CASE NOTES

Reflections of an ethologist

Geoff Green, Livestock Health Ranger, New England LHPA

Posted Flock & Herd April 2013

Introduction

I have been asked to pass on to you some "pearls of wisdom" gleaned from my working life in the agricultural industries and in particular observations from my 23 years involved with ethological research. My time in research was spent with CSIRO as a research technician based at the Pastoral Research Laboratory, Armidale, working as part of a research unit headed by Dr Justin Lynch. The majority of our work was with sheep with excursions into research on cattle and wombats. Most of our sheep work was done with merinos with some small projects branching into work with the British breeds and merino crossbreds.

1. The interaction of foxes with lambing ewes

These observations were made as part of our work on peri-natal mortalities in lambs. Conventional wisdom has it that foxes rush into the lambing paddock and proceed to terrorise the flock, maul and kill the lambs, often only sampling the liver and/or kidneys of the lambs they kill. Many hours spent on night shift, sitting in a small shelter on top of a forty foot tower with a "night scope" (Image Intensifier) glued to my eye, presented a quite different scenario. While the rouge fox who kills for sport may well exist, all the foxes (in the order of 30 to 40 foxes over a number of years) I observed were simply out to find sufficient food for their nightly requirements. In a lambing paddock with a veritable smorgasbord of fresh food available, the preferred main dish appeared to be fresh live lamb recently separated from its mother, while an entree of afterbirth or liver/kidney from a dead lamb was quite acceptable. Sometimes the live lambs taken appeared permanently separated from their mothers and if these were distant from the flock they were quickly taken and removed from the paddock. However, in about 50% of cases the lambs taken were apparently viable lambs whose mother was temporarily distracted, usually giving birth to a second lamb or grooming the other member of a set of twins. At no time did I see a fox actually confront a ewe and take her lamb, they invariably took the lamb that was either permanently or temporarily unattended. If a fresh main course was not easily procured, a return to a cadaver was contemplated and in these cases the fox appeared to remember where it had seen a dead lamb earlier in the night.

When dogs move among a mob of sheep they do it with their tail up, head up and a definite bounce in their step. Consequently, the flock senses danger and is immediately on alert. In contrast, a fox moves in with head and tail at or below the horizontal, smooth steady gentle steps and a "don't mind me I am just out for a stroll" approach. Amazingly, the sheep are generally conned, even when the fox wanders up to a separated lamb, casually grabs it by the neck and exits stage left with dinner for itself and possibly the cubs waiting in the den. I have seen foxes sit patiently about 10 metres from a freshly lambed ewe waiting for her to pass the afterbirth or commence parturition of the second lamb, at which time the fox will purloin the afterbirth or the first born lamb while mother is busy producing the second lamb. In all of this, reaction from the ewe and disturbance of the flock is minimal.

2. Maligned Merinos

Our other work ranged from how merinos utilise very large paddocks in western NSW in both summer and winter, through the effects of shelter on pasture and animal production, adaptation to shearing in New England winters, utilisation of water and water turn-over rates of merinos and merino/Border Leicester cross sheep, to the effect of early experience on acceptance of drought feeding.

Through all this work I developed a great admiration for the intelligence and sheer toughness of the sheep, merinos in particular. Sheep are depicted widely as silly and often referred to as "maggot wagons" or "ground lice". The truth is that they are gregarious, highly intelligent, sensitive animals usually ruled by fear, who survive despite the management afforded to them and still return some of the best farm gross margins for properties on the tablelands.

i. Water conservation:

Of all the sheep breeds, the merino is unique in its ability to adapt to the vagaries of the Australian climate. In western NSW in summer, merinos can go for up to 3 days without returning to their watering point and under tablelands conditions we worked with a mob of ewes which had not been provided with drinking water for three years (including two lambings). Some of the amazing things we recorded in these sheep was their ability to reduce their urine output to one tenth of that of the control group, allowing their core body temperature to slowly rise to half a degree above normal through the heat of the day and to drop to point four of a degree below normal in the cool of the night. When water was not available the grazing patterns underwent quite dramatic changes with almost all grazing done at night when it was cool and there was often dew on the grass, coupled with an early morning "water harvest" when dew was at a maximum. This water harvest involved the sheep moving along the fence lines licking the water droplets from the wires, or a rapid "grazing" action where they licked the dew from the grass without actually ingesting any grass. When their water requirements were satisfied the licking turned to actual grazing which ceased for the day as the sun dried the dew from the pasture. When there was good rainfall leading to high pasture water levels and sometimes free water in the paddocks, grazing patterns and urine output equated to those of the control flock. Surprisingly, the sheep with restricted water access actually produced a small but significant increase in wool production over the three years of the trial.

ii. Poor reproductive performance:

Merinos have a poor reputation for their reproductive performance and it is my observation that this is much more aligned with management than with the inability of the animals to conceive and carry a foetus to full term. It is no great feat on the tablelands to manage a merino flock so that in excess of 95% are pregnant with somewhere around 120% of lambs in-utero. This can be achieved simply by ensuring that healthy ewes in at least score 2.5 condition are joined with similarly healthy rams and that adequate nutrition is maintained for the period of joining. Joining does not need to continue on and on as 90 to 95 % of the ewes which will conceive will do so in the first three weeks of joining, and so a three to four week joining is perfectly adequate for healthy well fed sheep.

The challenge for the merino breeder is to turn this conception rate into lambs weaned and in the approximately 8 month period from conception to weaning there are many hazards. The merino ewe is genetically programmed to be selfish, so that if the stress becomes too much, she will dump the lamb and preserve herself. "She who lambs and walks away lives to lamb another day!" This ability to cut the lamb off begins as early as the second trimester of pregnancy when some advisors will tell you it is safe to apply some nutritional stress to your ewes. It is never safe to put merino ewes under nutritional stress, it will lead to small birth-weights (and poor survival) or abortions. Merinos do not suffer from pregnancy toxaemia nearly as much as other sheep breeds, they simply sacrifice the lamb and move on. Again, at the time of parturition, unless things go well with the birth and nutrition is adequate the risk is that the ewe will save herself and the lamb will become collateral damage. Unlike crossbreds, merinos have trouble counting past one, so unless both lambs in a set of twins make the effort to keep mother's attention in the first few days of life, even under good conditions, she will be satisfied with a single lamb. Once past the peri-natal period when her lambs are up and mobile, merino mothers undergo a transition and take good care of their offspring, however if nutrition takes a sudden down turn, so does milk production with the innate selfishness being reasserted and lamb growth rates suffering.

iii. Easy supplementary feeding:

We aimed to define the minimum exposure of lambs to drought feeds while still with their experienced mothers, that would result in those lambs recognising the feed in subsequent years. We fed grain to experienced ewes and their naive lambs on only two occasions a few weeks before weaning (minimum age of the lambs was 10 weeks). These lambs did not receive any supplementary feed until they were 2 years old. Despite only a small number of the lambs taking interest in the feed when exposed as lambs, they all recognized the feed and ate immediately when offered the grain as two year olds. In contrast, the control flock which had not been exposed to grain as lambs, failed to recognize the grain as feed and in fact shied away from the grain trail and were typically difficult to introduce to the new feed.

Other work on teaching sheep to eat novel feeds clearly demonstrated the advantages of including experienced "teachers" in the flock with feed intake increased, and learning time and proportion of shy feeders markedly reduced when the teachers were present. Unsurprisingly the higher the teacher to student ratio the quicker the "students" began eating and the lower the number of shy feeders at the end of the teaching period.

3. Electronics and wombats

One member of our research unit was an electronics "whiz" and it was his job to provide us with the "gadgets" which allowed us to measure many of the parameters we wished to monitor. These marvelous toys included temperature sensing "pill transmitters" which could be implanted into the sheep to measure deep body temperature for our shearing adaptation and water restriction trials. These transmitters were also used by Dr Doug Fowler of NSW Department of Agriculture to measure scrotal temperatures of rams at Fowler's Gap research Station in Western NSW.

Tracking collars were also developed in conjunction with National Parks and Wildlife staff for use on dingoes and these were adapted for use on wombats in the Brindabella ranges near Canberra. As you can imagine, there are numerous challenges involved in building a tracking collar sturdy enough to be used on a wombat and then fitting the collar so that it will remain in place without adversely affecting the animal's behaviour. Ultimately, we settled on using a carefully constructed sturdy surcingle attached to the collar with three strategically placed straps, one dorsally between the shoulder blades and the other two along the chest under the arms. Of all the research animals I have worked with the wombats were the most patient and exhibited the least reaction to handling. Despite impressive dentition and a fabulous set of claws we never had a wombat try to bite or scratch us. After removal from the cage traps they would simply sit on my lap grumpily waiting while being fitted with their collars. Once released the wombat would stomp off into the forest for 30 to 40 metres and then having seemingly forgotten the recent trauma, would resume normal foraging behaviours.

References

Lynch JJ, Hinch GN and Adams DB (1992) The Behaviour of Sheep CSIRO Publications
Green GC, Elwin RL, Motterhead BE, Keogh RG and Lynch JJ (1984) Long term effects of early experience to supplementary feeding in sheep Proceedings of Australian Society Animal Production 15:373-375
Hinch GN, Lynch JJ, Elwin RL and Green GC (1990) Long term associations between Merino ewes and their offspring Applied Animal Behavioural Science 27:93-103