D. R. Scobie

Dag score is negatively correlated with breech bareness score of sheep

At weaning in two consecutive years, traditional Romney and composite lambs (crosses with East Friesian and Texel; n = 3254) were observed on a conventional farm and Perendale and composite lambs (crosses with Texel, Wiltshire and small numbers of Finnish Landrace; n = 2095) were observed on an organic farm. Both were ram breeding farms recording pedigree and performance, and the composite breeds were developed from, and run with, the original flock on each farm. Breech bareness was scored on the lambs between 80 and 120 days of age on a scale from 1, with wool right to the edge of the anus, to 5, where a large bare area surrounded the perineum. Dag score was recorded on a 0–5 scale where an increasing score indicated more dags. Within farms, mean dag score was more pronounced in traditional Romney (1.2) than in composite lambs (0.4), and Perendales were more daggy (1.3) than composite lambs (0.7) across both years (P < 0.001). Dag score was phenotypically correlated with breech bareness score on the Romney farm (−0.18 ± 0.02) and Perendale farm (−0.27 ± 0.03). Combining data from both flocks, heritabilities of breech bareness score (0.55 ± 0.04) and dag score (0.41 ± 0.05) were high, and a strong genetic correlation was observed between the two traits (−0.59 ± 0.07). Mean dag score of ram lambs was greater than ewe lambs (0.8 v. 0.7, P < 0.001) and lambs reared as twins were more daggy than singles (0.8 v. 0.7, P = 0.008). Composite sheep have been adopted throughout New Zealand for the advantages they deliver in lamb production, but through breech bareness they also provide an opportunity to limit dag production and thereby improve both welfare and profitability. Genetically increased breech bareness and decreased dagginess could be used in Australia as alternatives to mulesing.

The proteomics of wool fibre morphogenesis.

Gel and gel-free proteomic techniques have been used for the first time to directly study the proteins present in whole wool follicles and dissected portions of follicles that correlated with morphological changes in the developing fibre as determined by transmission electron microscopy. Individual wool follicles were dissected into four portions designated as the bulb, elongation, keratogenous and keratinisation portions. Gel-free proteomic analysis of dissected portions from 30 follicles showed that the first keratins to appear were K31, K35 and K85, in the bulb portion. The first epithelial KAP, trichohyalin, was detected in the bulb portion and the first cortical KAP, KAP11.1 was found in the elongation portion. Other major trichocyte keratins and cortical KAPs began to appear further up the follicle in the keratogenous and keratinisation zones. These results were consistent with what has been observed from gene expression studies and correlated well with the morphological changes observed in the follicle. Other proteins detected by this approach included the keratin anchor protein desmoplakin, as well as vimentin and epithelial keratins, histones, ribosomal proteins and collagens. Two-dimensional electrophoretic (2DE) analysis of dissected portions of 50 follicles revealed substantial changes in the position, number and intensity of the spots of the trichocyte keratins as they progressed through the follicle zones, suggesting that they are subject to modification as a result of the keratinisation process. Also present in the 2DE maps were a number of epithelial keratins, presumably from the inner and outer root sheaths, and the dermal components.

Breech bareness reduces flystrike in New Zealand crossbred sheep

Twoexperimentsontheeffectofbreechbarenesson flystrikearereportedhere.Siresfromcommercialsources (n=2)andfromamixedbreed flockselectedforbreechbareness(n=5)werematedtoewesfromthesame flockandRomney ewes. Lambs (n = 211) were run as one mob from docking to weaning. Within 2 days before weaning, flystrike affected severallambs.Atweaningthelambswereinspectedforbreechbarenessscoreanddagscore.Flystrucklambswererecorded, treated and removed at weaning. The remaining lambs (n = 185) were regularly inspected and treated for flystrike, and the incidence of flystrike was recorded again 1 month later. There were no significant differences between sire groups, but the progeny of Romney dams were more likely to be flystruck (18.7 vs 3.4% and 24 vs 3.7%) on both occasions (P < 0.05). Flystrikeincreasedwithincreasingdagscore(P <0.001)butdagscoredecreasedwithincreasingbreechbareness(P <0.001). Theeweprogeny(n=800)of17Romneysireswererunasone flockfollowingweaningonacommercialfarmintheNorth Island of New Zealand. The lambs were inspected for breech bareness, dag score and the incidence of flystrike following a briefperiodof flychallenge.Asbreechbarenessscoreincreased,dagscoredeclined(P <0.001)withasignificanteffectofsire on dag score (P < 0.001). Breech bareness had a significant influence on the proportion of lambs with flystrike (P = 0.028), most likely through dag score which explained a greater proportion of variation in flystrike in multiple linear regression (P < 0.001). Selection against dags in New Zealand crossbred sheep could lower flystrike risk, but selection for increasing breech bareness will reduce both dagginess and flystrike risk.

Skin wrinkles of the sire adversely affect Merino and halfbred pelt characteristics and other production traits

The wrinkles on the skin of Merino sheep and related breeds are retained during leather processing, and the skins are known as ‘ribby pelts’ in the leather trade. Merino sires with either no skin wrinkles (smooth, n = 7) or excessive wrinkles (ribby, n = 7) were allocated at random to mating groups of 22 Merino ewes mixed with 22 Romney ewes. The progeny of ribby sires were more ribby at docking (P<0.001), at shearing (P<0.001), in the fellmongery (P = 0.001) and as pickled pelts (P<0.001). Merino progeny were more ribby than Merino × Romney (halfbred) progeny at all stages. When professionally graded as pickled pelts, smooth-sired progeny produced more pelts without ribs in both Merino (5% v. 0%) and halfbreds (69% v. 38%) than ribby-sired progeny. Wool samples collected at 7.5 months of age were not significantly different between sire groups in mean fibre diameter (P = 0.27) or staple length (P = 0.60) but they were different in standard deviation of fibre diameter (P = 0.003). Liveweight was consistently greater in the progeny of smooth sires, although this difference did not reach significance until the progeny attained a mean liveweight of 28 kg for Merinos and 32 kg for halfbreds (P = 0.016). Breed differences were observed in other traits and these are discussed. Interestingly, there were few significant sire type breed interactions, the exceptions being yield of clean wool (P<0.001), standard deviation of fibre diameter (P = 0.003) and an additional pelt trait referred to as pinhole score (P = 0.003). In summary, choosing sires without skin wrinkles can improve pelt quality, wool quality and liveweight of Merino and halfbred progeny.

Selection for yearling fleece weight and its effect on fleece shedding in New Zealand Wiltshire sheep

A flock of New Zealand Wiltshire sheep was divided into two lines and selected for increased greasy fleece weight or decreased greasy fleece weight as yearlings. Wiltshires shed their fleece annually, and although these yearlings may have expressed shedding as lambs in the preceding summer, they were shorn in autumn at 5 months and again in spring at 12 months of age to determine fleece weight before the subsequent shedding. A rapid separation in fleece weight was observed within 8 years, with ewe (0.89 kg) and ram yearlings (0.92 kg) selected for increased fleece weight producing significantly more wool (P < 0.001) than ewe (0.43 kg) or ram yearlings (0.39 kg) from the line selected for decreased fleece weight. There was no significant difference between sexes, and the sex × line interaction was not significant. Clearly this was very low wool production, but fleece weight was heritable (h2 = 0.57 ± 0.04). Shedding was scored from 0 (not shed) to 5 (completely shed) for all animals (n = 2505 records) and was found to be heritable in December (h2 = 0.39 ± 0.04) and again in January (h2 = 0.52 ± 0.05), but less so in September at shearing (h2 = 0.24 ± 0.03). Fleece weight in spring was negatively correlated with shedding score in January, both phenotypically (–0.52 ± 0.02) and genetically (–0.81 ± 0.04). Selecting yearlings for low fleece weight developed a shedding sheep with negligible fleece, which may not require shearing. Selecting for shedding of lambs in January would likely achieve a similar outcome.

Wool staple tenacity in New Zealand Romney sheep: heritability estimates, correlated traits, and direct response to selection

A flock of New Zealand Romney sheep was established and selected as yearlings on the basis of fleece staple tenacity. The foundation flock was screened from contributing source flocks, with outliers of high or low staple tenacity as yearlings relative to the source flock mean contributing to a ‘high’ line and a ‘low’ line, respectively. A randomly selected control line was established because staple tenacity was known to be affected by yearly changes in feed supply. Staple tenacity of yearling fleeces was found to be heritable (0.41 ± 0.03). After 10 years of within-line selection, the line selected for increased staple tenacity had staples 53% stronger (33.9 N/mm2) than the control (22.1 N/mm2), while staples were 38% weaker in the line selected for decreased staple tenacity (13.8 N/mm2). Staple tenacity was genetically (0.67 ± 0.04) and phenotypically (0.44 ± 0.02) correlated with fibre diameter, and also with staple length (0.38 ± 0.07 and 0.32 ± 0.02, respectively). Longer, thicker fibres likely contributed to positive genetic (0.31 ± 0.07) and phenotypic (0.29 ± 0.02) correlations between staple tenacity and clean fleece weight. The indirect aim of selection was to improve fibre length after carding. Pooled wool samples were prepared from selection line groups of yearlings within sex each year, and a relationship between fibre length after carding measured on these samples and mean staple tenacity of the groups was observed (R2 = 0.514, P < 0.001). Within the tenth (last) year of selection, the high staple tenacity line produced the longest carded fibres (Hauteur: 103 mm) and the decreased staple tenacity line produced the shortest (87 mm), with the control line intermediate (96 mm).

Feeding diets with fodder beet decreased methane emissions from dry and lactating dairy cows in grazing systems

Fodder beet (Beta vulgaris L.) has a very high readily fermentable carbohydrate concentration, which could affect rumen fermentation and reduce enteric methane (CH4) emissions. The objective of the current study was to estimate CH4 emissions from dry dairy cows grazing either fodder beet supplemented with perennial ryegrass (Lolium perenne L.)-dominated pasture silage (6 kg DM/cow/day; FB+Sil) or forage kale (Brassica oleracea L.) supplemented with barley (Hordeum vulgare L.) straw (3 kg DM/cow/day; kale+Str; dry cows, Experiment 1), and from dairy cows in early lactation grazing perennial ryegrass-dominated pasture alone (pasture) or supplemented with fodder beet bulbs (3 kg DM/cow/day; past+FB; lactating cows; Experiment 2). Methane measurements were performed using GreenFeed units (C-Lock Inc., Rapid City, SD, USA) for 40 days in August–September 2015 (Experiment 1) and for 22 days in November–December 2015 (Experiment 2), from 45 and 31 Holstein–Friesian × Jersey dairy cows in Experiments 1 and 2, respectively. Dry cows grazing FB+Sil in Experiment 1 produced 18% less CH4 (g/day) and had 28% lower CH4 yield (g/kg DM intake; P < 0.001) than did cows grazing kale+Str. Lactating cows grazing past+FB in Experiment 2 produced 18% less CH4 and had 16% lower CH4 intensity (g/kg fat and protein-corrected milk production; P < 0.01) than did cows grazing pasture alone, while milk production and composition were similar for the two groups. In conclusion, feeding fodder beet at ~50% and 20% of the diet of dry and lactating dairy cows in pastoral systems can mitigate CH4 emissions.

Like Follicle, like Fibre? Diameter and not Follicle Type Correlates with Fibre Ultrastructure

The hair follicles of most mammals are of two types, primary and secondary. Primary follicles develop earlier and have a prominent arrectorpili muscle. Secondary follicles have less prominent muscles and are often clumped, sharing a common opening from which fibres emerge. It is not entirely clear what types of follicles occur in human scalps. Partly this is because human hairs have a uniform appearance, unlike many mammals in which robust primary hairs differ markedly from narrow secondary fibres. Some sheep breeds are an exception because like humans, wool fibres have a similar macro-scale appearance irrespective of follicle type. How deep does this similarity go Using electron microscopy, we examined wool primary fibres from different breeds and contrasted them to secondary fibres. For fibres of similar diameter, there was no significant difference in the ultrastructure or proportion and distribution of cortex cell types in primary and secondary fibres. We conclude that fibre diameter is the most important fibre parameter with respect to structural differences between fibres, not whether the fibres originate from primary or secondary follicles.

Methane and carbon dioxide emissions from lactating dairy cows grazing mature ryegrass/white clover or a diverse pasture comprising ryegrass, legumes and herbs

There is a growing interest in forage mixtures (Diverse pasture; e.g. containing grasses, legumes and herbs), especially those with a greater tolerance of dry conditions and a decreased nitrogen (N) content (reducing N losses), compared with ryegrass (Lolium perenne L and Lolium multiflorum L)/white clover (Trifolium repens L) pastures (RyeWC), which dominate New Zealand pastoral systems for dairy production. However, the effect of alternative forages on enteric methane (CH4) emissions is not known. The objective of the present trial was to compare CH4 emissions and milk production from dairy cows grazing either mature RyeWC or mature Diverse pasture (both approximately with pasture mass of 5600 kg DM/ha). The Diverse mixture comprised ryegrass, white clover, lucerne (Medicago sativa L), chicory (Cichorium intybus L) and plantain (Plantago lanceolata L). Milk production, measured from cows commencing at ~162 days of lactation, was less when cows grazed RyeWC than Diverse pastures (15.4 vs 16.7 kg/day; P < 0.001), whereas CH4 production (g/day) was similar for the respective treatments (411 g/day; P = 0.16). Milk composition was not affected by diet and CH4 intensity was similar for both diets (22 g/kg fat- and protein-corrected milk; P = 0.31). Methane yield [g/kg predicted dry matter intake (DMI)] averaged 22.6 and 24.9 for cows grazing RyeWC and Diverse pastures, respectively (P = 0.006). In conclusion, although the CH4 yield was greater when Diverse pasture was grazed, relative to RyeWC, there were no differences in emissions intensity or total CH4 emissions.

The proteomics of wool follicles

Messenger RNA hybridisation labelling of hair follicles has revealed that in both sheep and humans there is a sequential pattern to expression of the major keratin and keratin associated proteins (Langbein and Schweizer, 2005; Yu et al., 2009). How expression sequence and post-translational changes relate to fibre development is largely unknown. Thus, this study was initiated to determine if proteomics could provide an insight into protein changes during the various stages of protein synthesis and keratinisation in the maturing wool fibre.