The effect of gradually replacing barley with swedes or potatoes on intake of digestible dry matter and on the volatile fatty acid (VFA) composition of liquor was measured in an experiment with eight female and four castrated male sheep approximately six months old. The total intake of digestible dry matter was greatest when rolled barley was given at two-thirds of estimated maximal intake and roots given ad libitum. The intake of digestible dry matter was reduced to 80% of the highest intake when all the barley was substituted with swedes and to 70% of the highest intake when all the barley was substituted with potatoes. Replacing barley with roots had little or no influence on VFA composition.

Integrated Multi-Trophic Aquaculture takes advantage of the mutualism between some detritivorous fish and phytoplankton. The fish recycle nutrients by consuming live (and dead) algae and provide the inorganic carbon to fuel the growth of live algae. In the meanwhile, algae purify the water and generate the oxygen required by fishes. Such mechanism stabilizes the functioning of an artificially recycling ecosystem, as exemplified by combining the euryhaline tilapia Sarotherodon melanotheron heudelotii and the unicellular alga Chlorella sp. Feed addition in this ecosystem results in faster fish growth but also in an increase in phytoplankton biomass, which must be limited. In the prototype described here, the algal population control is exerted by herbivorous zooplankton growing in a separate pond connected in parallel to the fish–algae ecosystem. The zooplankton production is then consumed by tilapia, particularly by the fry and juveniles, when water is returned to the main circuit. Chlorella sp. and Brachionus plicatilis are two planktonic species that have spontaneously colonized the brackish water of the prototype, which was set-up in Senegal along the Atlantic Ocean shoreline. In our system, water was entirely recycled and only evaporation was compensated (1.5% volume/day). Sediment, which accumulated in the zooplankton pond, was the only trophic cul-de-sac. The system was temporarily destabilized following an accidental rotifer invasion in the main circuit. This caused Chlorella disappearance and replacement by opportunist algae, not consumed by Brachionus. Following the entire consumption of the Brachionus population by tilapias, Chlorella predominated again. Our artificial ecosystem combining S. m. heudelotii, Chlorella and B. plicatilis thus appeared to be resilient. This farming system was operated over one year with a fish productivity of 1.85 kg/m2 per year during the cold season (January to April).

The general aim of our in vitro experiments was to study the role of the metabolic hormones leptin, ghrelin, obestatin and IGF-I and mitogen-activated protein kinase (MAPK)-dependent intracellular mechanisms in the control of nuclear maturation of porcine oocytes. For this purpose, porcine oocytes were isolated from the ovary and cultured in the presence of leptin, ghrelin, obestatin, IGF-I, MAPK blocker PD98059 and the combinations of hormones with PD98059. Proportions of matured oocytes (at metaphase II of meiosis, determined by DAPI staining) and of oocytes containing MAPK/ERK1-2 (determined by immunocytochemistry) were measured before and after culture. It was observed that the majority of oocytes isolated from the ovary before culture were immature and did not contain visible MAPK, but some oocytes were mature, and the majority of these oocytes contained MAPK. Incubation of oocytes resulted in a significant increase in the proportion of matured oocytes and in the percentage of oocytes containing MAPK in both the matured and not matured groups. Addition of IGF-I to the culture medium increased the proportion of matured oocytes, addition of leptin decreased it, and ghrelin and obestatin did not oocyte maturation. Addition of hormones did not affect the expression of MAPK in either immature or mature oocytes. PD98059, when given alone, suppressed the maturation and accumulation of MAPK in both mature and immature oocytes. When given together with hormones, PD98059 was able to reduce the stimulatory effect of IGF-I, to invert the inhibitory action of leptin to stimulatory and to induce the stimulatory action of ghrelin and obestatin on meiosis. IGF-I, ghrelin and obestatin, but not leptin, when given together with PD98059, increased the accumulation of MAPK in both immature and mature oocytes. Association of nuclear maturation and expression of MAPK in oocytes before, but not after culture, as well as the prevention of oocyte maturation by MAPK blocker suggests the involvement of MAPK-dependent intracellular mechanisms in the promotion of reinitiation, but not completion of meiosis. The effect of hormonal additions on meiosis of oocytes suggests that IGF-I is a stimulator, leptin can be an inhibitor, while ghrelin and obestatin probably do not control oocyte maturation. The ability of PD98059 to modify the effect of hormones on oocyte maturation and on MAPK expression suggests possible interference of hormones and MAPK-dependent intracellular mechanisms in oocytes. However, no influence of hormones on MAPK and lack of association between action of hormones and PD98059 on MAPK and meiosis suggest that MAPK is probably not a mediator of effect of IGF-I, leptin, ghrelin and obestatin on porcine oocyte nuclear maturation.

The use of tail chalk and estrus/heat expression scores (HEATSC) evaluation is instrumental in identifying cows with greater estrus expression and greater artificial insemination pregnancy rates (P/AI) in cows submitted to timed artificial insemination (TAI), and cows with low or no estrus expression present lower P/AI. It was intended in this study to improve the pregnancy rates in TAI for Bos indicus beef cows, and gonadotrophin-releasing hormone (GnRH) injection was hypothesized to increase pregnancy rates in a TAI program for cows submitted to progesterone–estradiol-based protocols with low or no estrus expression, evaluated by HEATSC. Cows (n= 2284) received a progesterone device and 2 mg estradiol benzoate, after 8 days the device was removed and 1 mg estradiol cypionate, 150 μg of d-cloprostenol and 300 IU equine chorionic gonadotropin was administered. All cows were marked with chalk and HEATSC evaluated (scales 1 to 3) at TAI performed on day 10. Animals with HEATSC1 and HEATSC2 (n= 937) received 100 μg de gonadorelin (GNRH group; n= 470), or 1 ml saline (Control group; n= 467), and cows with HEATSC3 (named HEAT group; n= 1347) received no additional treatment. The larger dominant follicle, evaluated on day 8and at TAI (day 10), was greater in HEAT group (P= 0.0145 and P <0.001, respectively). Corpus luteum (CL) area and progesterone concentration was evaluated on day 17, and CL area was larger in HEAT group, intermediary in Control and lower in GnRH group (Control= 2.68 cm2, GnRH= 2.37 cm2, HEAT group= 3.07 cm2, P <0.001). Greater progesterone concentrations were found in HEAT group than in Control and GnRH groups (Control= 4.74 ng/ml, GnRH= 4.29 ng/ml, HEAT group= 6.08 ng/ml, P<0.001). There was a difference in ovulation rate, greater in HEAT group than GnRH and Control groups (Control= 72.5%; GnRH= 81.25%; HEAT group= 90.71%; P= 0.0024). Artificial insemination pregnancy rates was greater in HEAT group (57.09% (769/1347) than in Control and GNRH groups, with positive effect of GnRH injection at the time of TAI in P/AI (Control= 36.18% (169/467), GnRH= 45.95% (216/470); P<0.0001). In conclusion, GnRH application in cows with low HEATSC (1 and 2) is a simple strategy, requiring no changes in TAI management to increase pregnancy rates in postpartum beef cows submitted to progesterone–estradiol-based TAI protocols, without reaching, however, the pregnancy rates of cows that demonstrate high estrus expression at the TAI.

Individual observations made in different weeks of lactation (WL) of live weight (LW, lb), milk yield (MY and FCM, lb/day), age (years) live-weight change (LWC, lb/day) and digestibility of the organic matter consumed (D, %) were used to produce models pre-dicting organic-matter intake (OMI, lb/day), digestibleorganic-matter intake (DOMI, lb/day) and faecal output (lb OM/day) in 72 grazing cows (Analysis A). Estimates of herbage availability (HA, lb dry matter/cow per day) applicable to 44 of the cows, together with the above variables were used in a similar manner (Analysis B). The multiple regression methods of analysis were applied solely to between-cow observations by selection of a single set of data from the many available for each cow.

FCM and LW0·73 gave better results than MY and LW, and together with age, were all significant variables for the prediction of the dependent variable. HA was not a significant source of variation, D was only effective in models of DOMI and faecal output, and stage of lactation was not considered a consistently useful variable. The application of the multiple regression technique to the problem of partition of nutrients and the prediction of intake is considered. Precision of prediction is discussed in terms of tolerance limits for predicted values, and it is concluded that the lack of accuracy of measurement of intake in the individual grazing cow is the major obstacle to the accurate prediction of intake in grazing cows.

This study evaluated the effects of supplemental low- and high-purity glycerine on silage intake, milk yield and composition, plasma metabolites and body condition score (BCS) in dairy cows. A total of 42 cows of the Swedish Red Breed, housed in individual tie stalls, were fed 0.25 kg of low- or high-purity glycerine on top of concentrate, twice daily, during the first 4 weeks of lactation. One-third of the cows acted as controls, receiving no glycerine. Silage was fed for ad libitum intake and concentrate was fed at restricted level of intake, about 6 kg/day for primiparous cows and 7 kg/day for multiparous cows. Feed refusals were weighed daily. Cows were milked twice daily, milk yield was recorded on four occasions per week and milk samples were collected simultaneously. Blood samples were drawn from the coccygeal vessel once a week. Low- and high-purity glycerine had no effect on silage or total dry matter intake (P = 0.38 and P = 0.75, respectively) or on BCS (P = 0.45). Cows fed high-purity glycerine tended to have higher milk yield than control cows (P = 0.06). Milk composition tended to differ among treatments. No main effects of treatment on concentration of glycerine (P = 0.44), glucose (P = 0.78), insulin (P = 0.33), non-esterified fatty acids (P = 0.33) and β-hydroxybutyrate (P = 0.15) in plasma. These data indicate that high-purity glycerine has the potential to increase milk yield, as well as enhance the milk protein concentration and milk fat + protein yield.

The effects of source of protein on performance and nitrogen metabolism were studied in pigs weaned at 21 days of age. All diets contained 190 g crude protein and 14·6 MJ digestible energy per kg, and had a similar essential amino acid composition. Sources of protein were a combination of soya bean meal, fish meal and dried skim milk which was compared with soya bean meal alone, or in combination with either fish meal or dried skim milk. Seven groups of pigs (four pigs per group) received each diet ad libitum until 56 days of age. Performance was similar with the combinations of sources of protein, but with soya bean meal alone, food intake and growth rate were reduced (P < 0·05), but food conversion efficiency was not affected. Nitrogen metabolism was studied in seven pigs per diet given a restricted intake. Under these conditions, protein source had no effect on performance or retention and apparent digestibility of nitrogen. Nitrogen retention increased (P < 0·05) between 35 and 49 days of age, and was affected by the duration of the balance period (P < 0·01). In a second experiment, imparting a fish-like odour to the diet with soya bean meal as the sole source of protein by the addition of a fish oil did not affect food intake or performance.

These results indicate that a mixture of protein supplements in the diet of pigs weaned at 21 days of age may be unnecessary.

An experiment was conducted to examine the digestible energy (DE) content for weanling pigs in a cohort of wheats grown in Western Australia, and to establish relationships between DE content and their chemical composition. The 3 ✕ 3 ✕ 2 factorial experiment examined the wheat variety (Arrino, Stiletto and Westonia), growing location (high, medium and low rainfall zone) and harvest year (1999 and 2000). Pigs (no. = 5 per diet) aged about 28 days were given a diet at a level of 0·05 ✕ live weight containing 900 g/kg of the wheat and an acid-insoluble ash marker for 10 days, with samples of faeces collected from each pig for the final 5 days. The average live weight of pigs was 6·6 (s.d. 0·77) kg. The DE content of wheats harvested in 1999 varied by up to 1·3 MJ/kg, while wheats harvested in 2000 varied by up to 1·8 MJ/kg. When the 2 years’ data were combined, the DE content ranged from 12·5 to 14·4 MJ/kg. Both the variety and growing region significantly influenced (P < 0·05, P < 0·001, respectively in year 1999; P < 0·001, P < 0·01, respectively in year 2000) the DE content of wheat. Also, DE content of wheat differed significantly due to growing season (P < 0·001). Correlation studies between chemical composition and DE content of the wheats found significant inverse relationships between DE content and total xylose (r = –0·719, P < 0·05), insoluble xylose (r = –0·742, P < 0·05), neutral-detergent fibre (r = –0·839, P < 0·01), total-P (r = –0·833, P < 0·01), and phytate-P (r = –0·753, P < 0·05) contents with the wheats harvested in 1999. However, such relationships were not significant (P > 0·05) with the wheats harvested in 2000. In addition, the precipitation level (mm) during the growing season of wheats was strongly correlated (r = –0·821, P < 0·01) to the DE content of wheat in year 1999, but was not correlated in 2000. The results indicate that the genetic and environmental conditions during the growth of wheat have a significant impact on the utilization of plant energy in weaner pigs, and that greater attention needs to be paid to these influences in the assignment of energy values for wheats given to weaner pigs.

Sheep blowfly strike (ovine cutaneous myiasis) is a widespread economic and welfare problem in sheep husbandry in many parts of the world. Strike incidence is determined by a complex interaction of fly abundance, host susceptibility and climate, combined with farmer husbandry and intervention strategies. Sheep farmers adopt a range of approaches to the type and timing of the management used for the control of blowfly strike, the rational basis for which is often not robust. Here a deterministic model, based on existing data relating to fly abundance, seasonal risk and strike incidence, is used to compare the variable costs associated with different strike management strategies. The model shows that not employing prophylactic treatment is the lowest cost strategy only where strike risk is low. In all other circumstances, prophylactic treatment incurs lower costs than not doing so, because the deaths associated with strike outweigh the costs of prophylactic treatment. Lamb treatment, in particular, has a substantial effect on strike and cost reduction, since lambs are the most abundant age-class of animals and are at the highest risk over the period when fly abundance is the greatest. Early-season treatment of ewes before shearing is also an important component of the lowest cost strategies, particularly when the blowfly season is extended. While the rational choice of the most appropriate strike management strategy is essential in the context of farm economics, welfare considerations lend added importance to treatment decisions that reduce strike incidence.

Lipomatous myopathy is a degenerative muscle pathology characterized by the substitution of muscle cells with adipose tissue, sporadically reported in cattle, pigs, and rarely in sheep, horses and dogs. This study investigated the pathology of this myopathy in 40 muscle samples collected from regularly slaughtered Piedmontese cattle living in Piedmont region (Italy). None of the animals showed clinical signs of muscular disease. Muscle specimens were submitted to histological and enzymatic investigations. Gross pathology revealed a different grade of infiltration of adipose tissue, involving multiple or single muscles. The most affected regions were the ventral abdomen and the shoulders, especially the cutaneous muscles and the muscles of the thoracic group. Morphological staining revealed an infiltration of adipose tissue varying in distribution and severity, changes in muscle fibre size and increased number of fibres with centrally located nuclei, suggesting muscle degeneration–regeneration. Necrosis and non-suppurative inflammatory cells were also seen. Furthermore, proliferation of connective tissue and non-specific myopathic changes were present. Chemical and physical characteristics of the affected tissue were also evaluated. The authors discuss about the aetiopathogenesis and classification of this muscle disorder whose histological lesions were similar to those reported in human dystrophies.

The deposition of body and subcutaneous fat was compared in two groups of fat-tailed sheep, the one group docked shortly after birth and the tails of the other left intact. The slightly heavier live and carcass weights of the latter animals could be accounted for almost entirely by their significantly heavier weights of caudal fat, there being no firm evidence in support of increased internal or subcutaneous fatty deposition following amputation of the cauda.

In two experiments, the effects of protected fat and fibre were studied in compound supplements for grazing dairy cows. The protected fat used consisted of calcium salts of long-chain fatty acids. In experiment 1, 17 cows (group S) were given 4 kg/day of a starchy compound and 17 (group F) 4 kg/day of a high-fibre compound containing protected fat for the first 4 weeks after turn-out to grass. No significant difference was found between groups in milk yield, but cows in group F produced milk with a higher fat content (42·6 g/kg) than did those in group S (37·1 g/kg; P < 0·01) and had higher yields of fat (0·88 v. 0·79 kg/day; (P < 0·05). In experiment 2, four groups of five cows were given 4 kg/day of starchy (S) or fibrous (F) compounds, with (P) or without (C) protected fat for the first 4 weeks after turn-out. After 4 weeks, treatments (starchy or fibrous, added fat or none) were reversed for a further period of 4 weeks. There was no significant effect on milk yield, milk protein yield, live-weight change or change in condition score, although cows on treatment SC tended to produce less milk and have greater gains in live weight and condition. For groups SC, FC, SP and FP respectively, milk fat yields (kg/day) were 0·86, 0·98, 0·99 and 1·06 (s.e.d. 0·06); milk protein contents (g/kg) were 34·4, 34·8, 34·2 and 33·0 (s.e.d. 0·68) and calculated milk energy outputs (MJ/day) were 67/2, 74·3, 74·4 and 76·6 (s.e.d. 3·04). It is concluded that substituting fibrous compounds for starchy compounds tends to increase milk fat content and yield; adding calcium salts of fatty acids to either type of compound significantly increases milk fat content and yield but tends to decrease milk protein content.

This study aimed at assessing the effect of the observation method (direct or from video) and the effect of the presence of an observer on the behavioural results in veal calves kept on a commercial farm. To evaluate the effect of the observation method, 20 pens (four to five calves per pen) were observed by an observer for 60 min (two observation sessions of 30 min) and video-recorded at the same time. To evaluate the effect of the presence of the observer in front of the pen, 24 pens were video-recorded on 4 consecutive days and an observer was present in front of each pen for 60 min (two observation sessions of 30 min) on the third day. Behaviour was recorded using instantaneous scan sampling. For the study of the observer's effect, the analysis was limited to the posture, abnormal oral behaviour and manipulation of substrates. The two observation methods gave similar results for the time spent standing, but different results for all other behaviours. The presence of an observer did not affect the behaviour of calves at day level; however, their behaviour was affected when the observer was actually present in front of the pens. A higher percentage of calves were standing and were manipulating substrate in the presence of the observer, but there was no effect on abnormal oral behaviour. In conclusion, direct observations are a more suitable observation method than observations from video recordings for detailed behaviours in veal calves. The presence of an observer has a short-term effect on certain behaviours of calves that will have to be taken into consideration when monitoring these behaviours.

The objective was to determine the effects of immunization against gonadotropin-releasing hormone on reproductive characteristics in boars. A total of 72 boars were used in a randomized design with three treatments: single immunization (SI) (10 weeks of age) or double immunization (DI) (10 and 15 weeks of age) with Improvest® and intact controls (no Improvest®; CNT) (n=24/group). At 10, 15, 20, 25 and 40 weeks of age, blood was collected and serum harvested to evaluate testosterone concentrations. Testosterone concentrations were less for DI boars compared with CNT boars and SI boars at 20 and 25 weeks (P<0.001), but not at 40 weeks of age. At week 25, 18 pigs (n=6/group) were sacrificed and testes were removed, weighed and measured, and seminiferous tubules were examined and scored using histological slides of testes parenchyma. A sample of neck fat was assessed for boar taint aroma. All testicular measurements and weights and seminiferous tubule scores were less for DI boars compared with SI and CNT boars (P<0.001). More (P<0.05) SI and CNT boars had detectable boar taint aroma than DI boars. Libido was assessed at 32, 36, 47, 60 and 63 weeks of age and semen collected at 60 weeks of age was analyzed for indicators of quality. There were no effects of treatment (P=0.41) or treatment by week (P=0.71) on libido. Semen volume, gel weight and total number of sperm cells, determined in a subset of boars (n=3/treatment), were not different among treatments. Sperm concentration was greater for DI than SI (P=0.01), and tended to be greater for DI compared with CNT (P=0.10). Sperm motility tended to be greater for DI boars compared with CNT boars (P=0.066). In conclusion, our results show that there are no long-term effects of immunocastration on reproductive characteristics in boars.

Plasma concentrations of growth hormone (GH) are elevated in sheep during undernutrition. The present study attempted to determine whether this increased secretion mediated nutritional effects on reproduction or wool growth, using sheep immunized against growth hormone-releasing hormone and given a low-quality, sub-maintenance diet. Immunization reduced plasma concentrations of GH at all times measured (P < 0·01), through reduced pulse frequency, reduced pulse amplitude, and reduced baseline concentrations. Plasma insulin-like growth factor-1 (1GF-1) was also reduced in the immunized sheep (P < 0·01). Despite this, rates of live-weight loss and wool growth were similar in immunized and control ewes. Plasma concentrations ofLH and FSH were also similar in immunized and control ewes, both during the late luteal phase and after ovariectomy and supplementation with oestradiol and progesterone. Numbers of ovarian follicles and corpora lutea were also unaffected by immunization. It is concluded that high endogenous concentrations of GH in sheep given food below maintenance are necessary to maintain plasma IGF-1, but do not affect the concentration of gonadotropins or ovarian follicular growth. Furthermore, rates of live-weight loss and the depression in wool growth in such animals were also independent of concentrations ofGH or IGF-1.

A well fermented grass silage was mixed with 9·3 g lactic acid per kg silage supplied either as the free acid (lactic acid) or partially neutralized to pH 5·2 with sodium hydroxide (sodium lactate) to give three dietary treatments. Treatment with lactic acid reduced silage pH (P < 0·05) from 4·03 to 3·80 and increased (P < 0·01) the amount of sodium hydroxide required to raise silage pH to 6·5 (neutralizing value) from 167 to 261 mmol/kg silage and osmolality (P < 0·01) from 712 to 854 mosmoljkg silage; sodium lactate treatment increased (P < 0·05) silage pH to 4·15 and osmolality (P < 0·01) to 964 mosmoljkg silage but did not change neutralizing value.

Wlien fed in a randomized-block design to either six intact lambs or to four rumen fistulated sheep lactic acid treatment reduced (P < 0·05) silage dry matter (DM) intake (g/kg weight0·75) from 34·7 to 27·8 for intact sheep and from 35·5 to 29·9 for fistulated sheep. Intakes of the sodium lactate-treated silage tended to be higher (39·2, intact and 40·1, fistulated sheep, g/kg weight0·75) than the control silage. Silage DM intake was correlated more closely with neutralizing value (r2 = 0·34) than pH (rz = 0·24).

Treatment of silage with lactic acid or sodium lactate did not change rumen pH, volatile fatty acid patterns or osmolality. Blood pH, pCO2 and bicarbonate concentrations were not changed by the diets offered and were within normal ranges. Urine acid-base balance was not affected by lactic acid treatment whereas urine pH, and bicarbonate and sodium excretion were (P < 0·01) increased by sodium lactate treatment of the silage.

The aim of this study was to evaluate secondary fibre shedding in relation to seasonal hormonal changes in young cashmere-bearing goats reared in southern Italy. We used 14 cashmere-bearing kids, seven males and seven females, of a Scottish breed-population of goats specialized in cashmere production. Monthly, a hair patch of 4 cm2 was clipped from both left and right mid sides alternately and cashmere length and its yield were determined. Blood samples were taken every 2 weeks and plasma was assayed for prolactin (PRL), growth hormone (GH), tri-iodothyronine (T3), thyroxine (T4), progesterone and testosterone. With the same frequency, animals were monitored for onset of moult. Our data indicate that in young cashmere goats at their first moult, secondary fibre shedding is a seasonal event that is strictly related to changes in photoperiod and that PRL has a pivotal rôle in regulating this phenomenon. This corresponds with findings in adults. The observation that both thyroid hormones and sex steroids varied seasonally suggests that they are involved in the regulation of the moult cycle, but their precise rôle remains to be elucidated. Our data also indicate that GH seems to be implicated in the control of the moult cycle. The finding that maximal fibre shedding occurred earlier in males than females could be ascribed to differences in GH levels and to the earlier increase in plasma concentration of PRL observed in males.

The effect of the origin of dietary fibre on digestion and caecal fermentation in the rabbit was studied independently of variations in the level of the different cell wall constituents (cellulose, lignin, etc.). Relationships between microbial activity and the digestion of nutrients were also evaluated over a 4-week growth period. Three experimental diets were given ad libitum from, weaning (28 days) to three groups of nine New Zealand White rabbits, subjected to caecal cannulation at 35 days of age with in-vivo digesta sampling at 6, 7, 8, 9 weeks of age. The diets were similar in their content of neutral-detergent fibre (NDF) (320 g/kg dry matter) and in the respective proportions of cell wall constituents (hemicelluloses (NDF - acid-detergent fibre (ADF)) = 0·54, cellulose (ADF -acid-detergent lignin (ADL)) = 0·37, lignin (ADL) = 0·09), but they differed by their main fibre origin: lucerne meal = diet LM, sunflower meal = diet SM, wheat straw = diet WS.

As a consequence of the similar fibre level, the dietary intake was similar among the diets. The NDF digestibility ivas 0·03 units lower for the diet SM, and led to a lower quantity of NDF degraded (3·7 g NDF per day per kg live weight) compared with LM and WS groups (5·0 g NDF per day per kg live weight). Significant variations in caecal volatile fatty acid (VFA) levels were observed between LM and WS, although the intake of nutrients was rather similar, therefore suggesting a direct effect of the botanical origin of fibre. Compared with LM and SM diets, a significantly lower caecal VFA level was found for the WS diet and was associated with a higher incidence of digestive disorders. In the WS diet, fibres that come from only one botanical origin (wheat straw and bran) may be unfavourable to caecal fermentation and to the health status. The ammonia level, the caecal pH and the proportions of the different VFAs were not affected by the diets.

The total VFA level showed a significant quadratic trend between 6 and 9 weeks of age, whereas the butyrate molar proportion showed a significant linear increase from 0·08 to almost 0·10. In parallel, the daily quantity of hemicellulose digested was positively correlated to the butyrate molar proportion (r = 0·884, P < 0·001), and negatively correlated to the caecal pH (r = -0·705, P = 0·022).

1. Estimates of the voluntary feed intake of three age groups of wether sheep on ryegrass and white clover pasture from July to October, 1962, were made by total collection of faeces and the use of local faecal nitrogen-digestibility regressions.

2. Average faecal output and intake of digestible organic matter (DOM) increased with age of the sheep. However, relative to body weight (W) or to W073, the aged sheep (5 years old), which did not change much in weight over the period, consumed only about two-thirds of the DOM consumed by the younger (sixteen- and four-month-old) growing sheep.

3. For the growing sheep intake was directly related to weight. Intake was calculated to be 24 W (kg.)–28 ±108 g. DOM per day.

4. The results are discussed in relation to the errors in estimation of digestibility. Comparison of the intake estimates with other published data suggests there was a high apparent maintenance requirement. The voluntary feed intakes observed, when expressed as g. dry matter per kg. W0–73, were somewhat higher for young sheep but lower for aged sheep than estimates of previous authors.

1. Forty-five Large White gilts were given 2·20 kg daily of a diet containing 14·0% crude protein during three successive pregnancies. During a 6-week lactation they received 5·30 kg daily of one of three diets containing 19·0% (HP), 16·5% (MP) or 14·0% (LP) crude protein.

2. Daily milk yield was estimated on the 10th, 20th, 30th and 40th day of lactation. Milk samples were obtained from the same sows for the determination of protein, fat, lactose and total solids on the 11th, 21st, 31st and 41st day.

3. One sow and litter from each treatment in each lactation was placed in metabolism cages during lactation and estimates of nitrogen and dry matter excretion obtained.

4. As the concentration of protein in the diet decreased the average 42-day gain in litter weight from birth increased significantly in the first lactation. This trend continued in the second lactation although it was not significant but did not appear in the third.

5. There was no marked difference in daily milk yield between treatment groups.

6. There was a significantly greater loss of live weight by the sows on the lower levels of protein in the first lactation. These differences were not significant in the second and third lactations.