Market failures are the main cause of poor acknowledgement of the true impact of functional sheep traits on the management and economic performance of farms, which results in their omission from the breeding goal or the estimation of non-representative economic weights in the breeding goal. Consequently, stated-preference non-market valuation techniques, which recently emerged to mitigate these problems, are necessary to estimate economic weights for functional traits. The purpose of this paper is to present an example of the use of a choice experiment (CE) in the estimation of economic weights for sheep traits for the design of breeding goals. Through a questionnaire survey the preferences of sheep farmers are recorded and their marginal willingness to pay (MWTP) for 10 production and functional traits is estimated. Data are analysed using random parameter logit models. The results reveal unobserved preference heterogeneity for fertility, adaptability to grazing and resistance to disease, thus highlighting that these traits are appreciated differently by farmers, because their needs are diverse. Positive MWTP is found for Greek breeds, high milk production and lambs with low fat deposition, for which there is high demand in Greek markets. On the other hand, MWTP for the cheese-making ability of milk is negative, stemming from the fact that sheep milk prices in Greece are not formulated according to milk composition. In addition, farmers seem to understand differences between udder shapes and attribute different values to various types. This application of the CE method indicates that communication channels among farmers and breeders should be established in order to enhance market performance and to provide orientation to the design of breeding programmes. Non-market valuation can be used complementarily to market valuation techniques, in order to provide accurate estimates for production and functional traits.

To tackle the high prevalence of lameness, techniques to monitor cow locomotion are being developed in order to detect changes in cows’ locomotion due to lameness. Obviously, in such lameness detection systems, alerts should only respond to locomotion changes that are related to lameness. However, other environmental or cow factors can contribute to locomotion changes not related to lameness and hence, might cause false alerts. In this study the effects of wet surfaces, dark environment, age, production level, lactation and gestation stage on cow locomotion were investigated. Data was collected at Institute for Agricultural and Fisheries Research research farm (Melle, Belgium) during a 5-month period. The gait variables of 30 non-lame and healthy Holstein cows were automatically measured every day. In dark environments and on wet walking surfaces cows took shorter, more asymmetrical strides with less step overlap. In general, older cows had a more asymmetrical gait and they walked slower with more abduction. Lactation stage or gestation stage also showed significant association with asymmetrical and shorter gait and less step overlap probably due to the heavy calf in the uterus. Next, two lameness detection algorithms were developed to investigate the added value of environmental and cow data into detection models. One algorithm solely used locomotion variables and a second algorithm used the same locomotion variables and additional environmental and cow data. In the latter algorithm only age and lactation stage together with the locomotion variables were withheld during model building. When comparing the sensitivity for the detection of non-lame cows, sensitivity increased by 10% when the cow data was added in the algorithm (sensitivity was 70% and 80% for the first and second algorithm, respectively). Hence, the number of false alerts for lame cows that were actually non-lame, decreased. This pilot study shows that using knowledge on influencing factors on cow locomotion will help in reducing the number of false alerts for lameness detection systems under development. However, further research is necessary in order to better understand these and many other possible influencing factors (e.g. trimming, conformation) of non-lame and hence ‘normal’ locomotion in cows.

This paper examines a paradox at the centre of efforts to improve livestock production in sub-Saharan Africa. For decades livestock nutrition and animal food have been identified as critical constraints, yet producers have shown little interest in improved food technologies. The main argument is that the analyses highlighting nutrition and food as critical constraints have focused primarily on biological productivity, and are thus at odds with livestock producers’ perceptions. The paper concludes by suggesting that livestock research in Africa must taker greater account of different systems, situations and producers, as well as key characteristics of technology such as reliability and management flexibility.

Until the turn of the century, farmers in West Africa considered cotton to be the ‘white gold’ for their livelihoods. Large fluctuations in cotton prices have led farmers to innovate into other business including dairy. Yet the productivity of cows fed traditional diets is very poor, especially during the long dry season. This study combines earlier published results of farmer participatory experiments with simulation modelling to evaluate the lifetime productivity of cows under varying feeding strategies and the resulting economic performance at farm level. We compared the profitability of cotton production to the innovation of dairy. The results show that milk production of the West African Méré breed could be expanded if cows are supplemented and kept stall-fed during the dry season. This option seems to be profitable for better-off farmers, but whether dairy will replace (some of) the role of cotton as the white gold for these smallholder farmers will depend on the cross price elasticity of cotton and milk. Farmers may (partly) replace cotton production for fodder production to produce milk if the price of cotton remains poor (below US$0.35/kg) and the milk price relatively strong (higher than US$0.38/kg). Price ratios need to remain stable over several seasons given the investments required for a change in production strategy. Furthermore, farmers will only seize the opportunity to engage in dairy if marketing infrastructure and milk markets are further developed.

Muturu (Bos taunts) cattle had a higher density of sweat glands in the skin (2208/cm2) than N'Dama (Bos taurus) (1776/cm2) and White Fulani (Bos indicus) (1584/cm2) cattle. Mean gland volume was 10·46,4·95 and 3·06 × 106 μ3 and length/diameter ratio (shape) of the glands was 3·97, 3·85 and 3·15 in N'Dama, Muturu and White Fulani cattle respectively.

Results of similar studies with German Friesian cattle in the same environment gave a gland count of 1968/cm2, a mean gland volume of 14·1 × 106 μm3 and a length/diameter ratio of 5·73.

Sweat gland measurements were generally higher for Friesian cattle than for zebu cattle and cattle of indigenous Bos taurus breeds.

Regional differences in the parameters were generally significant. The relevance of the results to the adaptability of the various breeds of cattle to the tropical environment are discussed.

1. Three isocaloric diets containing 170, 210 or 231 g crude protein per kg were given at two levels, and offered ad libitum to entire and castrated male pigs growing from 20 to 70 kg live weight.

2. Between 20 and 45 kg, growth rate improved with each increase in level of feeding (P < 005) and, on the ad libitum treatment the food intake and growth performance of both entire and castrated pigs were similar. On the restricted feeding treatments the growth performance of entire, but not of castrated pigs, improved when dietary protein was raised from 170 to 210g/kg (P < 005).

3. During the live-weight periods 45 to 70 and 20 to 70kg, raising food intake improved growth rate (P < 005) but increased the food conversion ratio and carcass fat measurements at 70 kg (P < 0·05). However, food conversion ratio and the majority of carcass characteristics of entire pigs fed ad libitum were equivalent to those of castrated pigs fed at the lowest level.

4. Dietary protein level had no significant effect on growth performance from 20 to 70 kg or on carcass fat measurements at the latter weight. However, each increase in dietary protein in the live-weight period 45 to 70 kg depressed the performance of castrated pigs (P < 0·05) while that of entire pigs was reduced when the protein level of the diet was raised from 210 to 231 g/kg.

The effect of vitamin A (retinol) on ovine stearoyl-CoA desaturase (SCD) mRNA levels and fatty acid composition was investigated. Sheep adipose tissue explants were maintained in culture for 24 h in the presence of all-trans retinoic acid (RA). Tissue SCD mRNA levels were increased with 25 μmol/l RA but the levels of SCD mRNA in tissue treated with 100 μmol/l RA were not different from control. The effect of vitamin A supplement on SCD mRNA levels in vivo was then characterized: growing lambs were given a concentrate diet (2 kg/day) containing 0, 0.225, 1.125 and 3.375 mg vitamin A per kg diet for 21 days. Treatment resulted in a concentration-dependent increase in adipose tissue and liver SCD mRNA levels, although the greatest effect was seen in the liver. SCD mRNA levels were highest in tissue from animals given 0.225 mg vitamin A per kg diet and further increases in vitamin A supplementation were not accompanied by corresponding increases in SCD gene expression. Fatty acid composition was also determined. Overall, tissue from animals given vitamin A had greater levels of both palmitoleic and oleic acid relative to their precursors. These data clearly show that SCD gene expression in adipose tissue and liver is regulated by retinoic acid and the liver appears to be most responsive. However, although significant, the change in the proportion of oleic acid was only small indicating that dietary manipulation with vitamin A is not a suitable method for increasing the unsaturated fat content of sheep meat.

The overall aim of the present study was to analyse and compare organic beef cattle farming in Spain with intensive and conventional systems. An on-farm study comparing farm management practices and animal health was carried out. The study also focussed on a slaughterhouse analysis by comparing impacts on the safety and quality of the cattle products. Twenty-four organic and 26 conventional farms were inspected, and farmers responded to a questionnaire that covered all basic data on their husbandry practices, farm management, veterinary treatments and reproductive performance during 2007. Furthermore, data on the hygiene and quality of 244, 2596 and 3021 carcasses of calves from organic, intensive and conventional farms, respectively, were retrieved from the official yearbook (2007) of a slaughterhouse. Differences found between organic and conventional farms across the farm analysis did not substantially reflect differences between both farm types in the predominant diseases that usually occur on beef cattle farms. However, calves reared organically presented fewer condemnations at slaughter compared with intensive and to a lesser extent with conventionally reared calves. Carcass performance also reflected differences between farm type and breed and was not necessarily better in organic farms.

Fifteen Large White boars were randomly allocated to three groups of five pigs. The boars were slaughtered over a period of time at one of three live weights: group 1 (pork weight), 63 to 68 kg (mean age 141 days), group 2 (bacon weight), 90 to 97 kg (mean age 203 days) and group 3 (heavy weight), 121 to 133 kg (mean age 268 days). Testes, bulbourethral glands, submaxillary salivary glands, blood and thoracic fat were taken from each pig and the glands weighed and steroids determined in extracts of the submaxillary glands, blood plasma and fat. Testosterone and the boar taint steroid, 5a-androstenone (5a-androst-16-en-3-one) were measured in plasma by radioimmunoassay (RIA). 3a-androstenol (5a-androst-16-en-3a-ol) and 5a-androstenone were determined separately in submaxillary glands by gas-liquid chromatography and together semi-quantitatively by a colour reaction. 5a-androstenone was also determined in submaxillary glands by RIA and in fat by enzyme-linked immunosorbent assay. Mean somatic characteristics differed significantly between the groups, but due to the wide variation in steroid concentrations between individual boars, mean differences for steroid concentrations between groups were not significant.

Significant positive correlations were found in boars between bulbourethral gland weight, submaxillary gland weight, concentrations of 3a-androstenol and 5a-androstenone in the submaxillary gland and concentrations of free plasma 5a-androstenone and fat 5a-androstenone (P < 0·05). The application of a simple colour reaction to detect readily extractable 16-androstene steroids (16-androstenes) in submaxillary gland tissue is discussed in relation to other methods for determining boar taint.

Instrumental assessments and sensory tests were performed to evaluate the effects of diet and postmortem ageing time (1, 7 and 21 days) on beef quality. A total of 48 Friesian calves were randomly allocated to four dietary treatments: control, whole linseed (10% linseed), conjugated linoleic acid (CLA) (2% protected CLA), and whole linseed+CLA (10% linseed and 2% protected CLA). Animals were slaughtered at 458±16.6 kg live weight and 11 months of age. Ageing was more significant than diet on most instrumental parameters. Meat from linseed enriched diets had greater drip loss (P⩽0.001) and intramuscular fat (P⩽0.01) than meat from animals fed CLA. Beef aged for 7 and 21 days had lower cooking losses (P⩽0.01) and shear force (P⩽0.001) than beef aged for 1 day. Lightness was affected only by display time. The addition of CLA in the diet increased hue and yellowness, whereas the inclusion of linseed decreased these values, as well as increased redness. Linseed in the diet decreased fat odour (P⩽0.05), but increased beef (P⩽0.01) and liver (P⩽0.05) flavours. Meat aged for 21 days was significantly more rancid (P⩽0.001), even under vacuum storage. Several organoleptic properties were improved with the inclusion of linseed in the diet, whereas they remained unaffected by the inclusion of CLA.

In total, 20 multiparous Holstein-Friesian dairy cows received one of four diets in each of four periods of 28-day duration in a Latin square design to test the hypothesis that the inclusion of lucerne in the ration of high-yielding dairy cows would improve animal performance and milk fatty acid (FA) composition. All dietary treatments contained 0.55 : 0.45 forage to concentrates (dry matter (DM) basis), and within the forage component the proportion of lucerne (Medicago sativa), grass (Lolium perenne) and maize silage (Zea mays) was varied (DM basis): control (C)=0.4 : 0.6 grass : maize silage; L20=0.2 : 0.2 : 0.6 lucerne : grass : maize silage; L40=0.4 : 0.6 lucerne : maize silage; and L60=0.6 : 0.4 lucerne : maize silage. Diets were formulated to contain a similar CP and metabolisable protein content, with the reduction of soya bean meal and feed grade urea with increasing content of lucerne. Intake averaged 24.3 kg DM/day and was lowest in cows when fed L60 (P<0.01), but there was no effect of treatment on milk yield, milk fat or protein content, or live weight change, which averaged 40.9 kg/day, 41.0, 30.9 g/kg and 0.16 kg/day, respectively. Milk fat content of 18:2 c9 c12 and 18:3 c9 c12 c15 was increased (P<0.05) with increasing proportion of lucerne in the ration. Milk fat content of total polyunsaturated fatty acids was increased by 0.26 g/100 g in L60 compared with C. Plasma urea and β-hydroxybutyrate concentrations averaged 3.54 and 0.52 mmol/l, respectively, and were highest (P<0.001) in cows when fed L60 and lowest in C, but plasma glucose and total protein was not affected (P>0.05) by dietary treatment. Digestibility of DM, organic matter, CP and fibre decreased (P<0.01) with increasing content of lucerne in the diet, although fibre digestibility was similar in L40 and L60. It is concluded that first cut grass silage can be replaced with first cut lucerne silage without any detrimental effect on performance and an improvement in the milk FA profile, although intake and digestibility was lowest and plasma urea concentrations highest in cows when fed the highest level of inclusion of lucerne.

The welfare consequences of long-distance transportation of animals remain a controversial topic. Animals that stand for most of the long journey (especially if additional muscular activity is required to deal with postural instability) are at risk of developing fatigue. Previous observational studies of behaviour and physiology suggested either that sheep do not become markedly fatigued by long journeys or that previous methods did not adequately identify fatigue. A range of behavioural and physiological measures were made on eight pairs of sheep during and after treadmill exercise. Within each pair of sheep, a treatment sheep was walked on a treadmill at 0.5 m/s for up to 5 h or until the sheep voluntarily stopped exercising or showed other signs of reduced performance, and a control sheep was exercised for two 10-min periods on either side of the exercise period for the treatment sheep. With the exception of one sheep that only walked for 4.5 h, all treatment sheep walked for 5 h without apparent difficulty. After exercise, the plasma cortisol concentration of treatment sheep was significantly greater than that of control sheep. However, there were no significant treatment effects on plasma creatine kinase activity or blood lactate concentration. After 5 h of exercise, there was a proportionate decrease in the median frequency of the electromyogram recorded over the m. semitendinosus, and this was significantly different from control sheep. There was no evidence that treatment sheep lay down sooner or for longer after treadmill exercise than controls. In sheep tested in a maze to examine whether there was increased motivation to rest after exercise, there was no significant difference between the times taken by treatment and control sheep to obtain a food reward. Qualitative behavioural assessment of the sheep by a panel of observers identified two main dimensions of sheep demeanour, but among descriptors elicited from observers only one person used a term associated with fatigue. No significant difference was found between the scores of treatment and control sheep on these two demeanour dimensions. Thus, there was little evidence that prolonged gentle walking exercise fatigues sheep. Further development of methods to both repeatedly induce and to identify fatigue in sheep is required.

Selenium (Se), an essential micronutrient, is believed to enhance neutrophil functions. This study aimed to compare the effects of supplemented organic (Sel-Plex®) and inorganic (sodium selenite) Se on neutrophil functions in high-producing dairy cows, during the periparturient period. Twenty-five Holstein cows were randomly allocated to five dietary treatments as follows: control diet (basal diet without Se supplementation), IN 0.3 (basal diet supplemented with inorganic Se at 0.3 mg/kg dry matter (DM)), IN 0.5 (inorganic Se at 0.5 mg/kg DM), OR 0.3 (organic Se at 0.3 mg/kg DM) and OR 0.5 (organic Se at 0.5 mg/kg DM). Some evaluated parameters included neutrophil functions and plasma Se concentrations in cows and plasma Se concentrations in calves. Neutrophil phagocytosis did not significantly differ among the five groups. However, organic Se supplementation significantly increased (P < 0.01) the respiratory burst of neutrophils when compared to cows fed IN 0.3 and the control diet. In comparison to inorganic Se, neutrophil apoptosis was decreased (P < 0.01) when cows were fed organic Se or the control diets. These effects of organic Se on respiratory burst activities and apoptosis of neutrophils were in a dose-dependent manner. Calf plasma Se concentrations were higher (P < 0.05) when cows were fed OR 0.5 and IN 0.5.

Tissue depletion and repletion were investigated in 142 Scottish Blackface ewes using computed tomography (CT). Ewes of two ages (2 or 3 years) and differing reproductive status (barren, single- or twin-bearing) were studied through one annual production cycle to investigate mobilization of carcass fat (subcutaneous and inter-muscular), internal fat and muscle.

Ewes were CT scanned five times during the 1-year study period: pre-mating; pre-lambing; mid-lactation; weaning; pre-mating the following year. For each animal at each of the five scanning events cross-sectional CT scans were taken at five anatomical sites (ischium, hip, 5th lumbar vertebra, 2nd lumbar vertebra and 8th thoracic vertebra). CT images were analysed to yield areas of carcass fat, muscle and internal fat and total weights of these tissues were estimated at each scanning event using prediction equations derived from a separate calibration data set.

The results show that both carcass and internal fat depots were depleted during pregnancy and early lactation and repleted from mid-lactation to mating the following year. In proportionate terms, internal fat was most labile, but carcass fat contributed more to total weight change because it was a bigger fat depot. Subcutaneous fat was the largest and most labile of the carcass fat depots. Muscle reserves were depleted only when fat reserves had fallen to very low levels. Older ewes carried more carcass fat in total than younger ewes when reserves were low. Mobilization of tissue reserves in twin-bearing ewes was less than in single-bearing ewes, probably due to preferential feeding.

Oilseeds offer some protection to the access of ruminal microorganisms and may be an alternative to calcium salts of fatty acids (FA), which are not fully inert in the ruminal environment. This study aimed to evaluate the effects of different sources of FA supplementation on apparent total tract nutrient digestibility, milk yield and composition, and energy balance (EB) of cows during the transition period and early lactation. We compared diets rich in C18:2 and C18:3 FA. Multiparous Holstein cows were randomly assigned to receive one of the four diets: control (n=11); whole flaxseed (WF, n=10), 60 and 80 g/kg (diet dry matter (DM) basis) of WF during the prepartum and postpartum periods, respectively; whole raw soybeans (WS, n=10), 120 and 160 g/kg (diet DM basis) of WS during the prepartum and postpartum periods, respectively; and calcium salts of unsaturated fatty acids (CSFA, n=11), 24 and 32 g/kg (diet DM basis) of CSFA during the prepartum and postpartum periods, respectively. Dry cows fed WF had higher DM and net energy of lactation (NEL) intake than those fed WS or CSFA. The FA supplementation did not alter DM and NDF apparent total tract digestibility, dry cows fed WF exhibited greater NDF total tract digestion than cows fed WS or CSFA. Feeding WS instead of CSFA did not alter NEL intake and total tract digestion of nutrients, but increased milk fat yield and concentration. Calculated efficiency of milk yield was not altered by diets. FA supplementation increased EB during the postpartum period. Experimental diets increased long-chain FA (saturated and unsaturated FA) in milk. In addition, cows fed WS and CSFA had higher C18:1 trans-11 FA and C18:2 cis, and lower C18:3 FA in milk than those fed WF. Furthermore, cows fed CSFA had higher C18:1 trans-11 and cis-9, trans-11 FA than cows fed WS. Although supplemental C18:2 and C18:3 FA did not influence the milk yield of cows, they positively affected EB and increased unsaturated long-chain FA in milk fat.

1. Eight British Friesian and eight Jersey calves were fed fresh milk during the period from 3 days to 40 days of age, at two levels of feeding.

2. Energy and nitrogen balances were measured twice for each calf.

3. Fasting heat production (FHP) (MJ/day), which was measured on these occasions, was related to live weight (kg) by FHP = 0·435 W0·75. There was no significant difference in FHP/kg0·75 between the breeds but previous level of feeding and the duration of fast had significant effects.

4. The data for heat production, metabolizable energy (ME) intake and energy retention were interpreted to provide estimates of ‘true’ net energy required for maintenance of 0·23–0·27 MJ/kg0·75 daily.

5. Pooled values for ME required for maintenance and for the net efficiency of utilization of ME above maintenance were 0·39 or 0·42 MJ ME/kg0·75 daily, and 0·67 or 0·72 determined by simple or multiple regression techniques respectively; there were no significant differences between the breeds. Pooled values for the partial net efficiencies of utilization of ME for the synthesis of protein and fat were 0·54 and 0·79 respectively.

6. ME required above maintenance was estimated to be 11·3 and 13·6 MJ ME/kg of live-weight gain for the lower and higher rates of gain respectively.

7. A small experiment revealed no major differences between diets of milk alone or milk plus solid food, with regard to maintenance requirement or net efficiency of utilization of ME by calves.

Previous research has shown that piglets using the sow's more anterior teats tend to have greater average weight gains, but this difference is often slight in the first lactation and increases in subsequent lactations. In this study, 27 sows were used to determine whether this difference develops because of the piglets' preferential use of the anterior teats during the first lactation. In their first lactation, 14 sows had their anterior teats (pairs 1 to 3) and 13 sows had their posterior teats (pairs 4 to 7) covered so that the piglets could use only one end of the udder. In the second lactation, all the teats were left uncovered and the sucking positions and weight gains of the piglets were studied. Piglets in the second lactation showed the usual preference for anterior teats regardless of which teats had been used in the first lactation. Where the anterior teats had been covered in the first lactation, there was no difference in weight gain between anterior- and posterior-sucking piglets in the 1st week of the second lactation, but a degree of anterior superiority had developed by the 3rd week (P < 0·01). Where posterior teats had been covered in the first lactation, piglets using anterior teats showed substantially greater weight gains than those using posterior teats throughout the first 3 weeks of the second lactation (P < 0·001). Thus, non-use of a teat in the first lactation tended to reduce its productivity, at least in the early part of the next lactation. We conclude that previous non-use of posterior teats can contribute to their tendency for lower productivity, but the effect does not explain completely the greater piglet weight gains usually associated with using the anterior teats.

Alfalfa protein is poorly utilised by ruminants due to its rapid degradation in rumen. The objective of the study was to assess the influence of spraying tannic acid (TA) on chopped alfalfa hay on in vitro rumen fermentation and nitrogen (N) retention by sheep. Alfalfa hay with and without TA was fed to sheep to determine nutrient digestibility and N balance. TA was sprayed on chopped alfalfa at three concentrations to determine its effect on in vitro fermentation of dry matter (DM) and N balance in sheep. Final TA concentrations were 0, 30, 60 and 90 g TA per kg DM. The control was sprayed with the same amount of water but without TA. In vitro DM degradation and the production of gas, ammonium-N (NH4-N) and short-chain fatty acid (SCFA) were measured. TA-sprayed alfalfa and the control were fed to sheep to determine nutrient digestibility and N retention. Addition of TA had no influence on the extent and rate of gas production but significantly decreased NH4-N concentration at 30 (P < 0.05), 60 and 90 (P < 0.0001) g/kg DM. Addition of polyethylene glycol (PEG) to TA-sprayed alfalfa increased NH4-N to a level comparable to non-TA-sprayed alfalfa. Spraying of alfalfa with TA significantly decreased (P < 0.05) isovalerate but did not affect the total and individual SCFA acid production. Tannic acid significantly (P < 0.05) reduced in vitro true degradability of DM (IVTD) after 24 h incubation at levels of 60 and 90 g TA per kg DM. Neutral-detergent fibre digestibility (dNDF) after 24 h (P < 0.01), 60 and 90 (P < 0.0001) g TA per kg DM. The effect of TA on either IVTD or dNDF was not significant (P > 0.05) after 48 h of incubation. There was a strong linear relationship between percentage increase in gas production due to PEG and protein precipitation capacity (R2 = 0.94). N digestibility was significantly reduced with all three levels of TA additions. However, the proportion of urine-N to total N output was reduced by adding 60 g (P < 0.05) and 90 g (P < 0.01) TA per kg DM. Serum metabolites and liver enzymes were not affected by TA (P > 0.05). Higher faecal N as the TA level increased indicates incomplete dissociation of tannin–protein complexes post ruminally. Factors affecting dissociation of tannin–protein complexes need further study.

Coat and skin samples were taken monthly from three Wiltshire ewes for two years, and then fortnightly between the spring equinox and the autumn equinox of 1968.

The fleece comprised kemp and wool, having a weight of 1·1 kg and a length of 50 mm. In summer all the primary fibres had a latticed medulla, and although the secondaries were smaller than the primaries, they were relatively coarse and often medullated, over one-third having a latticed medulla at the peak period. The overall mean S/P ratio was 3·5.

Follicle development was studied in four lambs from birth to 84 days. Only 27% of the secondaries lacked fibres at birth, and all had fibres at 14 days. There was a trend of increasing medullation in the primary fibres. Shedding primary follicles were seen from birth onwards, and shedding secondaries from 28 days, although obvious casting of the birth coat did not begin until 84 days (at the beginning of June).

There was a basic seasonal cycle of follicle activity starting in March and lasting until September; inactivity began in September, reached 100%, and continued at this level until March. Subsidiary cycles suspected from the monthly samples were confirmed by the fortnightly samples. Thus peaks of inactivity in June and August separated three cycles of growth of two months duration. Only 80% of the primaries and 50% of the secondaries became inactive in June, with 50% of the primaries and 30% of the secondaries, in August.

This paper reports a paternal half sib analysis of data collected over 3 years to estimate additive genetic variance of growth between birth and 16 weeks in crossbred progeny derived from Down rams. The data were divided into two groups and pooled estimates of parameters obtained by two methods. The paternal half sib intra-class correlations varied between 0·017 and 0·057 depending on pooling group and method. It is suggested that such low correlations arise because (a) most of the lambs in the study were still sucking at slaughter, close to 16 weeks of age, and the trait measured is thus largely influenced by maternal milking ability (b) the selection practised in the Down breeds may have been effective and reduced genetic variation and (c) there is considerable inbreeding in the Down breeds.

In further analysis of data from four farms involving rams mated to more than one breed of ewe there was limited evidence of specific combining ability of growth between birth and 16 weeks of age for Welsh ewes compared to ewes of other breeds.