Influence of lupins and canola supplement on short loin fatty acid profiles within genetically divergent first cross merino lambs

Australian consumers are becoming increasingly aware of the health benefits of long-chain omega-3 polyunsaturated fatty acids [LC-PUFA] - eicosapentanoic acid (EPA), 20:5(n-3) and docosahexanoic acid (DHA), 22:6(n-3). The most common dietary source of long-chain omega-3 is through consumption of seafood and fish oil supplements. Common Australian commercial crops of canola and lupin both offer good sources of LC-PUFA precursors,including -linolenic acid [ALA, 18:3(n-3)] and their potential as animal feeds to manipulate LC-PUFA concentrations within animal meat is of great interest to the livestock and human health sectors. This study investigated the LC-PUFA profiles of 38 first cross Merino weaner lambs sired by five genetically divergent rams supplemented with canola meal or cracked lupins at 1% or 2% of body weight feeding levels for 60 days. Results demonstrated that all animals had ‘source’ content of omega-3 (EPA+DHA) in muscle samples taken from the short loin (loin chop) equal to or greater than 30mg per 100g serve. 18 animals were in excess of ‘good source’ content of 60mg per 100g serve with a whole flock mean of 67mg/100g EPA+DHA. When docosapentaenoic acid (DPA) is added to EPA+DHA, only two animals do not reach the ‘good source’ content of long-chain omega-3. Supplement type significantly (P<0.05) affected the level of ALA, with canola meal-supplemented sheep producing 91mg/100g compared to 66mg/100g in lupin-fed sheep. Total saturated fatty acid levels also showed a significant (P<0.05) interaction with sex and supplement indicating that males fed lupins had the lowest levels of SFA 3860mg/100g compared to males fed canola which had 5180mg/100g SFA. Overall the mean long-chain omega-3 content (mg) per 100g for each breed was: East Friesian 75 mg/100g, Dorset 73 mg/100g, Coopworth 68 mg/100g, Texel 59 mg/100g and White Suffolk 58 mg/100g. In conclusion feed supplementation markedly enhanced long-chain omega-3 content of Australian lamb. Level of supplementation, breed and type of supplement had no significant relationship with short loin content of long-chain omega-3 FA. However, when supplementing wethers and ewes with canola meal or lupins, attention should be paid to the significant interactions that exist between sexes and supplement type

Prediction of wool fibre diameter from protein and metabolisable energy digestibility coefficients in crossbred sheep.

Our objective in this study was to investigate the interactions between sire breed and supplement on digestibility and to ascertain its accuracy in predicting wool fibre diameter. Forty first-cross Merino weaner sheep sired by Texel, Coopworth, White Suffolk, East-Friesian and Dorset sires with initial BW range of 22.9 and 31.3 kg (average of 26.8 ± 3.2 kg) were randomly assigned to four treatment groups in a 5 × 2 × 2 × 2 factorial experimental design representing 5 sire breeds, 2 supplementary feeds (canola and lupins), 2 feeding levels (1 and 2% of bodyweight) and 2 sexes (ewes and wethers). The feeding trial lasted for six weeks with an initial 3-week adjustment period and the last 7 days for faecal collection. Factorial ANOVA with orthogonal contrasts in SAS was used for statistical analysis to test for the interactions between sire breed and supplement on digestibility and wool fibre diameter. Our results demonstrated that sire breed × level of feeding interactions significantly influenced digestibility (P<0.01) whereby Coopworth-sired sheep supplemented at 1% of their body weight recorded the highest ME and N digestibility of 54% and 67% compared to 42% and 62% respectively, in their counterparts fed at 2% of body weight. There was a highly significant (P<0.01) effect of type of supplement x level of feeding interaction on wool fibre diameter at the end of the trial because sheep fed canola supplements at 1% of body weight had finer wool (22.1 microns) than their 2%-fed counterparts (25.4 microns). Regression of wool fibre diameter on digestibility revealed very poor prediction accuracy (R2 = 0.0087-0.169). We concluded that sire breed variation in digestibility is unlikely to be a useful predictor of genetic merit for wool fibre diameter in first cross sheep under the same management

Influence of lupins and canola supplements on plasma amino acids, wool fibre diameter and liveweight in genetically divergent first cross Merino lambs

This study hypothesised that there is a positive correlation between plasma amino acids and wool quality parameters of 40 first cross Merino weaner lambs sired by five genetically divergent rams supplemented with canola meal and cracked lupins at 1% or 2% of body weight feeding level for 60 days. Results demonstrated that supplement type significantly (P<0.001) influenced liveweight as canola-fed lambs were heavier (40kg) than their lupin-fed counterparts (37kg), but wool yield, daily wool growth, fibre diameter, and body condition score were unaffected by either supplement or level of supplementation. Supplement type significantly (P0.05), but the interaction between sire breed and supplement type had a significant effect on body condition score of the lambs (P<0.05). Significant interactions between type and level of supplementation (P<0.05) led to a decrease in wool fibre diameter. Lamb gender was a significant source of variation for only plasma arginine (P<0.05). In conclusion, level of supplementation had no significant effect on wool and growth parameters, thus enabling farmers to decrease the cost of feeding by supplementing at only 1% instead of 2% of body weight. For fat lamb production, supplementing with canola is advisable for higher bodyweight gain, whereas for wool production, either canola or lupins (whichever is cheaper) can be used to minimise feed costs. Crossbred sheep producers supplementing lambs with canola will increase plasma histidine with subsequent increase in liveweight and body condition, but at the expense of finer wool because of its positive correlation with fibre diameter. However, wool growth is expected with an increase in the level of plasma lysine

Nutrition-genetics interaction in nutrient utilisation of canola and lupins by Australian sheep: Prediction of wool fibre diameter

High digestibility and nutrient retention of feed on offer are important indices of protein and energy available for wool fibre synthesis or muscle accretion in sheep. The Australian national flock is predominantly based on Merino crossbreds (Fogarty et al. 2005a) where the prime lamb industry exploits crossbreeding in which 40% of the annual slaughter of about 18 million lambs is first-cross progeny from terminal sire rams mated to Merino ewes (Fogarty et al., 2005b). Utilisation of predictive models based on digestibility of protein and energy in sheep would be useful in estimating valuable quality traits such as fibre diameter since wool is a bonus in the prime lamb production sector whose primary product is meat. Our objective in this study was to investigate the interactions between sire breed and supplement on digestibility and to ascertain its accuracy in predicting wool fibre diameter. Forty first-cross Merino weaner sheep sired by Texel, Coopworth, White Suffolk, East-Friesian and Dorset sires with initial BW range of 22.9 and 31.3 kg (average of 26.8 ± 3.2 kg) were randomly assigned to four treatment groups in a 5 × 2 × 2 x 2 factorial experimental design representing 5 sire breeds, 2 supplementary feeds (canola and lupins), 2 feeding levels (1 and 2% of bodyweight) and 2 sexes (ewes and wethers). The feeding trial lasted for six weeks with an initial 3-week adjustment period and the last 7 days for faecal collection. Factorial ANOVA with orthogonal contrasts in SAS was used for statistical analysis to test for the interactions between sire breed and supplement on digestibility and wool fibre diameter. We also utilised both linear and non-linear regressions in modelling the predictive accuracy of fibre diameter from digestibility coefficients. Our results demonstrated that sire breed x level of feeding interactions significantly influenced digestibility (P<0.01) whereby Coopworth-sired sheep supplemented at 1% of their body weight recorded the highest metabolisable energy (ME) and protein (N) digestibility of 54% and 67% compared to 42% and 62% respectively, in their counterparts fed at 2% of body weight. There was a highly significant (P<0.01) effect of type of supplement x level of feeding interaction on wool fibre diameter at the end of the trial because sheep fed canola supplements at 1% of body weight had finer wool (22.1 microns) than their 2%-fed counterparts (25.4 microns). Regression of wool fibre diameter on digestibility revealed very poor prediction accuracy (R2 = 0.0087-0.169). We concluded that sire breed variation in digestibility is unlikely to be a useful predictor of genetic merit for wool fibre diameter in first cross sheep under the same management

Genetic association of delta-six fatty acid desaturase single nucleotide polymorphic molecular marker and muscle long chain omega-3 fatty acids in Australian lamb

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

Rare missense variants in Tropomyosin-4 (TPM4) are associated with platelet dysfunction, cytoskeletal defects, and excessive bleeding

Background: A significant challenge is faced for the genetic diagnosis of inherited platelet disorders in which candidate genetic variants can be found in more than 100 bleeding, thrombotic, and platelet disorder genes, especially within families in which there are both normal and low platelet counts. Genetic variants of unknown clinical significance (VUS) are found in a significant proportion of such patients in which functional studies are required to prove pathogenicity. Objective: To identify the genetic cause in patients with a suspected platelet disorder and subsequently perform a detailed functional analysis of the candidate genetic variants found. Methods: Genetic and functional studies were undertaken in three patients in two unrelated families with a suspected platelet disorder and excessive bleeding. A targeted gene panel of previously known bleeding and platelet genes was used to identify plausible genetic variants. Deep platelet phenotyping was performed using platelet spreading analysis, transmission electron microscopy, immunofluorescence, and platelet function testing using lumiaggregometry and flow cytometry. Results: We report rare conserved missense variants (p.R182C and p.A183V) in TPM4 encoding tromomyosin-4 in 3 patients. Deep platelet phenotyping studies revealed similar platelet function defects across the 3 patients including reduced platelet secretion, and aggregation and spreading defects suggesting that TPM4 missense variants impact platelet function and show a disordered pattern of tropomyosin staining. Conclusions: Genetic and functional TPM4 defects are reported making TPM4 a diagnostic grade tier 1 gene and highlights the importance of including TPM4 in diagnostic genetic screening for patients with significant bleeding and undiagnosed platelet disorders, particularly for those with a normal platelet count