and Wagyu crossbred cattle had softer fat (6% lower melting point) than the other breeds. The Angus crosses marbled like Jersey and Wagyu, but had harder fat similar to the very lean Belgian Blue. Hereford, South Devon and Limousin crosses had harder fat than Angus crosses. The South Devon had similar marbling to the Hereford (moderate), but with much less P8 fat (similar to Limousin). Heritabilities were low (e.g. marbling 18%) to moderate (e.g. carcass weight 36%) for the various carcass traits measured.

The fat content of muscle and the fatty acid profile and melting point of subcutaneous fat was examined in the progeny of three years of crossbreeding Angus, Belgian Blue, Hereford, Jersey, Limousin, South Devon and Wagyu sires with Hereford cows. Significant cohort and sire breed effects were recorded for most traits. Heritability was moderate in most cases. As expected, significant breed differences were noted in the fat content of muscle, but also apparent was the difference in the degree of unsaturation in Jersey and Wagyu progeny. Angus, Hereford, Belgian Blue, South Devon and Limousin animals varied in some fatty acid measures. Jersey and Wagyu had fat with lower melting point (a function of fatty acid composition) and South Devon and Limousin had higher melting point than the remaining breeds.

Estimated Breeding Values (EBVs) of bulls are useful indicators of the genetic transmission ability of an animal of desirable traits to their progeny. Lactation profile differs between different merit cows but for pasture-based production systems, the impact of emerging EBV evaluation methods remains largely unpublished. In this study, Wood’s incomplete gamma model (Y(t) = atbe−ct ) was utilised to compare the effects of the Australian Selection Index (ASI) and Australian Profit Ranking (APR) EBVs on the shape of the lactation profile of first-parity, pasture-based Holstein-Friesian cows. Initial yield and the rate of increase to peak were significantly influenced by EBV choice, although peak yield was not. It was concluded that Wood’s incomplete gamma function adequately modelled the lactation profile of pasture-based cows explaining over 90% of the observed variation irrespective of using ASI or APR sire breeding values.

A first attempt at estimating the heritabilities of total saturated (SFA), monounsaturated (MUFA)and polyunsaturated (PUFA) fatty acids from the triacylglycerol fraction of adipose tissues is presented. The data were from subcutaneous fat biopsies of 324 weaner steers and heifers across 7 genotypes and 26 sires. These animals all went into the feedlot postweaning, but the carcases of 150 at slaughter were sampled for fatty acid analysis. Results showed that weaner SFA, MUFA and PUFA had heritability estimates of 15, 16 and 0% respectively. At slaughter, estimates of heritabilities were 23, 57 and 15% for SFA, MUFA and PUFA respectively. Since monounsaturated fatty acids are highly desirable given their cholesterollowering ability, this study suggests that selective breeding for MUFA has a good prospect of making genetic progress given the high hL of 57%. A larger data set would shed more light on the precision and accuracy of the estimates presented since these are based on a small data set.

Fat colour score (FCS), beta-carotene concentration and their relationship were examined in carcasses of Jersey, Limousin, and Fl heifers and in biopsy samples of Jersey, 3/4 Jersey, and 3/4 Limousin weaners. Results demonstrate significant differences between all breeds in beta-carotene concentration and FCS. High correlations between FCS and beta-carotene concentration were also demonstrated. Sex differences in FCS and beta-carotene concentration were not significant. The shape of the distributions of beta-carotene content in fat varied between the breeds. High outliers were observed for the pure Jersey, 3/4 Jersey, and Fl and not observed in Limousin and 3/4 Limousin. Based on this preliminary data, we confirmed that beta-carotene concentration in fat of cattle has a genetic basis and hypothesise that a major gene(s) may be involved.

The study reported was conducted to investigate whether fast growing heifers eventually become good milkers in a bid to assist dairy farmers in selecting their replacement stock at an early age. The data analysed consisted of 549 body weight records at birth, 3, 6, 9 and 12 months of age of Friesian-Bunaji crossbred heifers, as well as 840 records on their subsequent lactation length, total lactation yield and estimated 305-day yield collected over a 23-year period (1967-1989). Phenotypic correlations between body weights at fixed ages were all positive and highly significant (P<0.0l), ranging from 0.30 to 0.79. Correlations among milk traits were also positive and highly significant, the range being 0.74 to 0.95. Correlations between body weights and milk traits on the other hand, were very low and non-significant, ranging from 0.01 to 0.14. Equations fitted from simple, multiple and polynomial regressions of body weights on total lactation yield gave very low R2 values. It was therefore concluded that body weights at birth, 3, 6 and 12 months of age have little value in the prediction of future milk yield of Friesian-Bunaji heifers.

Genetic and phenotypic parameters for dairy traits were computed using data on Friesian-Bunaji crossbred cows collected over a twenty-three year period (1967-1989) from the dairy herd of the National Animal Production Research Institute Shika, Zaria, Nigeria. Estimated repeatabilities computed from variance components were 0.72 ± 0.06,0.60 ± 0.10,0.73 ± 0.02,0.53 ± 0.24 and 0.56 ± 0.18 for total lactation yield, lactation length, 305-day yield, calving interval and dry period, respectively. Heritability estimates were 0.44 ± 0.07,0.52 ± 0.12,0.30 ± 0.13,0.18 ± 0.02,0.26 ± 0.08 and 0.27 ± 0.10 for total lactation yield, lactation length, 305-day yield, calving interval, dry period and age at first calving,respectively. Genetic and phenotypic correlation coefficients between traits were medium to high, ranging from 0.30 to 0.95. The results of this study showed that the genetic response to selection in Friesian-Bunaji crosses for total lactation yield, 305-day yield and lactation length could be moderately high since the proportion of additive genetic variance was fairly high. Improvement programmes for age at first calving, calving interval and dry period should focus mostly on management, given their low heritability estimates.

Phospholipid data from the Longissimus dorsi (eye muscle) and M. brachii (shoulder muscle) of Jersey and Limousin cattle were used to study the effects of genotype, anatomical site and their interactions on fatty acid composition. Results indicated that phospholipids of the two muscles did not differ in total saturated, monounsaturated and polyunsaturated fatty acids. However, they differed in specific fatty acids 18:0 and 22:5. Genotype was a significant source of variation for the individual fatty acids 18:2 and 18-di-methyl-aldehyde (18-DMA). Significant genotype by anatomical site interactions were observed in the levels of 18-DMA, 18:0, 18:2 and 20:5 fatty acids. It was concluded that the fatty acid composition of phospholipids from biopsy samples of the L. dorsi and M. brachii muscles were similar, but there were significant differences in some individual fatty acids. Furthermore, attention should be paid to genotype by anatomical site interactions that can exist in some individual fatty acids.

This study compared the fatty acid composition of subcutaneous biopsies of 324 weaner progeny by Angus, Belgian Blue, Hereford, South Devon, Wagyu, Jersey and Limousin sires mated to Hereford dams. The aim was to investigate sire genotype and sex differences in triacylglycerol fatty acids in a grass-fed management system. Results indicated that sire genotype and sex were significant sources of variation in individual fatty acids and summations of their proportions, while the effects of sire genotype by sex interaction and sire nested within sire genotype were not significant. Limousin crosses had the highest proportion of 18:0 and total saturated fatty acids, but the lowest proportion of 16: 1 and total monounsaturated fatty acids. Jersey crosses had the highest percentage of 16: 1 while Wagyu crosses had the highest proportions of 18: ln-9 and total monounsaturated fatty acids. Total polyunsaturated fatty acids did not differ between genotypes. Heifers contained higher 16: 1, 18: ln-9 and total monounsaturated fatty acids but lower proportions of 18:O and total saturated fatty acids than steers.

Mathematical functions to describe a series of milk test day records have the advantage of minimizing random variation, while simultaneously summarizing the lactation profile. Five empirical functions and two mechanistic models were used to model herd and individual milk yield profiles of multiparous Holstein-Friesian cows on 113, 290 milk yield records (8438 lactations) collected from 1994-2005. The models tested were the incomplete gamma (IG), a modified gamma (MG), an exponential (EXP), a polynomial regression (PR), a mixed log (ML), the bi-compartmental (BC), and Dijkstra (DJ) functions, the latter two being mechanistic models. Each model was fitted using the non-linear (NLIN) function of SAS. Model accuracy was evaluated based on residual mean square (RMS), the magnitude and distribution of residuals, and the correlation between the observed and predicted values. All the models, except MG, did equally well in portraying the lactation profile. Parameter estimates were significant (P<0.05), with large serial correlations indicating biased predictions, especially during mid-lactation. Correlations of residuals and observed herd average lactations ranged between -0.13 (MG) to 0.19 (IG), while that between observed and predicted was between 0.76 and 0.99 for the same models. Lactation curves of individual cow milk yields were more varied, exhibited the tendency for a second peak which were not accurately modeled. Mechanistic models performed best with herd data, the PR model fitted overall best, while the MG model fitted the profile least accurately in this study.

Energy, crude protein and dry matter digestibility of pastures are essential components of quality that influence the voluntary intake of grazing livestock. To be able to meet the nutrient requirements of animals for maintenance, growth, gestation and lactation, pasture quality, quantity and efficient utilisation need to be well managed. Seasonal changes in pasture quality imply that a strategic and tactical approach to grazing management needs to be adopted in terms of herd structure, stocking rate and the use of persistent pasture species that can fill the seasonal feed gap. Pastures grazed in green, leafy vegetative condition have the highest nutritional quality. Growing and lactating animals should have priority access before dry stock due to their high nutrient requirements. Maintaining pasture mass above 1000kg green DM/ha promotes rapid growth and checks against overgrazing. Animal intake and pasture quality decline when the mass exceeds 3000kg green DM/ha, therefore, managing pastures to maintain between 1500-2500kg green DM/ha would enhance maximum cattle performance. Completely depending on pastures alone may not meet the nutritional requirements of lactating animals, particularly energy. Strategic supplementation with high-energy grains will fix this.

Interval mapping within 5 families of Japanese Black Cattle (Wagyu) to detect segregating QTL for birth weight and preweaning average daily gain on bovine chromosome 1 was performed by genotyping 132 half-sib progeny using 98 microsatellite DNA markers. A significant QTL for birth weight was detected at 114cM (95% confidence interval of 50-130.5cM) in one sire. Suggestive QTL for preweaning average daily gain were detected at 14cM and 18cM just below the chromosome-wide threshold in 2 sires. It was concluded that evidence of significant QTL in chromosomal regions of bovine chromosome one was compelling for birth weight hence enhancing the prospects of marker-assisted selection in this breed.

Milk yield and reproductive efficiency are crucial to profitable dairying. Although, genetic improvement in the last few decades has led to substantial increases in milk yield/cow, fertility and reproductive health have declined (Dematawewa and Berger, 1998). In a pasture-based system, a 365 day calving interval is crucial for optimum profit. Hence the need to increase milk yield by improving persistence of lactation rather than peak lactation which puts increased stress on the cows at the time when they should be rebreeding. Peak milk yield, persistency and lactation length are the key components of the lactation profile. Dairy cows with high peak yields are more prone to metabolic and physiological disorders (Terkeli et al 1999). Although estimated breeding values (EBV) in dairy cows in Australia incorporates indices of economic value, such as survival and milking speed, the impact of the current breeding approach and management on the shape of the lactation profile is not clear. Mathematical functions such as those previously used to describe a series of milk test day records (Wood, 1967, Wilmink, 1987), have the advantage of minimizing random variation while simultaneously summarising the lactation profile into biologically interpretable parameters.

The effect of dry season supplementation with crop residue based rations on body weight, scrotal circumference and serum testosterone concentrations in Red Sokoto weaner bucks at 5, 6 and 7 months of age was investigated in this study. There were 7 treatment groups which comprised of a positive control ration (conventional concentrate) fed at 1 and 2% of the bucks' body weights (rations 1A and 2A), two crop residue based test rations each fed at 1 and 2% of body weight (1B, 2B, 1C and 2C) and a negative control that was unsupplemented (ration D). All treatment groups had ad libitum access to natural pastures and Digitaria smutsii hay as basal diet. Body weight and scrotal circumference of the bucks significantly increased (P<0.05) with age from 5.9 Kg at 5 months to 10.2 Kg at 7 months of age and 4.40 cm to 6.95 cm, respectively. Bucks on ration D (unsupplemented group) had the lowest body weight and scrotal circumference. Bucks on ration 2A showed a significant increase in basal testosterone concentration from 0.32 ng/mL at 5 months of age to 0.65 ng/mL at 7 months of age. Peak testosterone concentration also increased from 1.0 ng/mL at 5 months to 2.8 ng/mL at 7 months of age. Bucks on test ration 2C had higher body weights (6.75, 8.00 and 10.00 kg at 5, 6 and 7 months of age, respectively) than bucks on the other test ration B (6.20, 7.20 and 8.50 kg, respectively). There were no significant differences between the two test rations with regards to scrotal circumferences of the bucks at all ages. However, at 7 months of age, bucks on test ration 2C had significantly higher peak testosterone concentration (1.80 ng/mL) than their counterparts on test ration 2B (1.30 ng/mL). The secretory patterns of testosterone were episodic and pulsatile in nature. It was concluded that crop-residue supplementation in pre-pubertal Red Sokoto bucks has a significant influence on their body weight, scrotal circumference and testosterone production. Test ration C was a cheap, afforda

The parameters investigated in this study with the objective of evaluating growth, lactation and reproductive performances, included birth weight, litter size, 0-90 days gain and average daily gain of kids as well as the milk yield and progesterone profile of Red Sokoto does supplemented with crop-residue based rations during the long-dry period of the subhumid zone in Nigeria. A total of 7 treatments of 4 goats each was utilised. All treatment groups had a basal diet of Digitaria smutsii hay and natural pasture ad libitum. Ration A supplemented with the conventional concentrate was used as the positive control; rations B and C were supplemented with crop residues; and ration D without supplement was used as the negative control. Supplementation with concentrate and crop residues significantly increased (P < 0.05) the birth weight and liveweight gains of kids, but littersize was unaffected. The heaviest kids at birth (1.3-1.4 kg) were from does in treatments 1A, 2A and 2C, while does in treatments 1B, 2B, 1C and D had the lightest kids (1.07-1.18 kg). The highest gains of 53.9 g/day-1 were recorded in treatment 2A and the least (32.4 g/day-1) in treatment 1B. Supplementation also significantly influenced (P < 0.01) the daily milk yield of dams over the 90-day period of the dry season. All the does had similar progesterone profiles from late gestation through parturition to early lactation irrespective of their treatment group. It was concluded that ration C fed at the 2% level is a good and affordable supplementary feed package for increased birth weight and preweaning gains in kids for meat production.

Variations in weight gain, milk yield, milk composition, nutrient intake and digestibility of Red Sokoto goats supplemented with crop-residue based rations during the long-dry period were investigated. Ration A, the conventional concentrate ration, was used as the positive control, Rations B and C were the two crop-residue test diets, while Ration D the unsupplemented treatment, was used as the negative control. Each of the supplementation rations was fed at 1 and 2% of the goats body weight (designated as 1A, 2A, 1B, 2B and 1C, 2C respectively). The supplemented group of goats had significantly higher (P<0.05) dry matter (DM) and crude protein (CP) intakes as well as nutrient digestibilities than the unsupplemented groups. DM digestibility improved with supplementation by a range of 4.1 to 27.9%, while CP digestibility improved by 17.1 to 42.2%, the highest value being in does on Ration A. It was evident that supplementation significantly (P<0.01) influenced weight gains and milk yield of dams. Goats on ration 2C recorded the highest average daily gains of 39.29 g/day while their counterparts fed rations 1B and D lost 28.57 and 92.86 g/day respectively. Ration 1C which comprised mainly of crop residue with much lesser protein levels than the concentrate ration, produced 54 kg of milk over a 90-day lactation period averaging 0.60 kg per day. Goats on Ration D had the shortest lactation length of 41 days and the least total and average daily milk yields of 10.2 and 0.25 kg respectively. Milk from does on ration 2A contained the highest percentages of fat (6%), protein (6.33%), total solids (21.85%) and solids-not-fat (15.85%). Milk from goats on ration D ranked least with respect to all parameters studied. It was concluded that the goats made appreciable gains in the long dry season on crop-residue based diets that compared favourably with the conventional concentrate rations. Ration C fed at 1% level was a good supplementary feed package for increased liveweight gai

The general objective of this study was to come up with an appropriate, affordable and locally available crop residue supplementation package that would enhance reproductive performance in small ruminants. Specifically, 28 Red Sokoto weaner does between 3 and 4 months of age weighing between 2 and 3 kg were used in the first experiment to determine the influence of crop residue supplementation on age and weight at puberty as determined by blood progesterone levels. In the second experiment, another 28 adult does (equal to or greater than 2 years old) of the same breed in the same flock with lactation numbers between 1 and 3 were used to determine the length of postpartum acyclic period. In both experiments, a 3 x 2 factorial experimental design comprising three dietary supplements (A, B, C) at two feeding levels (1% and 2% of body weight) fed in addition to a basal diet of Digitaria smutsii hay and natural pasture ad libitum with an unsupplemented negative control group (D) and four goats per treatment was utilized. In ration A, a conventional concentrate supplement consisting of maize, wheat offal, cottonseed cake and bonemeal was utilized; in rations B and C, the supplement consisted of guinea-corn bran, cowpea husk and groundnut haulms; and maize offal, groundnut shells and groundnut haulms respectively. Unsupplemented (ration D) weaner does reached puberty at a later age and had lighter body weights than all the others. Weaner does on ration 2A (concentrate fed at 2% of body weight) attained puberty at the earliest age and heaviest body weight, although the age at puberty was not significantly different from those on rations 1A (concentrate fed at 1% body weight), 1C and 2C. Blood progesterone profiles before and after puberty ranged from 0.05 to 9.0 ng/ml, respectively, and was highest in does fed rations A and C and least in the unsupplemented does. The mean interval between kidding and initiation of ovarian activity was 54.28 plus or minus 17.61 days and the

Energy, crude protein and dry matter digestibility of pastures are essential components of quality that influence the voluntary intake of grazing livestock. To be able to meet the nutrient requirements of animals for maintenance, growth, gestation and lactation, pasture quality, quantity and efficient utilisation need to be well managed. Seasonal changes in pasture quality imply that a strategic and tactical approach to grazing management needs to be adopted in terms of herd structure, stocking rate and the use of persistent pasture species that can fill the seasonal feed gap. Pastures grazed in green, leafy vegetative condition have the highest nutritional quality. Growing and lactating animals should have priority access before dry stock due to their high nutrient requirements. Maintaining pasture mass above 1000kg green DM/ha promotes rapid growth and checks against overgrazing. Animal intake and pasture quality decline when the mass exceeds 3000kg green DM/ha, therefore, managing pastures to maintain between 1500-2500kg green DM/ha would enhance maximum cattle performance. Completely depending on pastures alone may not meet the nutritional requirements of lactating animals, particularly energy. Strategic supplementation with high-energy grains will fix this.

We evaluated ewe conception and prolicacy in six ocks on three sheep farms with similar commercial management conditions in the Australian State of Tasmania. The aim was to investigate the effects of BW and BCS at mating, age group, and breed on reproductive traits. 1759 Merino, Composite Merino/Coopworth (M/Coop), Composite East Friesian/Romney (EF/Rom), and Composite Coopworth/East Friesian/Texel (Coop/EF/Tex) ewes of maiden (7 mo) and mature (18 to 30 mo) age groups were evaluated. Body weight and BCS of ewes were recorded before rams were introduced to the breeding mob. Ultrasound scanning 90 d after ram removal was carried out. Results demonstrated that ewes that conceived were consistently of greater BW and BCS than barren ewes. The average BW of non-pregnant, single, and multiple-bearing ewes were 41.3, 43.7, and 54.6 kg respectively, while their corresponding BCS were 2.77, 2.80, and 2.85. However, highly signicant (P <0.0001) breed, age group, and ock variations were observed: 7 mo-old maiden ewes had a significantly lower conception rate than 18 mo-old ewes at the same BW at breeding. Within the 18-mo age groups, percentages of non-pregnant ewes were 16.7, 3.0, and 2.4% and percentages of multiple fetus-bearing ewes were 1.4, 53.6, and 74.2% for Merino, Coop/EF/Tex, and M/Coop, respectively. The Coop/EF/Tex ocks were consistently more prolic than other breeds with 74.2, and 77.5% of ewes scanned as multiple fetus-carrying at ages 18 and 30 mo, respectively. Above BW of approximately 55 kg, the probability of multiple conceptions began to increase at a greater rate at the expense of single conceptions. The study shows that nutritional management prior to joining in commercial Tasmanian sheep ocks has the potential to increase reproductive performance in ewes. This is of particular importance when ewes are bred as lambs or from breeds with characteristically low fertility levels

In order to challenge old assumptions and break new grounds in teaching and learning in the Animal Sciences, a paradigm shift from the traditional ‘teacher-focus’ to a modern ‘student-centered’ learning approach is necessary. Establishing a synergy (systematic working together in concert) between ‘research-led’ teaching and ‘inquiry-based’ learning enhances students’ understanding of both science content and scientific practices (Edelson et al., 1999). Understanding the scientific concepts of genetics by nutrition interactions in Australian pasture-based sheep, dairy and beef systems is a major dilemma faced by undergraduate students. This difficulty was reflected in the 2006 Animal Production Systems (KLA220) Unit’s student evaluation of teaching and learning (SETL) at the University of Tasmania (UTAS). To address this problem, we implemented an innovative, inquiry-based learning and research-led teaching approach. The primary objective was to enhance students’ critical thinking and target their learning needs through active participation in field experimental trials and hands-on activities. Data from 104 students enrolled in the KLA220 Unit from 2006-2010 were utilized for this study. In addition to the theoretical concepts taught in class, students were exposed to hands-on genetics-nutrition experimental growth trials with sheep, laboratory experiments on intramuscular fat extraction, fat melting point, sensory evaluation of meat eating qualities, data analysis, livestock industry field visits, scientific journal article critiques and seminar presentations. Student learning experiences were evaluated through SETL surveys. On the basis of 83% response rate and quantitative Unit Evaluation mean scores, results indicated a progressive improvement from 3.90 in 2006 to 4.40 in 2010 that exceeded the average Faculty threshold. Free-text student comments revealed that the research-led teaching approach had actively engaged and given them a rich learning experience. This

To better understand the genetic variability in sheep muscle long-chain omega-3 polyunsaturated fatty acids and relationships with lipid synthesis and fat metabolism-related genes, this study investigated the association between polymorphisms of the fatty acid binding proteins (FABP1, FABP2) and Delta-6 desaturase (FADS2) gene clusters. Thirty-one single nucleotide polymorphisms (SNPs) were genotyped in Longissimus dorsi muscle samples from 362 crossbred prime lambs sired by five genetically divergent rams. Total intramuscular lipid long chain fatty acid levels were analysed using gas chromatography. Mixed model statistical analyses revealed that only FADS2 SNP was significantly associated (P<0.01) with intramuscular levels of eicosapentaenoic (C20:5n-3) and docosahexaenoic (C22:6n-3) acids. The results suggest that this SNP is in linkage disequilibrium with functional lipid synthesis pathway associated with higher delta-six desaturase activity. For the first time, this study provides evidence for an association between genetic variants of FADS2 and omega-3 PUFA in sheep muscle. This SNP could potentially be a novel marker of choice for prime lamb producers to effectively select for enhanced muscle omega-3 fatty acid content in their breeding flock.

Feeds and feeding account for a substantial cost of sheep production, hence the quest for alternative sources of nutrients that can facilitate fast growth in prime lambs without comprising meat eating quality is a continuous research endeavour. This study examined the effect of daily oral drenching of grazing prime lambs with a highly nutritious and edible blue-green microalga commonly referred to as Spirulina (Arthrospira platensis) as a supplement for nine weeks on meat eating quality and consumer acceptability. The prime lambs were weaners from Merino ewes sired by Dorset, White Suffolk, Black Suffolk and Merino rams randomly allocated to 3 levels of Spirulina supplementation treatment groups: Control (0%), low (10%wt/vol) and high (20%wt/vol) comprising 8 lambs per treatment. The lambs were balanced by gender (ewes and wethers), body condition score (average of 3.1±0.4) and body weight (average of 37.6±5.2 kg). Lambs were slaughtered in a commercial abattoir and Longissimus dorsi muscle samples barbequed. A consumer tasting panel subjectively evaluated the sensory meat eating qualities of tenderness, juiciness, aroma, appearance and overall liking. The data were subjected to statistical analyses utilising general linear model procedures in SAS with sire breed, sex, Spirulina level and their second-order interactions fitted as fixed effects and sire as a random variable. The consumer panel detected highly significant (p<0.001) differences in meat tenderness with the high supplementation group being the least tender (6.8±0.2) compared to the low (7.6±0.2) and control (8.0±0.2) groups out of a maximum possible score of 10. These results indicated that Spirulina supplementation at a 10% inclusion level produced leaner, healthier meats with relatively little impact on overall eating quality when compared to meat from animals at either 0% or 20% supplementation levels. This will enable prime lamb producers to make informed decisions regarding the most economically via

Spirulina (Arthrospira platensis) is a highly nutritious and edible microalga, but knowledge about the productive response of sheep to Spirulina supplementation is scanty and its impact on intramuscular fat deposition in lambs largely unknown. We tested the hypothesis that Spirulina lowers intramuscular fat levels and improves meat tenderness at low levels of supplementation without detrimental effects on eating quality. Therefore, the objective of this study was to investigate the influence of varying levels of Spirulina supplementation on Longissimus dorsi intramuscular fat (IMF) content and fat melting point (FMP) in crossbred sheep. Twenty four prime lambs sired by Dorset, White Suffolk, Black Suffolk and Merino rams were weaned at six months of age and subjected to a nine-week feeding trial at 3 levels of Spirulina supplementation: Control group (0%), low (10%wt/vol) and high (20%wt/vol) levels. Each treatment group had a random allocation of 8 lambs balanced by gender (ewes and wethers), body condition score (average of 3.1±0.4) and body weight (average of 37.6±5.2 kg). Lambs in the low and high supplementation groups were drenched daily with Spirulina prior to being released for grazing with the control group. Lambs were slaughtered in a commercial abattoir and Longissimus dorsi muscle samples taken for laboratory determination of IMF and FMP. Intramuscular fat and melting point data were subjected to statistical analyses utilising general linear model procedures in SAS with sire breed, sex, Spirulina level of supplementation and their second-order interactions fitted as fixed effects and sire as a random variable. It was evident that the higher the level of Spirulina supplementation, the lower the fat content in which IMF significantly (p<0.05) dropped from 2.1±0.3% in the control group, to 1.6±0.2% and 1.4±0.1% in the low and high supplementation groups, respectively. FMP values were similar between the control (44.0±0.6˚C) and high (44.2±0.2˚C) supplementa

Robust knowledge of the critical determinants of lactation performance and correlations with fertility traits is essential for elucidating the underpinning relationships between genetic merit for high milk yield and reproduction. Holstein-Friesian, Jersey and Holstein-Friesian x Jersey breeds constitute the vast majority of milking cows in Tasmania’s mainly pasture-based dairy farms in Australia where genetics and seasonal fluctuations in pasture quantity and quality influence lactation performance. We tested the hypothesis that many decades of selection for high milk yield will lead to a gradual but progressive decline in reproductive performance under pasture-based production systems. Therefore, the main objective of our research was to conduct a multi-trait analysis of lactation performance in purebred and crossbred dairy cows and quantify the relationships with fertility traits under grazing conditions. Test-day lactation and reproductive performance data from 2006-2010 in 428 dairy farms in Tasmania with an average herd size of 300 cows were subjected to general linear models and correlation analyses. Lactation performance was found to be a function of breed, physiological status and age of the cow, regional location, season and year of calving. Older, multiparous, Holstein-Friesian cows gave significantly higher milk yields than younger, primiparous calvers with a linear increase in milk yield, protein, fat and calf birth weight as cow parity increased from 1 to 3. Lactation and fertility traits had an antagonistic relationship as high milk yield was associated with increases in calving interval, interval to first breeding and number of days open. It was concluded that for unbiased comparisons of cow mating plans, milking routines between and within pasture-based and seasonally bred dairy herds, adjustments for breed, parity, regional location, season and year of calving will be necessary. Furthermore, a balance must be struck between selecting for high milk y

Ghrelin growth hormone secretagogue receptor 1a (GHSR1a) is involved in many important functions, including growth hormone secretion and food intake (Howard et al. 1996). To the best of our knowledge, there have been no reports to date on nucleotide polymorphisms from the 5’-flanking region to the 3’-UTR nor on the transcriptional analysis of the 5’-UTR of the GHSR1a gene in cattle. In our previous study (Malau-Aduli et al. (2005)), the GHSR1a gene was reported as a potential candidate gene when we detected growth trait QTLs in Japanese Black cattle using microsatellite DNA markers and half-sib regression analysis. Here we describe (1) all possible nucleotide polymorphisms from the 5’-flanking region to the 3’-UTR of the GHSR1a gene, (2) the transcript sequences of the 5’-UTR of the gene, which allows one to determine whether the microsatellite locus has been transcribed, and (3) an association between nucleotide polymorphisms of the gene and growth and carcass traits in Japanese Black cattle (Komatsu et al. (2010)). Finally, we propose a hypothesis that the association is due to differences in RNA secondary structure of the GHSR 1b mRNA.

Spirulina (Arthrospira platensis) is an edible cyanobacterium rich in protein and several essential fatty acids, amino acids, vitamins and minerals. This has raised its profile as a potential supplement in lamb production. Yet, the underpinning effects of Spirulina supplementation on lamb products – wool and meat – interrelations vital to its applicability in the sheep industry is presently largely unknown. Therefore, our experimental objective was to evaluate the correlations between changes in wool quality traits, body conformation and liveweight measurements in lambs supplemented with Spirulina, as affected by sex and supplementation level. Over two consecutive years (2011-12) at the University Farm Cambridge, Tasmania, Australia, a mating ratio of 1 terminal ram to 100 Merino ewes was applied to produce approximately 1600 crossbred progeny. At 12 weeks of age, all progeny were weaned onto ryegrass pasture. At 6 months old, a total of 48 lambs was randomly selected for each feeding trial (24 per year). These were then randomly allocated into Spirulina supplementation treatment levels – CONTROL (0mL), LOW (100mL) or HIGH (200mL) – and balanced by sex – ewes and wethers. Each feeding trial continued for 9-weeks including 3-weeks of adjustment, during which Spirulina was directly supplemented daily to lambs via oral drenching as a water suspension with a 1:10 w/v ration of Spirulina (g) : Water (mL). All lambs received barley grain daily (150g) and had ad libitum access to drinking water and a basal diet of ryegrass pasture throughout the trial. Individual lamb body conformation and liveweight measurements were taken at the start and end of each feeding trial on chest girth (CG), wither height (WH), body length (BL), body condition score (BCS), and liveweight (BWT). Midside wool samples were taken and analysed for clean fleece yield (YIELD), mean fibre diameter (FD), coefficient of fibre diameter variation (CV), fibre diameter standard deviation (SD), comfort factor