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The yak is critical for the life and economic activity of the people on the vast and inhospitable Qinghai-Tibetan plateau and on the surrounding mountainous areas. This article gives an overview of the domestication, the geographical distribution, the herding practices, the production and the products of the yak. Its breeding and hybridization management, as well as its reproduction and its special adaptation attributes are reviewed. Concluding thoughts about the role of the research and the role of social changes - driven from within or imposed from above - on the future of yak production systems are outlined. Cet article présente une vue d’ensemble de l’élevage du yak. Cet animal joue un rôle central dans la vie et l’activité économique sur les hauts plateaux inhospitaliers du Qinghai-Tibet et dans les massifs montagneux environnants. L’article présente les principales caractéristiques de la distribution géographique du yak, de son élevage, de son adaptation à cet environnement si difficile et de ses productions, ainsi que de sa reproduction et de son hybridation. L’auteur développe ensuite quelques réflexions sur les enjeux de recherche et sur le rôle que peuvent avoir les changements sociaux qui s’annoncent dans ces territoires d’altitude sur le devenir des systèmes d’élevage.

14-15 million yak (Poephagus grunniens, or Bos grunniens) provide the mainstay of life of several million people in the vast plateau (approx. 3 million sq. km) on “the roof of the world” - the provinces of Tibet, Qinghai, Sichuan and Gansu in western China, with the largest populations. Other provinces of China and countries, including Nepal, India, Bhutan, Mongolia (0.5 million yak) and some of the Russian Federation have smaller, but locally important populations. A small herd has existed at Whipsnade Wild Animal Park in England for about half a century and a population of 2-3 thousand has now grown in North America.

SUMMARYTwo surveys were conducted on commercial farms in England, Wales and Scotland to ascertain whether breeding contributed to variation in the number of lambs born per ewe, in lamb mortality and in the number of lambs remaining to be weaned per ewe. Each flock comprised two or more breed groups, but within flocks differences in breed were often quite small.In one survey of 74 flocks (average size 198 ewes, comprising 175 breed groups) the lambing percentage averaged around 150% and the lamb deaths to weaning (including stillbirths) around 9%. Within flocks there were statistically significant differences in the number of lambs born and weaned per ewe attributable to the breed of lamb and of its dam and sire. Crossbreeding was associated with a higher weaning percentage. Lamb mortality differed significantly among breeds and crosses of lamb. Lambing performance varied with type of farm.The second survey was a comparison of different crossbred types of dam, themselves the offspring of three breeds of sire and seven of ewe. Thirty flocks participated, providing 29 sets of records for 1-yearold females producing on average 120% lambs and losing through death (including stillbirths) 25 % of lambs born, and 10 sets at 2 years old, with 176 lambs per 100 ewes lambing and 11 % of the lambs born dying before 8 weeks old. Variation attributable to the crossbred type of the dam and to the breed of the dam's sire was significant for lambing and weaning percentage and the incidence of lamb mortality.

Evidence is reviewed of genetic variation in the incidence of disorders associated with the metabolism of minerals in general and trace elements in particular. Also reviewed is the evidence for genetic variation in the concentrations of various minerals and trace elements in blood and tissues of animals. Particular illustrations are given from work involving copper in sheep. The evidence suggests that breeds and strains of animals differ in their nutrient requirements for trace elements, and probably other minerals, for the prevention of disorder and possibly for optimum performance.

Studies by Honzik (4), Kagan (6), and Sontag (ii) are among the few which have correlated IQ changes with personality traits or parental behavior. A larger number of studies, as reviewed by Jones (5), suggest that IQ changes are correlated with social class variables. Some of these studies have been criticized by McNemar (8) because they did not adequately control for statistical regression: extreme IQ scores will tend toward the mean on later testing, partly as a function of an unreliable measuring instrument. This report is a preliminary attempt to indicate that IQ changes are not the result of statistical regression alone, but correlate with neurological status, socioeconomic background, and emotional stability.

Data from 100277 certificates of livebirths were analyzed in an attempt to uncover independent correlates of birthweight and gestation time. Without statistical control each of these variables was shown to be significantly related to race trimester of obtaining prenatal care maternal age parity socioeconomic status and legitimacy status. Regression analyses indicated that maternal race and the trimester in which she obtained prenatal care were the most significant correlates of birthweight and gestation time. It was suggested that race and trimester of obtaining prenatal care were not in themselves causes of low birthweight. Other indicess of socioeconomic cultural biological medical and psychological factors may be correlated with mothers race and the trimester in which she obtains prenatal care. (authors modified)

SUMMARYChanges in the concentration of copper in the blood of 241 adult ewes bled 4 times over a 12-month period (and 332 ewes over a shorter period) were analysed to examine sources of variation in the changes. Breed, age and swayback history were the most significant of the factors associated with both the amount and rate of decline in copper level from summer through autumn to winter. The number of lambs born, age of ewe, and swayback history were the most significant factors associated with the increase in levels from winter to the following summer.There was a tendency for the classes of sheep with the relatively higher concentrations of copper in their blood to show less seasonal fluctuation in those levels than classes of sheep with relatively lower concentrations of copper.

SUMMARYThe incidence of swayback among lambs in two flocks, previously reported, was reanalysed by a specially developed modification of the probit analysis technique in order to allow for the joint complications of an all-or-none trait and a large number of possible classifications for the animals in each flock. The form of analysis described yields predictions of the probability of swayback among lambs for the given circumstances.Breed and sire within breed each affected the probability appreciably even when allowance for live weight of ewe and lamb was made. The effects of live weight, though significant in each flock, were not consistent in direction between the flocks. Other significant factors affecting swayback incidence were the manner of rearing the lambs, week of birth, and, in one flock, the sex of the lamb.

SUMMARYConcentrations of Cu, Ca, P, Mg, K and Na were examined in the blood plasma (whole blood for P) of 149 adult ewes and their 244, 15-week-old lambs in a grassland flock of sheep. The ewes were 3 or 4 years old and of five crossbred types produced by mating Scottish Blackface females to Border Leicester, dun Forest, Dorset Horn, Finnish Landrace and Tasmanian Merino rams. The lambs in turn were the offspring of these crossbred ewes, and two rams of each of the Oxford Down, Southdown, Soay breeds and one Cheviot ram.Breed of sire (but not sire within breed) was a significant source of variation in the concentration of all the minerals, except Na, in the blood of both ewes and lambs. Other factors considered were age of ewe and sex, birth type, type of rearing, and date of birth of lamb. None of these appeared to be significant sources of variation except that twins and triplets, if reared as such, had higher concentrations of Ca in their blood than lambs born and reared as singles; however the ewes with singles were on different pasture from those rearing 2–3 lambs. For the mineral levels in the blood of the lambs there was no significant interaction of breed of ram with cross-breed of ewe. The lambs had substantially higher concentrations of Cu and P in their blood than their mothers and also significantly higher concentrations of Ca, Mg and possibly K. This may not be attributable to age alone because the lambs and their mothers also differed in genotype.Heritability estimates based on parent-offspring regression were 0·4 ±0·14 for Cu and less than 0·2 for the other minerals.

SUMMARYThree-hundred and thirty-four female sheep of the Blackface, Cheviot and Welsh Mountain breeds and the crosses among these breeds kept as one flock at pasture were bled in September 1966. Concentrations of Ca, Mg, K, Na and Cl were determined on plasma and P on whole blood. Mean concentrations (mg/100 ml) were: Ca 9·65; P 5·54; Mg 2·02; K 23·2; Na 345; Cl 365; and coefficients of variation (%) 11·1, 18·1, 29·0, 10·5 6·7 and 2·3 respectively.Breed was a highly significant (P< 0·01) source of variation for Ca, P, Mg and Cl, but except for Mg, the contribution to the total variance was small (< 10 %). Average values for cross-bred ewes deviated significantly (P < 0–05) from those of pure-bred for Ca and P concentration. Live-weight, within class, had a small but significant effect on Ca and Mg concentration.The concentration of Ca and Mg declined very significantly with age of ewe, there was a similar trend for K, while P showed a slight but steady tendency to increase with age, and Cl showed a more erratic increase.For Ca, barren ewes had a lower concentration (– 0·44 mg/100 ml) than ewes with lambs whilst ewes with single lambs at birth had lower concentrations (– 0·35) than ewes with twins. Other factors with effects too large to be ignored (P< 0·1) were the interaction of breed x no. of lambs (K and Cl) and swayback history (Cl).

The flock books of fourteen Lowland breeds of sheep were examined to study flock size, flock age, the number and source of rams used, the extent to which flocks differ in genetic importance within their breeds, the effect of geographical location on flock attributes, and changes in breed organization over a period of time.All breeds taken together showed that 46% of the 2649 flocks involved had less than fifty breeding ewes and 15% had more than 200. 43% of flocks were less than 5 years old and 18% were over twenty. A third of all flocks used only one ram and 9% used five or more. All breeds were found to be arranged in a hierarchy such that only a small number of flocks in each breed supplied the majority of the rams and in particular the rams used by rambreeding flocks. The ‘top’ flocks were among the largest and oldest in each breed. Flocks in the ‘native’ region of each breed we e generally larger and older than those elsewhere, but for other flock attributes the differences between regions were more peculiar to breeds. The general pattern of breed organization appeared to apply at widely differing periods of time.

SUMMARYThe concentration of copper in the blood of more than 300 sheep of a grassland flock was determined on each of five occasions between May 1965 and June 1966. Six breed classes, Scottish Blackface, Cheviot and Welsh Mountain, and the three crosses among these breeds, were involved.Breeds differed significantly in blood copper concentration with the Blackface having consistently the lowest and the Welsh the highest values. Crossbred sheep showed marked heterosis. Their levels were mostly at or near to the concentration of the parental breed with the higher value. Within breeds there was a positive regression of blood copper level on live weight of ewe.Ewes which had produced lambs affected by swayback in 1964 had lower levels of copper in their blood than ewes which had produced normal lambs. The difference was significant and most marked in winter.Ewes which were barren had, subsequently, higher blood copper concentrations than ewes with lambs. Ewes with single lambs had on average slightly higher levels than those with twins (but not significantly so), however, the effect differed among the breeds. Blood copper levels differed significantly on most occasions with the week in which ewes lambed in relation to the date of bleeding. Age of ewe had significant effects on copper concentration only at one bleeding (January 1966).There was an indication that classes low in copper concentration, notably Blackfaces and mothers of swayback lambs, showed a relatively steeper decline in copper levels during the winter than did other sheep.

Longitudinal data from the Johns Hopkins Study of Premature Infants were analyzed to compare the postnatal mental development of small-for-dates infants with that of other low-birth-weight newborn infants. At ages 8 to 10 years the I.Q. scores in children of the two groups were not different. Infants who weighed more than 2,500 Gm. at birth and whose mothers reported a gestational period of less than 38 weeks had significantly lower I.Q. scores at ages 8 to 10 years than did the children who were reportedly born at term with birth weights exceeding 2,500 Gm.

SUMMARYTwo sets of correlations among blood mineral concentrations were calculated (1) those attributable to the effects of various factors (breed, age, lambing performance, etc.) and (2) those remaining (residual) when the effects of such factors had been removed as sources of variation in mineral concentration (the equivalent of correlations within subclasses).Correlations arising from breed differences in mineral concentrations were highest for Ca.P (– 0·81), Ca.Cu (0·83) and P.Cu (–0·95). Correlations consequent on changes with the age of the sheep were most marked for Ca.Mg (0·97, P < 0·01) and Cu.K (–0·92, P < 0·05) and approximately 0·8 (P < 0·1) for Ca.K, P.Mg, P.K and K.C1.Residual correlations were all below 0–2 (although seven of the twenty-one were statistically significant, P < 0·05) suggesting that within subclasses most of the variation in the concentration of anyjone mineral was independent of that in the other minerals. Simple and partial correlations were very similar in magnitude suggesting that the associations found between pairs of minerals were not attributable to joint co-variance with any of the other five minerals.As the sheep grew older, changes in the concentrations of Ca, P and Mg were significantly correlated with the increases in live weight. Within subclasses, differences among the sheep in live weight were significantly (P < 0·05) and positively correlated with differences in the concentrations of Ca (r, 0·11), Mg (0·13) and Cu (0·11).

Charts of 100 schizophrenic inpatients, of whom half deteriorated and half recovered, were rated on the Becker-Wittman and Phillips Prognostic Scales by a rater blind to the long-term follow-up. Scores on both scales were highly correlated with each other, with follow-up status, and with a process or nonprocess classification by an independent rater. Five factors extracted from a correlation matrix of scores on individual score items were similar to those prognostic variables previously described by others.

Extract: Five hundred low birth weight children and 492 full-term infants were seen when approximately 40 weeks of age for a pediatric-neurologic examination. Of these, 822 provided the data upon which this report is based. To each child, when eight to ten years of age, there was administered ten subtests of the Wechsler Intelligence Test for Children (WISC), the Bender Gestalt Test and the Wide Range Reading and Spelling Achievement Test. In addition, observations were recorded regarding speech articulation and complexity of grammar. The number of perseveration instances and indications of possible comprehension aphasia observed during the examinations were recorded. The Verbal IQ, Performance IQ and Full Scale IQ scores, as well as the independently obtained Bender Gestalt score, showed increasing impairment with decreasing birth weight. Approximately twice as large a proportion of low birth weight children as of control children fell into the IQ category (50–79) which is associated with special medical or educational needs. At the ages of six to seven years the results of the Stanford-Binet Test showed an IQ difference between the low birth weight and full-sized groups of 3.4 points (F = 7.77, 3 and 810 df, p < 0.001), whereas the WISC given at the ages of eight to ten years indicated an IQ difference of 4.9 points (F = 10.87, 3 and 810 df, p < 0.001) for the same samples of children. Of the twenty psychological measures used to assess development of those who had been premature, relative impairment on 16 were significantly associated with birth weight and one was nearly so at the 0.05 level of significance. When the effect of the presence of indicators of possible neurologic abnormality was removed by analysis of covariance, the statistical significance of the association with birth weight was reduced for each of the variables measured, and only six of the twenty remained with significant assocation. Speculation: Future research might profitably consider whether performance by adolescents of low birth weight is relatively impaired in scholastic situations. Also, recent research suggests that a low birth weight occurring in conjunction with long gestational periods, may significantly prejudice intellectual capacity. However, there are little longitudinal data regarding this.

BLOOD copper-levels are known to be associated with the incidence of swayback in lambs (see Barlow et al.)1. A sample of fifty-five ewes was bled some 6 weeks prior to lambing and almost a year after a 15 per cent incidence of swayback had occurred among the lambs in the flock from which these ewes were drawn. The flock consists of three breeds (Scottish Blackface, South Country Cheviot and Welsh Mountain) and the crosses between these breeds. The ewes belong to two breeding classes, outbred (F2) and 25 per cent inbred (I1), and to four parities. The choice of animals for bleeding took account of these subdivisions within this flock and of swayback history of the lambs born to ewes of parity 2 and more in 1964. Blood copper values were estimated by the method of Butler and Newman2.

"Full-term" is what we meant. I'm sorry for the error and can only hope that Dr. Setleis is the only one sensitive (or perceptive) enough to have been disturbed by it. However, it did provoke him into a spate of wit, so all was not lost. Once again, sorry.