Livestock Research for Rural Development 22 (3) 2010 Notes to Authors LRRD Newsletter

Citation of this paper

Hair pulling in confined sheep fed a finely ground ration: case report

N P Chiezey

Animal Reproduction Research Programme, National Animal Production Research Institute,
P. M. B 1096 Shika. Zaria, Nigeria


Following manifestations of alopecia, hair pulling and diarrhea in a flock of confined sheep, an investigation was carried out in which clinical observations, and sample analysis were used in arriving at a diagnosis.  The animals consisted of 60 Yankasa rams aged between 6 -18 months, which were being conditioned for experimental purposes. They had been held indoors for a period of two months to acclimatize, and were being fed a finely ground 12.7% crude protein concentrate ration, hay and trace mineral salt.


Affected animals were seen to be loosing hair, some had diarrhoea and eventually two animals became recumbent and died. Post mortem revealed mats of hair strands in the rather fluid abomasal contents. Skin scrapings of other animals were negative for ectoparasites and faecal samples examinations yielded only the presence of a few coccidian oocysts (+).  No specific explanation for the symptoms was apparent and so a nutritional problem was suspected. The finely ground feed was changed, and replaced with a coarse one and hay supplied ad libitum. The problem abated and the bare skin patches returned to normal about two months after the diet was adjusted. Continual feeding of concentrate diets of fine particle size may have negative effects on animal health and performance

Key words: abnormal behaviour, feed grit size, hair - plucking


Hair or wool plucking is a form of abnormal behaviour which seems to occur only in animals confined in an artificial environment (Reinhardt 2005). Crowding within pens in experimental animals have been found to be contributory factors (Fraser 1995),  but the more commonly reported cause has been trace element deficiencies, in particular copper, zinc  cobalt, calcium, phosphorus, sodium chloride,  manganese,  as well as vitamin or a protein deficiency (Akgul et al 2000; Youde and  Huaitao 2001; Meyer and Lohse 2002 ). Hair-pulling behaviour can be both self-directed and partner-directed and the hair is not only pulled out but also ingested. Female animals have been found to show wool pulling significantly more often than males (Reinhardt 2005)


Animals usually start by picking the dung-soiled wool from the rear of another member of the flock that may be sick and may later extend the plucking to even healthy ones. There are usually no health problems which are associated with this problem in adult sheep, but the habit may have serious health consequences for lambs. Depraved appetite or licking of surface generally indicates a lack of some ingredient in the ration, dietetic errors, or it can be a vice or bad habit due to boredom but may be difficult to specifically diagnose. The identification and pre-emptive correction of husbandry deficiencies causing stress and nutritional imbalance when animals are reared intensively will help prevent the development of disease and bizarre behaviour in animals


This paper reports a case of hair plucking and alopecia in a flock of experimental rams as a result of small particle size of the ration fed and the intervention undertaken.


Materials and methods 

Case history


A progressive loss of hair was observed in a flock of 60 Yankasa rams aged between 6 -12 months, kept for experimental purposes at the Department of Parasitology/ Entomolgy, Faculty of Veterinary Medicine, Ahmadu Bello University, Zaria. They had been purchased in the open market and had been held indoors for a period of two months to acclimatize to indoor holding and feeding of concentrate. They were held in four groups 15 animals each in concrete floor pens. They were not allowed to graze but were given hay and a 12.7% crude protein supplement as shown in Table 1.

Table 1. Percentage composition of the ration fed to animals





Wheat offal


Groundnut cake


Dry Brewer’s grain,


Bone meal


Vitamin mineral premix


Crude Protein


Total Digestible Nitrogen


Hay, water, mineral salt blocks were also provided daily. The animals had been fed on the ration for about 30 days when the anomaly was observed.


Clinical signs


On clinical examination,   the exposed skin was in good condition with no evidence of itching or flaking. Some animals were seen to be loosing hair and others were seen to repeatedly bite off the hair from other sheep or their own bodies. Most of the biting occurred on younger or weak animals and occurred over the hip, and shoulder. Four of the animals were diarrhoeic and anorexic, and two later became recumbent, developed decupital ulcers on the exposed flanks and eventually died.


Sample collection


The skin of all the animals was examined for the presence of ectoparasites and skin scrapings taken with a sharp razor into separate polythene bags for mite examination using standard procedures.


Faecal samples were also collected directly from the rectum of each animal. The samples were examined for the presence of helminth eggs and coccidian oocysts using the method of MAFF (1977). Random blood samples were also taken from the animals for Packed cell volume (PCV) evaluation and to examine for blood parasites.  Animals that died were also sent for post mortem. Feed samples were also sent for examination and analysis.


Results and discussion 

Physical examination did not reveal any ectoparasites on the body of the animals and mites were not found in the skin scrapings. No helminth ova were found in the faecal analysis but few coccidian oocysts (+) were detected in a few animals. Blood samples showed that PCV ranged from 19- 35%, no blood parasite was detected.


Post mortem did not reveal any definitive diagnosis related to the plucking of hair but some fluid were present in the lungs and   mats of hair strands  were found in the rather fluid abomasal contents.


Animals were all treated with Amprol (Amprolium. Merck Sharp and Dohme) 35 mg / kg as well as Terramycin long acting (Oxtetracycline, Pfizer) 200 mg per 10 kg body weight; but a nutritional problem was suspected.   Physical examination of the feed showed that the feed texture was very fine. Apparently during processing of the feed the feed mill had assumed it was poultry ration. The condition was then tentatively diagnosed as a vice due to paucity of roughage in the diet. The ration being fed was discarded and a fresh one compounded and coarsely grounded so that it had lager particle size. Hay was also given ad libitum. The problem abated and the bare skin patches returned to normal at about two months after the diet was adjusted.


Parasites, toxic agents, metabolic disorders, and nutritional insufficiencies are important factors in the aetiology of alopecia in sheep but alopecia due to hair plucking observed in this report is distinct from that due to mange, lice and fungal infection where animals bite and rub their own wool and skin to relieve itching and from the more commonly observed alopecia due to zinc and copper deficiency in which there is growth retardation, starvation, swollen joints, stiff gait as well as parakeratosis ( Akgul et al 2000; Youde and Huaito 2001; Reinhadt 2005). Loss of hair such as was observed in this report is similar to what was reported in Merino sheep fed a drought ration of wheat  with   small particle size(Hunter and Pryor 1972; Hinds 1986; Stafford 1988) and in sheep which had a deficiency of roughage in the diet, (Fraser and Broom 1990),    Stafford (1988) had reported that  diets of small particle size did not stimulate rumination and so the sheep  may pseudo ruminate: they may regurgitate a bolus of forestomach contents, but the bolus material may be too fluid to evoke a bout of cud chewing. He proposed that sheep acquired the vice because the hours that sheep would normally spend ruminating,  about 6 -12 hours per day, was spent idling. This theory seems to adequately explain what happened in the animals investigated in this report. Hair plucking per se may not be of great consequence in adult animals but the lamb's system may not be able to handle the hair mats (William et al 2000). Hairballs (trichobezoars) may then form in the stomach causing obstructions, either of the reticulo-omasal orifice or further down the gastrointestinal tract Fine grinding of the feed may also increase the rate of passage through the rumen and so decrease digestibility and may dispose the animal to bloat. Colic, anaemia and even death are among the consequences leading to considerable economic losses.


In conclusion, when sheep have to be held indoors for any length of time as was the case in this report, the feed texture must allow for the physiological requirement of the animals to ruminate. Particle size of ground grain for ruminants should be an optimal geometric mean diameter-GMD  of 1150 to 1250 microns (Hutjens 2002) as compared to a GMD between 400 and 600 microns for poultry and pigs.


An optimal grit size would allow for the most efficient utilization of concentrate feed as well as prevent the development of a depraved appetite and formation of trichobezoars in ruminants.



I wish to acknowledge the help of Saleh Usman and Daniel Gimba of the Department of Veterinary Parasitology/Entomology in sample collection and analysis and the assistance of Professor N. N. Umunna in evaluating the feed.



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Received 14 January 2010; Accepted 15 February 2010; Published 1 March 2010

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