@conference {41524, title = {Flystrike in lambs selected for resistance or susceptibility to ryegrass staggers, when challenged with high or low endophyte pastures}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {64}, year = {2004}, month = {Jan}, pages = {297-299}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Research has shown that incidence of flystrike is reduced in sheep grazing low endophyte ryegrass. This experiment was designed to test the hypothesis that where lambs are bred specifically for resistance to ryegrass staggers (RGS), their susceptibility to flystrike on the body should be correspondingly low, even when challenged with high levels of endophyte. Ewe and ram lambs were sourced from two lines, one selected for resistance (n = 85) and the other for susceptibility (n = 143) to ryegrass staggers. A further group of lambs (n = 63) produced by intercrossing the two lines was included. The lambs were run in 2 mobs, on high and low endophyte pasture, and monitored daily for signs of flystrike on the body. During the course of the experiment, susceptible (n = 34) and resistant (n = 1) lambs suffering from clinical ryegrass staggers had to be removed from the high endophyte pasture. These were excluded from the analysis. Ram lambs made up the majority of animals removed. Only ram lambs were flystruck on the body, particularly around the scrotal area. Significantly more resistant ram lambs (7 of 49) were flystruck than susceptible (3 of 85) or intercross ram lambs (2 of 27), regardless of pasture endophyte level (P < 0.1). More lambs (P < 0.1) were flystruck grazing ryegrass with high endophyte (n = 9) than low endophyte (n = 3). The only lambs flystruck while grazing non-endophyte pasture were RGS resistant rams. In contrast to the hypothesis, this experiment indicates that selection of animals for resistance to RGS may exacerbate their susceptibility to flystrike. The evidence presented here supports the literature that sheep grazing high endophyte pasture are more susceptible to flystrike. The question for farmers is whether their selection priority should be for pasture with resistance to insect pests, or for stock with resistance to RGS, or both. }, issn = {1176-5283}, author = {Young SR and Scobie DR and Morris CA and Amyes NC} } @conference {41428, title = {Wool yellowing and pH within Merino and Romney fleeces}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {63}, year = {2003}, month = {Jan}, pages = {155-159}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Queenstown}, abstract = {Fleece samples were taken from the back, side and belly of three adult ewes in one Merino flock and three adult ewes in one Romney flock in each of six regions of New Zealand (Waikato, Manawatu, Wairarapa, Marlborough, Canterbury, Otago). Each fleece was 12 months growth. These samples were used to compare factors associated with wool yellowing as measured by tristimulus (Y-Z) values. Neither the region of New Zealand where the sheep grazed nor the measured dimensional fleece characteristics, were related to fleece yellowing. The pH of an aqueous extract of greasy wool was strongly related (R2 = 0.93) to tristimulus (Y-Z) (base yellow) at shearing but less strongly related (R2 = 0.70) to tristimulus (Y-Z) after the sample had been incubated at 40{\textdegree}C and 100\% RH for 6 d. Merino samples had a lower tristimulus (Y-Z), both before and after incubation, at a particular pH than Romney samples. Back wool did not increase in yellowness as much during incubation as side or belly wool possibly on account of photo-oxidation following prolonged exposure to sunlight. These data indicate a close relationship between pH of a water soluble component of greasy wool and the extent of wool yellowing that was influenced by sheep breed and body site. }, issn = {1176-5283}, author = {Sumner RMW and Young SR and Upsdell MP} } @conference {41187, title = {The relationship between wool follicle density and fibre diameter is curvilinear}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {60}, year = {2000}, month = {Jan}, pages = {162-165}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {Records for wool follicle density and wool fibre diameter were obtained from ewes (n = 787) of 13 breeds and lambs (n = 543) of eight breeds and four crossbred combinations. The data were gathered as part of nine separate experiments from seven years. Mean fibre diameter ranged between 14 and 58 {\textmu}m, while follicle density covered the range 6.5 to 95 follicles/mm2. There was a significant curvilinear relationship (P < 0.001) between individual animal means for fibre diameter and follicle density. The relationship was significantly different between ewes and lambs (P< 0.001). Furthermore, the relationship between breed means for density and diameter were compared with equivalent data from literature sources. The relationship was effectively the same for all sources of data (P = 0.455). A restricted range of data could have led some literature sources to suggest a linear relationship! }, issn = {1176-5283}, author = {Scobie DR and Young SR} } @conference {40892, title = {Bulk and fibre diameter affect leather and woolskin quality of lamb skins}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {57}, year = {1997}, month = {Jan}, pages = {77-80}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Poll Dorset x Romney lambs were chosen from a group of 300 on the basis of measured diameter and bulk. The selected lambs made up four groups of twenty, that had the four possible combinations of low (LD) or high diameter (HD) (29 or 32 um), and low (LB) or high bulk (HB) (22 or 26 cm{\textthreesuperior}/g). Pelts were recovered at slaughter, assessed for woolskin tanning, processed to dyed crust leather and scored for the grain surface defect known as pinhole (1 to 5, best to worst). Suitability for woolskins was greatest for the high bulk groups (LDHB, 20; HDHB, 18), and least for the HDLB group (5), with the LDLB group intermediate (13). More pelts were found to exhibit pinhole in the high bulk groups (HDHB, 16; LDHB, 16 vs HDLB, 8; LDLB,10) and mean pinhole scores were higher (p <0.001) for these groups (HDHB, 2.5; LDHB, 2.4, vs LDLB, 1.7; HDLB, 1.5). Woolskins are a more appropriate product for finer and bulkier wool types, whereas less bulky wools of high diameter lend themselves to leather production, because they are unsuitable for woolskins and less prone to pinhole. }, issn = {1176-5283}, author = {Scobie DR and Cooper SM and Passman A and Young SR} } @conference {40599, title = {Variation in the pH of lamb meat within and between sheep breeds}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {54}, year = {1994}, month = {Jan}, pages = {201-204}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {Serial measurements of the pH of the longissimus dorsi muscle were obtained from lambs of 22 sire groups of six sire breeds (Experiment 1) and in 14 sire groups of lines selected for Fast and Slow Glucose Clearance (Experiment 2). Lamb sex (ewe, wether) and carcass weight and leanness had little effect on meat pH. Sire breed had significant effects on pH at 1 and 24 hours post mortem, and selection line had significant effects between 1 and 4 hours post mortem. These effects were greater on slaughter dates when pH levels were higher. Variation between individual sires was sufficient to account for some differences between sire breeds and selection lines. Differences between sire breeds and selection lines were found from the time of first pH measurement after slaughter through until ultimate pH was reached. This suggests that there were differences in the rate of glycogen breakdown to lactic acid immediately after slaughter or during electrical stimulation, as well as differences in the amount of glycogen in the muscle at slaughter. These findings confirm that lamb genotype can influence meat pH and thus will affect commercially important meat properties. }, issn = {1176-5283}, author = {Bray AR and Young SR and Scales GH} } @conference {39923, title = {The effects of lamb breed, slaughter age and sex on carcass fat depth and export grade}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {44}, year = {1984}, month = {Jan}, pages = {227-230}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {A least squares analysis of the weight of 15 individual export cuts from 808 carcasses of 20-month old steers identified significant effects of carcass weight, carcass fat measurements, carcass grade and sire breed on the weight of export cuts. Increasing carcass weight had a positive effect on cut weight but increasing carcass fatness had a variable effect on weight of cut. The weight of cut marketed with negligible subcutaneous fat (cube roll) decreased in weight by 7\% as carcass fat depth increase from 4 to 12 mm. In contrast a cut which included subcutaneous fat increased in weight by 15\% over the same fatness range. The data show that the most equitable pricing system (schedule) would take account of weight of individual cuts.}, issn = {1176-5283}, author = {Geenty KG and Young SR and Clarke JN and Wilson JA} } @conference {39882, title = {Seasonal wool production and staple strength of Romney ewes}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {44}, year = {1984}, month = {Jan}, pages = {57-60}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, abstract = {The average conception rate (CR) to first insemination in 1969- 70 was 60.6\% compared to 67.7\% in 1982-83. CR declined with increasing herd size in the latter study (from 70.5\% in herds of <101 cows to 66.0\% in herds of >300 cows), but this trend was substantially less than the former study (from 62.8\% to 52.3\%). The change in herd size effects was mainly due to improved accuracy in the detection of oestrus in larger herds probably associated with the use of tail paint. On average, 50\% of cows in 35 Waikato herds had calved by the end of a period of 18.3 d from the date of planned start of calving. The next 25\% of cows calved over a period of 17.5 d, and the last 25\% calved over 36.3 d. Consequently, the average calving covered 71.9 d from the planned start compared to 46 d in the Ruakura No.2 herd. A comparison with results from a 1972 survey showed that calving patterns had become more concentrated because of improved breeding management and the use of induced calving.}, issn = {1176-5283}, author = {Geenty KG and Orwin DFG and Woods JL and Young SR and Smith MC} }