Interplay between stress and reproduction: Novel epigenetic markers in response to shearing patterns in Australian Merino sheep (Ovis aries)

In this study, we determined the effect(s) of shearing on Australian Merino ewes (Ovis aries). To test this research question, we used a suite of field and laboratory methods including GPS collars, wool cortisol and novel epigenetic markers identified using Illumina NovaSeq RRBS. Single shorn ewes (n =24) kept on their full fleece throughout the entire gestation period while twice shorn ewes (n =24) had their wool shorn early in gestation. We have discovered one locus (Chr20:50404014) which was significantly associated with different shearing treatments (twice or single shorn ewes), (FDR = 0.005). This locus is upstream of a protein coding gene (ENSOARG00000002778.1), which shows similarities to the forkhead box C1 (FOXC1) mRNA using BLAST searches. We discovered that 36 gene loci were significantly modulated either between different shearing treatments or late vs early pregnancy ewes. Similarly, in lambs we identified 16 annotated gene loci that were significant between late vs early pregnancy. Early shorn ewes grazed 10% higher and maintained stronger body condition. Wool cortisol levels were significantly lower in the early shorn ewes during mid- and late gestation. Lambs bred from twice shorn ewes had on average better visual wool quality parameters in terms of micron, spin finesses and curvature. Collectively, this research provides a new dataset combining physiological, molecular epigenetics and digital tracking indices that advances our understanding of how Merino ewes respond to shearing frequency and this information could guide further research on sheep breeding and welfare.

Objective comparison of the softness of Australian Soft Rolling Skin wool and ordinary Merino wool

Australian Merino wool is well-known in the wool market for its top quality, and the bulk of it is used in apparel where softness is a key factor for consumers. However, the ethical issue of mulesing is driving textile manufacturers and retailers to purchase non-mulesed wool from other sources instead of Australian mulesed wool. Australian Soft Rolling Skin (SRS) wool, grown on non-mulesed sheep, has been perceived to have a softer handle than ordinary Merino (OM) of the same diameter. In this research, three different methods were deployed to objectively compare the softness of SRS and OM wool. The force required to pull a bundle of clean wool through a series of parallel pins, that is, the pulling force, was used to evaluate the combined effect of fiber bending rigidity and surface friction. SRS wool resulted in lower pulling force than OM wool, with a difference of 15 cN/ktex (approximately 12.5%). According to the Resistance to Compression test results, SRS wool (4.5–5.7 kPa) was easier to compress than OM wool (5.4–6.5 kPa). The modified Resistance to Compression method showed different compression profiles for the two types of wool, and the slope of the decreasing curve (SDC) was used to study the softness property, with lower SDC values representing softer handle. These results confirm that over a fixed diameter range the SRS wool was more compressible and flexible, and this should result in a softer handle for clothing made from the fiber.

Effect of Gastrointestinal Nematodes on Reproduction and Lamb Growth in Australian Merino Sheep

Environmental conditions in Uruguay favour the development of gastrointestinal nematodes (GIN) throughout the year, with clinical or subclinical manifestations that cause significant economic losses. The aim of this study was to evaluate the effect of the GIN on fertility, fecundity, reproductive rate and lamb growth in Australian Merino sheep grazing on basalt fields. The study was carried out in a farm located in north of Uruguay. Sixty-eight Merino ewes facing a natural parasite challenge were divided into two groups. Control group was doused with active anthelmintic that have proven efficacy to minimize the effects of parasitic and the parasitized group that did not receive anthelmintic, except rescue dosages. Stool sample of each sheep was collected monthly for egg counts (EPG) of GIN using McMaster technique and nematode genders were identified from infective larvae obtained in cultures by Roberts O’ Sullivan technique. Artificial insemination and ewes were mated for new service, and pregnancy condition was diagnosed by ultrasound. Lambing control was made and lambs were weighed at birth and marking. The evolution of EPG values showed significant differences between groups at the end of gestation and lactation. Haemonchus spp. was the main gender of nematodes found, followed by Trichostrongylus spp. Fertility was 95 % versus 90 %; fecundity 87 % versus 63 % and reproductive rate 73 % versus 47 % for the control group and the parasitized one respectively. No significant differences were recorded in birth-weight. However market-weight and lamb daily gain were lower in the parasitized group. The effect of natural infection GIN was evident in lower reproductive performance of Australian Merino sheep.

Estimation of lamb deaths within 5 days of birth associated with cold weather

In eight Australian Merino and crossbred sheep flocks, all lamb deaths were recorded, together with the corresponding weather before and after each case. Deaths on the day of birth were not strongly associated with a high chill index, but deaths in the following 3 days were significantly increased by a high chill index in the period between birth and the relevant day. Losses were greater for multiple-born lambs than singles under all conditions, but there was not a significant interaction of chill index with multiple births. A model is given for the risk of loss of lambs after birth, on the basis of birthweight, sex of the lamb, multiple birth and chill index for the ewe before birth and the lamb after birth. However, some of this information is not available until after the lamb is born, so a model is also given using only information available shortly before birth, namely, the expected chill index and whether pregnancy scanning has identified single or multiple lambs.