One of the benefits of the genomics revolution for animal production will be knowledge of genes that can be used to select more profitable livestock. Although it is possible to use genetic markers linked to genes of economic importance, tests for the genes themselves will be much more successful. Consequently finding genes of economic importance to livestock will be a major research aim for the future. Most traits of economic importance are quantitative traits affected by many genes. Mutations at many genes (e.g. 500) and at many positions within a gene (e.g. 1000 coding and non-coding bases) can affect a typical quantitative trait. The effect of these mutations on phenotype is usually small (e.g. 0·1 standard deviation) but occasionally large. Many mutations are lost from the population through genetic drift and selection, so that polymorphisms exist at only a subset of the relevant genes (e.g. 100 genes). Finding these genes, that have relatively small effects, is more difficult than finding genes for a classical Mendellian trait but, as the genomic tools become more powerful, it is becoming feasible and some successes have already occurred. The standard approach is to map a quantitative trait loci (QTL) to a chromosome region using linkage and linkage disequilibrium. Then test polymorphisms in positional candidate genes for an effect on the trait. Tools such as genomic sequence, EST collections and comparative maps make this approach feasible. Candidate genes can be selected based on functional data such as gene expression obtained from microarrays. At present the gain in rate of genetic improvement from use of DNA-based tests for QTL is small, because selection without them is already quite accurate, not enough QTL have been identified and genotyping is too expensive. However, in the future, with many QTL identified and inexpensive genotyping combined with decreased generation intervals, large gains are possible.

Genetic parameters for pre-weaning live weights and ultrasonic scanning measurements were estimated from a flock of Scottish Blackface sheep undergoing an embryo transfer programme. Maternal environmental effects could be evaluated without confounding with maternal genetic effects because embryos were transferred to unrelated recipient ewes. The data for the study were collected over a 7-year period (1993-1999) and related to a conventional hill farming system. The data were from 1465 lambs, the progeny of 60 sires, 263 donors and 784 recipient ewes. The only exception to the conventional farming system was at mating time when embryos were collected from selected donor ewes, following superovulation, and transferred to unrelated recipient ewes. Maternal environmental effects were important for birth weight (BW), 4-week weight (W4) and weaning weight (WW) but of less importance for ultrasonic fat depth (UFD), muscle depth (UMD) and muscle width (UMW). The heritabilities of the pre-weaning weights were moderate (0·17 to 0·23). The heritabilities of UFD and UMD were 0·44 and 0·27 respectively and were higher than found in previous similar studies. The heritability of UMW was low, 0·06. The genetic and phenotypic correlations among the pre-weaning weight traits were positive and moderate. There was a positive genetic ( + 0·25) and phenotypic ( + 0·24) correlation between UFD and UMD. The phenotypic and genetic correlations between BW and W4 and the scanning traits (UFD, UMD and UMW) were close to zero, and the correlations of WW with UFD, UMD and UMW were positive. The results of this study clearly demonstrate the importance of maternal environmental effects for lamb weights up to weaning and also suggest that genetic improvement for carcass composition in some populations of extensively reared hill sheep could be achieved more rapidly than previously thought possible.

The effect of selection for high phenotypic value in the presence of a genotype by environment interaction (G ✕ E, i.e. genetic variation for environmental sensitivity) and an improving environment was studied in a simulation. Environmental sensitivity was evaluated by using reaction norms, which describe the phenotype expressed by a genotype as a function of the environment. Three types of reaction norms (linear, quadratic and sigmoid), and two selection schemes (mass selection and progeny test selection) were studied. Environmental sensitivity was measured as the weighted average of the absolute value of the first derivative of the reaction norm function. Results showed that environmental sensitivity increased in response to selection for high phenotypic value in the presence of G ✕ E and an improving environment when reaction norms were linear or quadratic. For sigmoid reaction norms, approximating threshold characters, environmental sensitivity increased within the environmental range encompassing the threshold. With mass selection and/or non-linear reaction norms, environmental sensitivity increased even without environmental change.

The quality of grilled steaks was assessed by experienced panellists in longissimus thoracis (LT), semitendinosus (St) and triceps brachii (TB) muscles of Aubrac, Charolais, Limousin and Salers breeds raised in two production systems: 15-, 19- and 24-month-old bulls and 4-, 6- and 8-year-old cull cows.

Scores for sensory ‘initial tenderness’, ‘overall tenderness’, ‘juiciness’, ‘residue after mastication’ and ‘flavour intensity’ for all 497 meats were pooled to derive three eating quality classes.

Meats from the bulls and cows and from the four breeds were evenly distributed among the three eating quality classes. The highest quality class, representing one third of all the meats, contained 45% of the LT, 35% of the TB and 21% of the St muscles and one third of the meats from the 8-year-old cull cows. The meats in this class tended to have finer fibres, a greater proportion of slow oxidative fibres, slower post-mortem glycolysis, lower connective tissue and higher fat contents than those in the lower classes.

Lipid content accounted for proportionately 0·56 of the variation in flavour intensity and pH at 3 h post mortem, 0·52 of the variation in tenderness due to muscle and slaughter age.

Considering both young bulls and cull cows together, tenderness was highest in the meats from 15-month-old bulls and low in the meats from the intermediate age groups, and flavour and juiciness was highest in the meats from the oldest animals from each production system.

Post-weaning growth rate in pigs is frequently poor and variable. Choice feeding may offer the opportunity to rectify this. In experiment 1, 24 mixed sex groups of 16 pigs weaned with an average weight of 6·8 kg were blocked on weaning weight and assigned at random to the following treatments: (A) starter diet (18·3 g/kg lysine and 16·6 MJ digestible energy (DE) per kg) for 11 days followed by link diet (15·0 g/kg lysine and 15·3 MJ DE per kg) to 27 days; (B) starter diet and link diet offered in a free choice to 27 days; and (C) starter diet and weaner diet (13·0 g/kg lysine and 14·3 MJ DE per kg) offered in a free choice to 27 days. In experiment 2, 66 pigs were weaned at 6·3 kg, blocked as individuals on sex and weight and were randomly assigned to treatments as in experiment 1. In experiment 3, 24 single sex groups of 16 pigs were formed from pigs weaned at 7·8 kg. The groups were blocked on the basis of weaning weight and randomly assigned to the following treatments: (A) starter diet for 11 days followed by link diet to 26 days, (B) starter diet and link diet offered in a free choice to 26 days and (C) starter diet and link diet offered in a free choice to 26 days with feeder position rotated twice weekly. In experiments 1 and 3 pigs were offered a common weaner diet (14·1 g/kg lysine and 14·4 MJ DE per kg) following the experimental period. In experiment 1, daily gain was 406, 410 and 397 g/day (s.e. 6·6; P > 0·05) and food coversion efficiency (FCE) was 1·24, 1·21 and 1·27 g/g (s.e. 0·01; P < 0·01) during the period from day 0 to 27 for treatments A, B and C, respectively. The proportion of the diet selected as starter diet was 0·20, 0·50 and 0·47 (s.e. 0·023; P < 0·001) for treatments A, B and C, respectively. Within-pen variation in pig weight was similar for all treatments at day 14, 27 and 56 (P > 0·05), respectively. In experiment 2, daily gain was 403, 436 and 394 g/day (s.e. 13·0; P = 0·07) and FCE was 1·19, 1·16 and 1·24 g/g (s.e. 0·02; P < 0·05) during the period from day 0 to 26 for treatments A, B and C, respectively. The proportion of the diet selected as starter diet was 0·20, 0·57 and 0·53 (s.e. 0·024; P < 0·001) for treatments A, B and C, respectively. In experiment 3, daily gain was 465, 486 and 488 g/day (s.e.9·4; P > 0·05) and FCE was 1·14, 1·11 and 1·07 g/g (s.e. 0·015; P < 0·01) during the period from day 0 to 26 for treatments A, B and C, respectively. The proportion of the diet selected as starter diet was 0·21, 0·49 and 0·55 (s.e. 0·022; P < 0·001) for treatments A, B and C, respectively. Pig weight at day 49 was 36·4, 37·1 and 37·3 kg (s.e. 0·27; P = 0·09). It was concluded from these experiments that choice feeding did improve pig performance when a choice of starter and link diet was offered.

Man-animal relationships are involved in the process of fox domestication. Handling being an important part of man-animal contacts, causes stress responses in farm-bred blue foxes. The purpose of this study was to determine how prenatal stress induced by handling pregnant vixens influences certain morphometric and hormonal parameters of adrenocortical and gonadal function in the prepubertal offspring. Blue fox females were subjected to daily handling sessions, each of 1 min, in the last trimester of pregnancy (term = 52 days). Plasma concentrations of ACTH, cortisol, progesterone, oestradiol and testosterone, as well as the in vitro adrenal and gonadal production of steroids were measured by radio-immunoassay in control (C, no. = 56) and prenatally stressed (PS, no. = 56) blue fox cubs of both sexes at the age of 6 to 7 months. Prenatal stress decreased plasma concentration of cortisol (C: 31·0 (s.e. 4·3) v. PS: 22·7(s.e. 1·6) ng/ml, P < 0·05) as well as progesterone (C: 1·00(s.e. 0·10) v. PS: 0·65(s.e. 0·05) ng/ml, P < 0·05) in female cubs. Prenatal stress did not cause any changes in adrenal or gonadal weights, plasma concentrations of testosterone or oestradiol, or in vitro adrenal or gonadal steroid production, in either sex. It is concluded that persistent handling of pregnant blue foxes did not affect the prepubertal development of the reproductive system but resulted in disregulation in the hypothalamic-pituitary-adrenal axis in the female offspring.

Using primiparous autumn-lambing ewes, this study investigated nutritional effects on (i) pulsatile LH secretion, (ii) responsiveness of the pituitary-ovarian axis to exogenous GnRH, and (iii) oestrus and ovarian cyclicity during the early post-partum period. At lambing (25 October ± 0·3 days), 32 primiparous ewes rearing 2·1 ± 0·04 lambs were equally allocated to four dietary treatments in a 2 ✕ 2 factorial designed experiment. Diets comprised ad libitum hay and 1·5 kg per ewe per day of one of four concentrates (12·5 MJ metabolizable energy per kg dry matter) containing either fibrous (F) or starchy (S) ingredients with (P) or without (O) the inclusion of 120 g/kg fish meal. Throughout the study (lambing to 17 December) ewe body condition score was assessed and ewes and their lambs were weighed at weekly intervals. Blood samples were obtained from all ewes to measure circulating concentrations of progesterone and oestrous behaviour was monitored using vasectomized rams. On day 12 post partum, blood samples were obtained from all ewes at 2-h intervals (09:00 to 17:00 h) to measure concentrations of insulin and urea nitrogen, and at 15-min intervals (09:00 to 21:00 h) to measure pulsatile LH secretion. All ewes received 25 i. v. injections of GnRH (250 ng GnRH in 2 ml 0·9% saline) at 2-h intervals commencing 4 h before the end of the 15-min blood sampling period and their ovaries were examined via laparoscopy on day 17 post partum. There was no effect of dietary treatment on ewe live weight or body condition score throughout the study but inclusion of fish meal in the ewe diet increased lamb growth (FP/SP 255 (s.e. 8·9) v. FO/SO 234 (s.e. 8·2) g/day, P < 0·05). Circulating concentrations of insulin on day 12 post partum were lower in ewes given the fibrous compared with the starchy diets (P < 0·05) while dietary inclusion of fish meal increased (P < 0·001) urea nitrogen. Pulsatile LH secretion on day 12 post partum was not affected by dietary treatment. For ewes on diets F P, FO, SP and SO, the numbers that experienced an LH surge during the period of GnRH administration were 1, 2, 1 and 0, and that ovulated by day 17 post partum were 3, 5, 0 and 5 (FP/SP v. FO/SO, P < 0·05) respectively. Dietary treatment did not affect the intervals from parturition to the onset of ovarian cyclicity or oestrus (overall means were 23 (s.e.1·0) days and 38 (s.e.1·6) days respectively) but ewes on the fibrous compared with the starchy diet had a higher (P < 0·05) incidence of short (≤ 10 days) first ovarian cycles. Results of this study, which involved young growing animals, demonstrate that (i) inclusion of fish meal in the ewe diet influenced the sensitivity of the pituitary-ovarian axis to exogenous GnRH, and (ii) a fibrous compared with a starchy diet was associated with an increased incidence of premature luteal regression.

The efficiency of vaginal electrical resistance (VER) measurements for oestrous detection was determined in four experiments. The mean VER during oestrus, metoestrus, dioestrus, pro-oestrus and anoestrus was 32·68±0·46, 41·26±1·17, 50·23±0·55, 43·52±0·54 and 55·86±0·57 ohms, respectively. There were significant (P < 0·01) differences between VERs at the different oestrous cycle stages, except those during pro-oestrus and metoestrus which were similar. Twelve cows were induced in oestrus using prostaglandin (PG) administration to study the changes in VER during the peri-oestrus period. VER values changed both on a within-day (P < 0·05) and day-today (P < 0·001) basis following PG administration. Of the eight cows that responded, all were classified as in oestrus by VER in comparison to five detected in oestrus by a teaser bull. There was a significant association between VER and probability of conception (P < 0·01). Conception rates were 84, 61 and 20% when animals were inseminated at VER ranges of 26 to 30, 31 to 35 and 36 to 40 ohms, respectively. In the final experiment VER was recorded each day at the time of milking in 22 cyclic cows for 60 days. Animals were inseminated when the VER declined below 35 ohms. Of these 22 cows five cows showed overt signs of oestrus and 11/22 (50%) became pregnant. Twenty-one days post AI, five cows returned to oestrus, based on low VER, whereas 17 continued to show a high VER but eight of these (8/17) were subsequently classified as non-cyclic. It is concluded that VER can effectively be used for oestrus detection and identification of the optimum time for insemination but has limited value for pregnancy diagnosis. Cows should be inseminated when a VER reading of less than 36 ohms is recorded.

A study was undertaken to examine the effect of level and type of supplement and changes in the chemical composition of herbage through the grazing season on herbage intake, animal performance and rumen characteristics with high-yielding dairy cows. Thirty-two high genetic merit dairy cows were allocated to one of four treatments in a two-phase change-over design experiment. The four treatments involved offering either high-fibre (HF) or high-starch (HS) supplements at either 5 or 10 kg dry matter (DM) per day. Animals rotationally grazed perennial ryegrass swards offered a daily herbage allowance of 23 kg DM. High levels of animal performance were maintained throughout the study with mean milk yields over the 21-week experimental period of 35·5 and 37·2 kg per cow per day on the 5- and 10-kg treatments respectively. Supplement type had no significant effect on herbage intake. Increasing the level of supplementation reduced herbage intake by 0·49 and 0·46 kg herbage DM per kg supplement DM and increased milk yield, with a milk yield response of 0·55 and 0·65 kg/kg supplement DM offered in phases 1 and 2. Supplement type had no significant effect on milk yield and milk butterfat content. However, in both phases 1 and 2, milk protein content was significantly higher with cows offered the HS supplement compared with the HF supplement, this being particularly evident at the higher level of supplementation. Supplement type also had marked effects on milk protein composition. These results indicate that high levels of performance can be achieved with dairy cows on grazed pasture with moderate levels of supplementation.

We determined milk intake and growth rate of fat-tailed Awassi ram lambs from birth to 30 days of age when sucking ewes that were grazing natural green pasture in the semi-arid Negev. The conversion of milk and energy intake to body mass and body solids gain in the lambs were calculated. Annual rainfall and, as a consequence, pasture availability were below average during the study. Body mass at birth was 4·22 (s.d. 0·71) kg and at 30 days was 12·10 (s.d.1·22) kg for an average daily gain of 256 (s.d.33) g/day. Of the 256 g/day, 100 (s.d.12·3) g/day were body solids, and for every unit body mass increase, proportionately 0·391 was body solids. Milk and energy intakes averaged 1·34 (s.d.0·23) l/day and 5·66 (s.d.0·97) MJ/day, respectively. The volume of milk intake per kg increase in body mass and body solids were 5·2 l and 13·4 l, respectively, whereas, the energy intake per kg increase in body mass and body solids were 22·1 MJ and 56·6 MJ, respectively. Of the total metabolizable milk energy intake, proportionately 0·46 was converted to body energy of the lamb. Although dry matter intake of the ewes was insufficient to prevent body mass loss, they produced sufficient milk to support a relatively high lamb growth rate, presumably by mobilizing fat reserves in the tail.

Five species of alpine pasture plants from the Pyrenees representing 3 botanical groups: grasses (Festuca eskia, Nardus stricta), forbs (Anthyllis vulneraria, Galium verum) and shrubs (Echinospartum horridum), were collected monthly from June to September and analysed for nitrogen (N) content, cell wall composition, in vitro enzymatic digestibility (DMDe) and volume of gas produced by microbial fermentation. Among the dicotyledenous varieties, A. vulneraria and G. verum showed the highest nutritive value whilst that of E. horridum was low due to high lignin content. Grasses showed moderate nutritive values in June rapidly decreasing thereafter. Nitrogen content and organic matter digestibility (OMDg) of A. vulneraria remained relatively constant through the sampling period whereas it abruptly decreased for remaining species from July. Gas production significantly differed among species during the first 48 h of microbial fermentation but not at later stages of fermentation. Collection date did not affect gas production before 24 h of incubation but significant differences were found thereafter with samples from June and July being more degraded than from August and September. Principal component analysis associated OMDg positively with N content and gas production and negatively with fibre content. Lignin proportion did not significantly correlate with gas production or with OMDg, suggesting that the degree of lignification is not the only factor affecting microbial fermentation but other factors such as lignin tissue locations may be involved. A. vulneraria has been revealed as very good forage with a high potential in extensive animal production systems. Both OMDg and DMDe methods seem more accurate than chemical analyses for evaluating forages at different stages of maturity.

An experiment was conducted to determine if molasses could be successfully used to administer dotriacontane (C32) and hexatriacontane (C36) n-alkane markers to steers and to compare this method with a commercially available intra-ruminal controlled release device (CRD). The experiment was conducted over two similar periods (runs) using 24 Brahman crossbred steers in each run to study the effect of marker delivery methods and tropical grass hay diets in a randomized complete block design with three replicates. All steers were housed individually in partially covered pens, received one of two buffel-grass hays (B20: 20-week regrowth; 0·72 g nitrogen (N) per 100 g and B8: 8-week regrowth; 1·11 g N per 100 g) and one of four marker delivery treatments (control: no marker; 200 mg/day of C32 and C36 n-alkanes from a CRD or offered three times (Ms ✕ 3) or five times (Ms ✕ 5) a day in molasses). Voluntary intake (VI) and dry matter digestibility (DMD) for diets differed (P < 0·001) with B8 greater than B20. There was no difference among marker treatments for VI but the control treatment had greater, unexplained and possibly spurious, DMD than the Ms ✕ 3 marker treatment. Although the recovery of n-alkanes was variable (0·84 to 1·05) adjacent odd- and even-chain n-alkanes were similar with no differences (P > 0·05) due to marker treatment or diet. The CRD supplied a consistent marker dose between 6 and 18 days after insertion. Deviation from the 24-h mean faecal concentration seldom varied more than 0·03 for the individual markers and 0·05 for C31/C32 and C33/C32 ratios for all treatments. Over all the n-alkanes studied, the between-day variation was less than the within-day variation. For instance, the average of subsamples taken at 06:00 h and 18:00 h was within proportionately 0·05 of the 10-day mean concentration for 0·38 and 0·25 of records for C32 and C36 markers, respectively. It was concluded that molasses containing C32 and C36 n-alkane markers and given either three or five times daily was as accurate as the commercial CRD in administering n-alkane markers to steers and provides a method of delivering n-alkanes over an extended period in grazing studies.

The rôle of body reserves stored during early pregnancy on the periparturient breakdown of resistance to nematode parasites was investigated. From the 35th day of pregnancy, 46 ewes were distributed in four groups and given access to a lucerne pelleted diet. Two groups were given food at maintenance (M and C) and the other two were offered food either ad libitum (H) or at 0·70 their maintenance requirements (L) in order to achieve three well differentiated levels of body reserves by the 90th day of pregnancy when backfat thickness reached a mean value of 10·6, 7·5, 7·4 and 5·0 mm for H, M, C, and L treatments respectively. After the 90th day of pregnancy all animals were given food at 50 g/kg live weight per day. All ewes in groups H, M and L received 5000 infective larvae per week (40% Teladorsagia circumcincta, 40% Trichostrongylus colubriformis, 20% Haemonchus contortus) from 5 weeks before to 3 weeks after lambing. The animals in group C remained as uninfected controls.

Host resistance, as measured by faecal egg counts, was significantly affected by the nutritional treatment established during early pregnancy, showing a mean excretion of 546, 766 and 1007 eggs per gram (e.p.g. ) for H, M, and L treatments, respectively, until 3 weeks post lambing. This response was accompanied by a significant effect on circulating eosinophils and better fed ewes showed a higher concentration with a maximum mean value of 10·1, 6·9, 5·5 and 4·0 cells per mm3 for H, M, L and C treatments, respectively, 2 weeks post infection. The effect of the worm infection per se was evident in that the lambs of the M treatment ewes grew at 0·90 of the rate of those in the control treatment (189 v. 213 g/day). Ad libitum feeding in early pregnancy appeared to sufficiently compensate for this depressive effect, with the H ewes producing lambs that grew at a rate similar to those of the C ewes (213 v. 213 g/day).

The results support the view that fat mass stored by ewes in early pregnancy is involved in the expression of immunity against gastro-intestinal nematode infection around parturition. Furthermore, the depressive effect of ewes’ infection on lambs’ growth rate can be overcome by increasing the plane of nutrition of their dams. These results have clear implications for grazing animals, particularly their nutritional management in early pregnancy and provide a simple management strategy in sustainable management systems.

Ten Hereford ✕ Friesian steers prepared with rumen, duodenal and ileal cannulae were offered ad libitum access to either grass (G), white clover (W) or red clover (R) silage or mixtures of the grass silage with the clover silages (GW and GR; 60: 40 dry matter (DM) basis). The experiment was conducted as a two-period change-over design within each clover treatment, with grass silage as an experimental control. The clover silages had higher concentrations of DM, nitrogen (N), and total fatty acids and lower concentrations of fibre (P < 0·05) than the grass silage. Rumen fermentation characteristics were similar between treatments apart from a slight elevation of n-butyric acid levels with white clover silage diets (P < 0·05). Duodenal flows of DM, organic matter (OM), total and microbial nitrogen (MN) were significantly higher (P < 0·05) with the white clover silage treatments compared with the grass silage diet. However there were no significant differences in the efficiency of microbial protein synthesis with a mean value of 27·1 g MN per kg OM apparently digested in the rumen. Duodenal flows of total fatty acids per unit intake were not significantly different, although there was a trend (P < 0·1) for increased flows with the white clover silage diets. Duodenal flows of cis-vaccenic acid (P < 0·01), linoleic acid (P < 0·05), α-linolenic acid (P < 0·05) and cis-9 trans-11 conjugated linoleic acid (CLA) (P < 0·05) were higher for the clover silages, particularly white clover silage. The increased flows of α-linolenic and linoleic acids remained significant after correcting for differences in DM intake. Biohydrogenation of linoleic (mean = 0·83) and α-linolenic (mean = 0·86) acids was extensive for all diets but the latter was significantly lower (P < 0·01) for the diets based on red clover silage. These results suggest potential for modifying the fatty acid composition of ruminant products by feeding clover silages.

Sheep rearing is a traditional occupation of about 85 000 shepherd families on the Deccan plateau in the Maharashtra State of India. They rear Deccani (D) sheep which usually bear only single lambs. Prolificacy is an important trait for the efficiency of meat producing sheep. It was decided to evaluate and utilize Indian sheep genetic resources with a view to improving the efficiency of sheep production on the Deccan plateau. A crossbreeding experiment was conducted over 4 years, using rams of the D, Bannur (B) and Garole (G) breeds and D and B ewes with the aim of developing recommendations for the appropriate breed combination of a likely composite. It was found that crossing with G reduces live weight and growth rates significantly compared with D but lambs sired by G rams were more resistant to naturally acquired gastro-intestinal nematode infections and to artificial challenge with Haemonchus contortus than those sired by D or B rams. The G breed, being from a humid environment is, however, not adapted to the semi-arid Deccan plateau. The higher productivity (in terms of weight of lamb weaned) of twin-bearing ewes compared with those bearing singles was evident even in extensive rearing conditions. The finding of increased resistance to gastro-intestinal nematodes in the G breed, which also carries a major gene for prolificacy, highlights the potential for inclusion of G in a composite breed. Negative effects on growth and survival from inclusion of the Garole need to be carefully managed.

The aim of this experiment was to determine the mechanisms involved in changes in the production of cashmere as a consequence of genetic selection. Skin follicle parameters and pattern of cashmere growth were compared in two selected lines of Scottish cashmere goats and a randomly bred control line. One line, the fine line, had been selected for low fibre diameter, and this had resulted in lower fibre diameter, but the weight of cashmere produced had also been reduced. Selection for fibre quantity and quality to give maximum financial return (the value line) had increased cashmere weight without a significant increase in cashmere diameter.

Skin follicle density and the ratio of secondary to primary follicles (S/P ratio) were measured at 5 months of age in 25 female kids from each line. The density of follicles in the value line was greater (P · 0.05) than that in the fine or control lines (means were 21·8, 19·8 and 20·1 follicles per mm2 respectively, s.e.d. 0.73). S/P ratio increased (P · 0.001) from control to fine to value lines (means were 6.5, 7.7 and 8.4 respectively, s.e.d. = 0.30).

The rate of cashmere growth (length), peak cashmere length, the duration of the cashmere growing period and dates of initiation and cessation of growth were measured in the same 25 goats from each line between 2 and 3 years of age. These traits were estimated from the regression of measurements of staple length taken at approximately 6-weekly intervals from the start of the growing period until peak staple length was reached. Measurements were made on the shoulder, mid side and hip. There was no difference in cashmere growth rate between the selection lines (average 0·29 (s.e. 0.006) mm/day). Cashmere growth started earliest in the value line and latest in the fine line but the date of cessation of growth was not different. This affected the duration of the growing period which was 183, 163 and 214 days (s.e.d. 9.6, P · 0.001) for the control, fine and value lines respectively. Peak staple length of cashmere was longest in the value line.

Increased weight of cashmere in the value line was brought about through an increase in the number of secondary follicles and by an increase in the length of cashmere due to an increase in the duration of the growing period.