Doe feeding and cashmere: goat nutrition research in Australia

Why feral goats suddenly mattered: goat nutrition research in Australia begins#

Goats reached Australia with early mariners and later escaped from settler flocks, spreading across the continent into a feral population the paper puts at between 1 and 3 million animals. For most of the twentieth century this herd was a management headache rather than an asset, trapped mainly to supply an export carcase market that opened in the early seventies.

That changed once researchers recognised that many feral goats were growing cashmere, a fine down fibre separate from the coarser outer hair. An export market for cashmere followed, and with it a demand for solid information on feeding and managing goats for fibre and meat under Australian conditions.

The gap was real. European research had worked out requirements for milking goats, and the Angora mohair goat had been studied in the USA and South Africa, feeding into a 1981 set of nutrient recommendations from the National Research Council in the USA. But nothing existed for cashmere growth specifically, and it was not clear whether those general recommendations applied to feral goats of mixed breeding grazing Australian pasture.

A collaborative project linking the University of Queensland with a NSW Department of Agriculture research station near Wollongbar got underway in 1980 to close that gap, and this paper draws together the nutritional findings from that work up to the mid-1980s. It sits in the RAAN Conference Proceedings collection, alongside other nutrition papers presented at the same meeting.

How the doe feeding trial was run#

At the Wollongbar site, does were scanned by ultrasound 60 days after conception to identify single or twin pregnancies, and 32 does, half of them carrying twins, were split into groups fed pelleted rations in pens during different windows of pregnancy: 60 to 90, 90 to 120, 120 to 150 and 120 to 180 days post conception. A separate group stayed at pasture throughout as a control, and all does returned to the same pasture once their penned feeding period ended.

Within each feeding window, does received either a high or low protein diet, fed either freely or restricted to 70% of free intake. This design let the researchers separate the effects of timing, protein level and overall intake on the doe and her kids.

Alongside the feeding trial, a related study examined skin follicle development in kids, tracking primary and secondary follicle density and the ratio between them from birth through to shearing at 301 days. Separate pen and grazing experiments measured post-weaning growth, digestion, carcase composition and seasonal patterns of intake, feeding into the wider picture this review presents.

Late pregnancy feeding paid off at birth and beyond#

Feeding does in the final month of pregnancy produced the heaviest kids at birth of any treatment group, and those kids stayed ahead of other kids right through to weaning and shearing. Energy intake, rather than protein, appeared to be the main driver of this response.

The practical stakes are significant given the paper's observation that kids born under 1.5 kg have low survivability, which places adequate late-pregnancy nutrition near the top of any goat management plan. The study was continuing at the time of writing to see whether this early advantage carries through to mature body weight and lifetime productivity, so the long-term payoff remains an open question.

Feed quantity and protein quality in the month after kidding also shaped milk production and kid growth at that stage, though it did not change how long lactation lasted. Feeding before kidding, by contrast, did not alter subsequent milk yield. Milk output was similar whether a doe carried one kid or two, which the authors suggest points to an opportunity: targeting extra feed at twin-bearing does specifically, to help lift survival and growth of both kids before weaning, a question taken further in a later paper in this index on improving doe nutrition before kidding.

What doe nutrition did, and didn't, do to cashmere follicles#

Cashmere is grown from secondary follicles in the skin, and earlier work in sheep showed primary follicles form early in pregnancy and secondary follicles somewhat later, with both pre-natal and post-natal nutrition able to disrupt that process. In Angora goats, secondary follicles are mostly laid down well before birth but are not fully fibre-bearing until several months afterward.

The cashmere-goat follicle study found primary follicle development essentially complete by birth, with secondary follicle maturation, the point at which fibre actually appears, starting just before birth and finishing by three months of age.

Moderate restriction of energy or protein during pregnancy did not noticeably change the pattern or extent of follicle development, and neither birth type (single or twin) nor sex affected final secondary follicle density. Whether more severe restriction, before or after birth, would have a bigger effect is not known from this work, and the analysis of interactions between sex, birth type and feeding treatment was still underway when the paper was written.

Post-weaning growth, digestion and carcase fat#

Growth rates measured at a south-east Queensland site and a northern NSW site showed kids growing well before weaning but struggling afterwards, particularly through autumn, even though pasture looked adequate in quantity and quality. Protein supplementation stopped weight loss in autumn but still did not produce real growth, despite regular drenching for worms and cobalt supplementation. Growth improved again in July and August. When the same kids were later offered rich grain-based rations indoors, away from parasite exposure, growth rates picked up and matched other goat breeds.

On digestion, goats held rumen ammonia at higher levels and retained rumen fluid longer than sheep fed the same mature Pangola grass hay, suggesting goats may process protein differently on poor-quality roughage. On good quality roughage, goats and sheep digested and used nutrients with similar efficiency, but on concentrate diets sheep turned feed into weight gain noticeably better, a gap the authors argue is mostly explained by sheep simply eating more rather than any underlying difference in digestion.

Carcase studies found that goats fed concentrate diets produced carcases with fat levels close to New Zealand wether lambs, carrying double the fat recorded for feral goats in an earlier New Zealand study, achieved at modest body weights of 25 to 27 kg and around a year of age. Females produced fatter carcases than males, and free feeding produced more fat than restricted feeding, a pattern also seen in cattle.

Seasonal growth cycles and the cashmere growth clock#

Kids and weaner goats showed a consistent seasonal dip in intake and growth around May and June, most pronounced in males, mirroring a pattern recorded elsewhere in male kids and attributed to reduced feed intake rather than breeding-season behaviour. Because deer and unimproved Soay sheep show daylength-driven growth cycles, the researchers tested whether goats behave similarly by holding weaner does and bucks on lucerne pellets under either natural daylight or continuous light for eight months. Growth and intake still dipped in May-June regardless of light regime, suggesting this particular seasonal slump was not simply a response to daylength.

Cashmere growth itself, however, is clearly photoperiodic. Growth starts around the summer solstice in December and peaks in length between June and August, with fleece composition (the ratio of cashmere to coarser hair) peaking slightly earlier, between May and June. Does that were pregnant the previous year reach their peak about a month later than non-pregnant does and bucks, and there is preliminary evidence that late pregnancy and early lactation overlapping with the main fibre-growth period can depress cashmere production, though this needs confirmation.

Fibre diameter stayed steady at 15 to 16 microns through most of the cycle and only rose during shedding, implying the finest fibres shed first. Under continuous light the whole growth-and-shedding cycle compressed, delivering more than two cycles a year instead of one, a finding with clear implications for shearing timing and potential yield.

Why extra protein barely moved cashmere yield#

In sheep, extra dietary protein or sulphur amino acids reliably lift wool growth, and a similar protein response has been reported in Angora goats growing mohair. Cashmere was a valuable fibre at the time of writing, so a similar lift in cashmere from extra protein would clearly have been worth pursuing.

Ash and Norton (1984) found total fibre growth rose with dietary protein in weanling goats, but another group found no significant cashmere response. The present authors report running numerous further trials with grazing goats supplemented with various protected and unprotected protein sources, and with methionine, without ever demonstrating a reliable cashmere response. A controlled pen trial comparing high quality lucerne pellets with low quality Pangola grass hay, fed freely to male and female weanlings from December to June, found no significant effect of diet or sex on cashmere growth, length or diameter, even though liveweight growth and intake differed sharply between treatments. Hair growth (the coarser fibre) did respond, being greater in males and on the better diet.

The authors reason that because goats produce only small amounts of cashmere, 50 to 500 g per year according to the paper, the protein cost of growing it is tiny, against a much larger share of dietary protein converted to wool in sheep, so protein supply would rarely become limiting. They conclude that cashmere growth is controlled mainly by hormonal signals tied to daylength rather than by nutrition, and flag a need for research into the hormones governing fibre initiation, growth and shedding. We think this is a reasonably well-supported conclusion given how many independent feeding trials returned the same null result, though it rests on goats that had not been selected for cashmere production, so more responsive stock might behave differently.

Grazing behaviour: goats as weed controllers and pasture competitors#

Goats are well known for selecting a broader range of plants than sheep, which the authors link to their reputation for surviving in landscapes already stripped by sheep and cattle grazing. Rather than treating this as purely destructive, the paper highlights goats as a practical tool against woody weeds: blackberries, briar, gorse, narrow-leaf hopbush, mulga regrowth, wattle, eucalyptus regrowth and groundsel are all listed as species goats have been used to control, alongside grass weeds such as serrated and poa tussock and several thistle species, a grazing-pressure question also touched on in a related paper on rangeland fragmentation and changing land use.

Preference studies add nuance. Angora goats grazing ryegrass and subterranean clover pastures preferentially ate grass over clover, and pastures grazed by sheep together with goats carried more clover in November (38%) than pastures grazed by sheep alone (14%), with sheep in the mixed system also producing more wool. Yet in tropical pastures studied with fistulated cattle, sheep and goats, goats behaved more like cattle than sheep, selecting legume over grass in both summer and autumn except for one particular clover type they consistently avoided, while sheep preferred grass throughout.

Stocking rate trials in southern Queensland, run over nine weeks on an oats and ryegrass pasture, found liveweight gain per head declined at a similar rate in both species as total stocking rate rose, whether grazed together or separately. Sheep, heavier to start with, grew faster in absolute terms, but once weight differences were accounted for they were only marginally ahead (10 to 13%) of the unselected goats. Goats carried higher worm burdens than sheep in this trial. Together with earlier Victorian work on Angora wethers and Merino sheep, these findings suggest goats should not be stocked more heavily than sheep on the same annual pasture, even though individual goats are lighter.

Sources and further reading#

• Trove library search: find a library that holds the paper
• Meat & Livestock Australia: red meat industry research and marketing body
• Australian Wool Innovation: wool industry research and marketing body
• Feedipedia animal feed database: an open-access database of animal feeds

Questions#

— The Livestock Library team