- QUESTION: "I am curious about registration. How many of you do not register your animals? How do those of you who do feel about those who do not? Does it hurt the industry?" The above question was posted in a social media group. And the ANSWER is…[drum roll please] it depends. There isn't a "correct" answer.
Selenium Supplementation Increases Wool Growth and Reduces Faecal Egg Counts of Merino Weaners in a Selenium-Deficient AreaThis paper reports on the effects of selenium supplementation on liveweight (LW), greasy fleece weight (GFW), fibre diameter (FD), impact of parasite infection and plasma glutathione peroxidase (GSH-Px) activity in weaned Merino sheep reared in a selenium-deficient area (blood GSH-Px < 40 U/g Hb). At weaning, 208 Merino wethers were assigned to two groups: control (CTRL) and treatment (SEL). The SEL group was injected with 0.5 mL of Deposel, a slow release selenium injection. LW, blood and faecal samples were taken at 6-week intervals over a 24-week period. At the end of the trial the animals were shorn and GFW and FD measurements were taken. The SEL group had significantly higher (P < 0.01) LW compared with the CTRL group at Weeks 6, 12, 18 and 24. There was a significant difference (P < 0.05) in GFW between the SEL and CTRL group, 2.93 and 2.75 kg, respectively. There was no difference in FD between the two groups. A trend (P < 0.06) towards lower faecal egg counts in the SEL group was seen but the difference between the two groups was not significant. As expected, the SEL group had significantly (P < 0.001) higher plasma GSH-Px activity compared with the CTRL group. In conclusion, selenium supplementation in weaned Merino sheep reared in a selenium-deficient area could increase the LW and GFW of the young sheep while perhaps reducing the level of parasitic infection.
Seasonal Variation in Fibre Diameter and Length in Wool of Grazing Merino Sheep with Low or High Staple StrengthThe associations between fibre growth characteristics and wool staple strength were investigated in groups (n = 10) of Merino wethers with either low or high staple strength. Sheep grazed together on pastures based on subterranean clover and annual rye grass for about 13 months. The sheep were weighed and injected intradermally with [35 S]-cysteine at about 14-day intervals. Mid-side patches were harvested and dye bands placed in the wool at about 28-day intervals. Patch clean wool growth, pasture digestible dry matter/ha and pasture crude protein/ha had similar seasonal amplitudes of production (287, 286 and 267% of respective minimum). These were significantly higher than the seasonal amplitude in liveweight (24.5%). The seasonal amplitude in fibre diameter was significantly greater than that for rate of fibre elongation (71.4 and 41.4% respectively). This seasonality in fibre length and diameter resulted in statistically significant seasonal fluctuations in the ratio of fibre length growth to fibre diameter. Fortnightly variability in fibre diameter was not significantly related to variability in fibre length growth rate between sheep for individual time periods. However, for the pooled data over the experimental period a statistically significant relationship (R2 = 0.13, P < 0.01) was improved with the addition of parameters for sampling time and staple strength group. Staple strengths for the low and high staple strength groups were 25.6 and 32.8 N/ktex respectively (P = 0.057). There were no significant differences between the staple strength groups in seasonal change in liveweight, wool production or fibre parameters measured in this study but the low staple strength group had longer fibres. Staple strength was most highly correlated with mid-side fibre diameter coefficient of variation (R2 = 0.50) followed by seasonal amplitude in liveweight.
Do Price Premiums for Wool Characteristics Vary for Different End Products, processing Routes and Fibre Diameter Categories?No Australian wool price hedonic studies have separated auction data into different end product-processing groups (PPR) on the basis of all fibre attributes that affect the suitability of wool sale lots for PPR. This study was conducted to assess: (1) whether including information about PPR groupings is more useful in understanding price than clustering by broad fibre diameter (FD) categories, and (2) if the ‘noise’ of macroeconomic effects on price can be reduced by using a clean price relative to the market indicator (RelPrice) formula or a log RelPrice formula compared with log price or clean price. Hedonic models using data derived from 369 918 Australian auction sale lots in 2010–2011 were estimated for these four dependent price variables. Linear FD models predicted less of price’s variance than quadratic or exponential models. Segmenting wool sale lots into 10 PPR before wool price analyses was found to increase the proportion of price variance explained and thus be worthwhile. The change in price with a change in FD, staple length and staple strength differs significantly between PPR. Calculating RelPrice or log RelPrice appears a better price parameter than clean price or log price. Comparing the RelPrice and clean price models, the mean absolute percentage errors were 6.3% and 16.2%, respectively. The differences in price sensitivity to FD, staple length and staple strength across PPR implies a complex set of price-setting mechanisms for wool as different users place different values on these wool properties. These price-setting mechanisms need to be incorporated in hedonic models for agricultural products that possess this characteristic. The wool price premiums can be used to estimate relative economic values when constructing sheep breeding selection indexes and can help determine the most profitable wool clip preparation strategies.
- The effect of maintenance v, submaintenance diets of pregnant ewes in 1991 and 1992 on establishment of the wool follicle population in their progeny, and its effect on the progeny's wool production (quantity, quality and variation across the body of the animal) to 1.4 years of age was examined. The experimental protocol used cloned animals created by bisecting embryos at day 6 of pregnancy. Each clone was placed in a ewe, which was subsequently fed from about day 50 to 140 of pregnancy at maintenance or submaintenance. Ewes on maintenance nutrition maintained liveweight throughout pregnancy, while submaintenance ewes were 12.1 kg lighter (P < 0.001) 10 days before lambing. In 1991, a total of 74 lambs were born, including 17 sets of surviving clones. In 1992, 102 lambs were born, including 18 sets of surviving clones. Only data for the 35 sets of genetically identical 'twin' progeny and their dams are reported. Birth weights of lambs born to ewes fed at the submaintenance rate were 0.5 kg lighter (P < 0.01) than their 'twins' born to ewes fed at maintenance. Midside secondary:primary (Sf: Pf) ratios for mature wool follicles were less (P < 0.01) at birth, lamb and hogget shearing (1.4, 1.5 and 2.1 units respectively) for the progeny born to ewes fed at submaintenance. Progeny from ewes on the submaintenance treatment produced less clean wool, 0.1 kg to 0.4 years of age (P < 0.01) and 0.14 kg between 0.4 and 1.4 years of age (P = 0.10), than their maintenance counterparts. Hogget wool was 0.1 pm broader (P < 0.05), with a 0.5% units lower coefficient of variation of fibre diameter (P < 0.01), and a position of break closer to the staple tip (P < 0.001) for progeny of submaintenance ewes than their maintenance counterparts. There were no significant differences in yield, staple length, staple strength and percentage of fibres greater than 30 pm in diameter. Differences in mean fibre diameter arose between 1 and 1.4 years of age, coinciding with the period that the animals were grazing high quality pasture. Effects of maternal undernutrition on mean fibre diameter and Sf: Pf follicle ratios of progeny were most pronounced on the hind leg (P < 0.01), and not significant on the front leg. However, variations in other wool quality traits across the body of the hoggets, expressed as a percentage of the midside value, were not significantly affected by maternal undernutrition. Clearly when evaluating management strategies for the pregnant ewe, the effect on lifetime production and quality of wool of their progeny needs to be considered. Merino hoggets that produce an extra 0.14 kg clean wool that is 0.1 pm finer will compensate for some extra management and feeding of their dams during pregnancy to prevent weight loss. If these effects continue throughout the life of the animal, then it will increase the cost effectiveness of feeding to maintain maternal weight over pregnancy.