The aim of this work was to study the effect of the contemporary administration, in separate troughs, of two diets differing in digestible energy (DE) and crude fibre (CF) content, on the performance of lactating rabbit does. At the first mating (130 days of age and 3·8 kg), 54 nulliparous rabbit does (New Zealand) were assigned to the control group offered a conventional lactation diet (diet C: 188 g crude protein (CP) per kg dry matter (DM) and 11·43 MJ DE per kg DM); whilst another 54 rabbit does were offered at the same time, in separate troughs, diet E (203 g CP per kg DM and 12·66 MJ DE per kg DM) and diet F (178 g CP per kg DM and 10·73 MJ DE per kg DM). The contemporary administration of two diets did not significantly affect food intake. However, the rabbit does in group F + E, due to the greater consumption of diet E (approx. 0·76 of the total), consumed more digestible protein (DP) both during the first (14·40 v. 13·44 g/day per kg M0·75 and 80·1 v. 73·5 g/day per kg M0·75, respectively for days 1 to 21 and days 22 to 35) and subsequent lactations (15·37 v. 14·35 g/day per kg M0·75 and 82·6 v. 76·5 g/day per kg M0·75 respectively for days 1 to 21 and days 22 to 35). Also the DE intake was higher for the rabbit does of group F + E during the 22- to 35-day period (6708 v. 6361 kJ/day and 6918 v. 6620 kJ/day respectively for primiparous and multiparous). The improved performance of rabbit does given two different diets does not justify the extra time involved in such a technique, as the intake of diet E was constant during the experimental period and was not influenced by the different energy requirements during lactation.

This study investigated the factors affecting milk production and lactation curve parameters from the complete lactations of Awassi dairy sheep. The animals were kept in a single flock under intensive management and milked twice daily starting at lambing. Lambs were removed from the ewes at birth into an artificial rearing unit. The results of the analyses of 3740 complete lactations showed a mean litter size of 1·28 lambs born per ewe lambing and average total milk yield of 506 l from lactations 214 days in length and with an average lambing interval of 330 days. Mean lactation number was 3·71 and ewes conceived on average in the 6th month of the lactation. The lactations peaked on day 45 at a yield of 3·44 l. The maximum milk secretion potential of the ewes was 3·9 l/day, with milk yield increasing at 62 g/day mid way between lambing and peak yield and declining at 16·5 g/day mid way between peak and the end of lactation. Age at first lambing, lactation number, litter size, month of lambing and month of conception during the lactation had significant effects (P < 0·05) on some or all of the lactation parameters investigated. Relatively high milk yield was obtained in lactations starting in the January to March period. The monthly effect on milk production was explained by significant (P < 0·05) heat load and photoperiod effects. High milk production was found to have a significant (P < 0·05) adverse effect on reproductive performance. Conception followed a significant (P < 0·05) short term variation in milk production.

In ruminants and humans, the majority of whole body glucose utilization is not mediated by insulin. However, while in man most non-insulin-mediated glucose utilization (NIMGU) occurs in the brain, in ruminants the locations of NIMGU remain less well defined. As fasting would be expected to limit NIMGU to what would be regarded as an essential minimum, two studies were performed to establish the contribution of NIMGU to total glucose metabolism in fed and fasted sheep. Each study used four adult castrated male sheep. In study 1, a primed continuous infusion of U- [13C] glucose was begun at time 0 and continued for 7 h. After 3 h of isotope infusion (basal period) somatostatin (0•417 µg/kg per min; SS) was administered for 4 h, either alone (SS-only) or together with insulin (1•0 mU/kg per min; SS + insulin) with normal glucose to maintain euglycaemia for 2 h. Normal glucose was then infused for both the SS-only and SS + insulin treatments to induce and maintain hyperglycaemia over the final 2 h of the experiment. In study 2, fed or 72-h fasted sheep were infused with 6-[3H] glucose from time 0 for 8 h, with SS infusion starting at 3 h and continuing for 5 h. After 3 h of SS infusion, glucose was infused to induce and maintain hyperglycaemia. In both studies SS infusion inhibited insulin secretion, however in study 2, SS in fed sheep caused hyperglycaemia; this effect was not significant in the fasted animals. The rate of glucose utilization was reduced by SS-only as it eliminated insulin mediated glucose uptake (IMGU); under such conditions whole body glucose disposal should be NIMGU. In fed sheep, average NIMGU levels represented between proportionately 0•61 and 0•67 of the basal glucose metabolic clearance rate. During the infusion of SS + insulin in fed sheep, NIMGU fell to 0•34 during euglycaemia and 0•33 during hyperglycaemia, as the infused insulin caused IMGU to predominate. In fasted sheep the absolute rates of both IMGU and NIMGU were reduced, though NIMGU as a proportion of total turn-over (IMGU + NIMGU) increased to 0•88 of glucose metabolic clearance. Calculations suggest that, in contrast to man, only a minor proportion of NIMGU is utilized by the brain and central nervous system in fed or fasted sheep. It is suggested that skeletal muscle and the gastro-intestinal tract may make a major contribution to NIMGU, even in fasted sheep.

An experiment was carried out to study the effect of adding α-galactosidase to the diet on the performance and digestive parameters of growing-finishing pigs. Fifty-four gilts, average body weight (BW) of 43 (s.e. 0·4) kg, were allocated to 18 pens and used in a production experiment divided in two consecutive periods of 28 days each (growing and finishing). In each period gilts were given a diet based on cereals, soya-bean meal and peas, supplemented (Enzyme) or unsupplemented (Control) with 200 units per kg of α-galactosidase. All diets included 2 g Cr2O3 per kg as a digestibility marker. Food intake and body weight were recorded every 2 weeks and faecal samples by pen were collected at the end of each period. Average daily gain (ADG), food: gain ratio and faecal digestibility of dry matter (DM), crude protein (CP) and neutral-detergent fibre (NDF) were calculated. At the end of the production experiment nine gilts from each treatment were selected and given the finishing diet for a further 10 days before being slaughtered. Samples of digesta from the ileum and caecum were collected and ileal digestibility of monosaccharides determined. Short chain volatile fatty acids (SCVFA ) and purine bases (PB) in caecal digesta were analysed. The use of α-galactosidase improved the ADG (P < 0·01) and the food: gain ratio (P < 0·01) simultaneous to increases in the faecal digestibility of DM (P < 0·05), CP (P < 0·05) and NDF (P = 0·07) in the finishing period. Alpha-galactosidase supplementation also improved the ileal digestibility of some monosaccharides (galactose, rhamnose, mannose and fucose) of the dietary fibre fraction (P < 0·05); and reduced total caecal concentration of SCVFA (P = 0·15), proportion of branched-chain VFA (P < 0·001), and concentration of total PB (P < 0·001). It is concluded that adding α-galactosidase to a cereal-soya-bean meal-pea diet improves ADG, food: gain ratio and digestibility in fattening pigs, and reduces the amount of fermentable substrate flowing to the large intestine.

Fifteen sexually mature rams, five each of Barki, Awassi (I, imported from Syria) and Awassi (LB, locally born in Egypt) were used in this study. Semen was collected monthly from rams for a period of 12 months to study semen characteristics. In addition, blood samples were collected from rams during the four seasons of the year to determine serum triiodothyronine (T3) and testosterone hormones. Results showed that Barki and Awassi (I and LB) rams are continuous breeders as they show sexual desire and produce semen all the year round. However, monthly variations in semen quality were detected. Relative testes volume, ejaculate volume, sperm concentration, total sperm output, sperm motility, percentage of live sperm and serum testosterone level were higher during summer months than at other months of the year. Serum T3 was significantly higher in winter and spring than that observed in summer and autumn. In addition, percentages of dead spermatozoa were higher in winter and early spring than in autumn and summer. Furthermore, summer months showed moderate percentages of abnormal spermatozoa and spermatozoa without intact acrosomes. These results indicate that ram semen quality in the subtropics may be better during summer months than during other months of the year.

The intakes and in vivo apparent digestibilities (AD) of four forages: hay (H), haylage (HY), big-bale silage (BB) and clamp silage (CS), were investigated in Welsh cross pony geldings (live weight (LW) ca. 330 kg). The trial was a 4 ✕ 4 Latin-square design with diets offered at 1•65 g/kg dry matter (DM) per100 kg LW per day, in two equal meals. Food and faecal samples were analysed for DM, organic matter, crude protein (CP), gross energy, calcium (Ca), phosphorus (P), magnesium (Mg) and non-starch polysaccharide (NSP) composition and content. Significant differences (P < 0·05) in DM intakes (DMI) g/kg M0·75 were recorded between foods, where HY = BB = H > CS. For all measurements AD was significantly (P < 0·05) higher for BB and CS than for H, with HY being intermediate in all but digestibilities of Ca and Mg. Digestibility of NSP of BB and CS were significantly (P < 0·05) greater than for H and HY. The digestible energy (DE) of H, HY, BB and CS were 5·75, 9·09, 9·83 and 11·98 MJ/kg DM respectively, which coupled with the corresponding DMI resulted in all foods but H meeting the theoretical daily DE requirements of the ponies. Similarly, theoretical digestible CP requirements were met on all diets except H. NSP fractions accounted for 0·5 of daily DE in both H and BB, which were significantly (P < 0·05) higher than for CS and HY at 0·4 and 0·2 respectively. These results indicate that CS, BB and HY are readily digested by ponies and thus offer suitable high-energy alternatives to hay in horse rations.

A study was carried out in the dry season, from October 1993 to May 1994 at an institutional farm in Niono (14º5’N, 6ºE, 295 m), on the Sahelian border of Mali with a semi-arid climate. Thirty-four local Sahelian goats in their first to fifth lactation weighing about 27 kg were used. Eleven of them suckled twin and 23 suckled single kids. The does were herded on natural rangeland for 8 to 9 h/day and received no food supplements. Dry season forage mass, intake and nutritive value of diets selected by goats, milk yield and effects on kids’ growth were measured.

The vegetation cover consisted of a herbaceous stratum dominated by annual gramineae plants and a woody stratum composed of 26 species of plants, whose relative abundance varied according to the topography and soil type. The goats spent between 0·126 (early dry season) and 0·004 (late dry season) of grazing time on herbaceous cover and the remaining time on consuming leaves, flowers and fruits of woody plants. The phytomass decreased as the dry season advanced. However, nutrient intake was relatively constant during the course of the study period, as the goats compensated for low biomass by walking more and grazing larger areas and for longer periods. On average, goats selected diets with 121 g crude protein and 7·6 MJ metabolizable energy per kg dry matter.

The milk yield and milk fat were measured weekly for 29 weeks but data for only 12 weeks are interpreted and discussed. Mean daily actual and fat-corrected milk (40 g fat per kg milk) production for the first 12 weeks of lactation was 692 (s.e. 139) g and 627 (s.e. 73) g respectively. The milk yield was maximum in the 1st week of lactation followed by a gradual decline. Milk yield was affected by litter size, number of lactation, weight and age of does at parturition. The does with twin kids produced significantly more milk (762 (s.e. 110) g/day) than the does with singles (656 (s.e. 158) g/day) (P < 0·05). The milk yield increased from the first lactation (542 (s.e. 49) g/day) to the third lactation (739 (s.e. 49) g/day) (P < 0·05) with no difference between the third and fifth lactation. Does over 27 kg produced more milk than those under 27 kg (P < 0·001) and does over 2·5 years produced more milk than younger does (P < 0·01). Milk fat was inversely related to milk production. Kids born as singles were heavier (2194 (s.e. 76) g) than those born as twins (1966 (s.e. 78) g) (P < 0·05). The kid growth rate was affected by birth weight (P < 0·001) and milk yield of dams (P < 0·01). Within litter size (single or twins), sex had no significant effect on the growth rate of kids, however the singles grew faster than twins (P < 0·001) throughout the 12 weeks of measurement. Single kids were 1·41 times as heavy as twins at 12 weeks.

It is concluded that, the milk yield of does and weight gain of kids under the precarious feeding conditions of the study indicate that the local goats monitored were adapted to local harsh conditions. Nutrition has been regarded as the main constraint to goat production from the range in the dry season. Further specific studies are needed to overcome the dry season nutritional stress and to improve goat production.

Fifteen sexually mature rams, five each of Barki, Awassi (I, imported from Syria) and Awassi (LB, locally born in Egypt) were used to study the biochemical and enzymatic properties of seminal plasma for 12 months. The biochemical analyses of ram seminal plasma indicated that the highest values of total protein, albumin (A), globulin (G), fructose, total lipids and cholesterol were recorded in late summer and early autumn, while A/G and AST/ALT ratios exhibited the lowest values. Lowest values of the same parameters were recorded in winter and late spring, while ratios of A/G and aspartate amino transferase (AST)/alanine amino transferase (ALT) showed the highest values in spring. AST enzyme activity showed highest activity in winter and summer and lowest activity in autumn, while ALT exhibited the highest activity in winter and the lowest activity in spring. The relationships between these parameters and semen quality are discussed.

The conventional system of estimating metabolizable protein requirement is unsuitable for defining amino acid requirements because nitrogen loss cannot be converted to amino acid loss, and because there is a lack of data on the utilization efficiencies of individual amino acids for various productive purposes. Therefore, we are proposing an alternative approach. In this review, we use methionine (Met) and cysteine (Cys) for wool production in sheep as examples, and define requirement as retention in both body and wool protein, plus the amount of obligatory oxidation that accompanies the retention. The requirements are expressed in terms of the net absorption. Mathematical models for the calculation of the requirements of both amino acids are established based on the level of absorption, endogenous contribution from body protein breakdown, oxidation rates and the amino acid composition of body and wool proteins. The flows and oxidation of Met and Cys, and Cys synthesis de novo as well are quantified using their plasma kinetics data. Wool growth rate is predicted from the amount of the amino acid available for protein retention and the partition ratio to wool growth. The estimated requirements for Met and Cys absorption for Merino sheep at maintenance are 0·45 to 0·75 g/day and 0·52 to 0·63 g/day depending on the live weight of the sheep. When wool growth rate increases to 10 g/day, the requirements increase to 0·91 to 1·24 g/day and 1·97 to 2·02 g/day respectively. The utilization efficiency for protein retention varies with the level of absorption, and is 0·02 to 0·55 for Met, and 0·09 to 0·55 for Cys. The model shows that wool growth rate is restricted by the lack of Cys supplied in conventional diets and is very sensitive to changes in oxidation of the amino acids.

This study investigated the effects of dietary n-3 polyunsaturated fatty acids (PUFA) on muscle fatty acid composition and content in two cattle breeds; the Holstein-Friesian, a dairy breed, and the Welsh Black, a traditional beef breed. Animals were kept on ad libitum grass silage and one of three concentrates varying in the source of fat; Megalac (high in C16 : 0), formaldehyde treated whole linseed (high in C18 : 3 n-3) and a combination of formaldehyde treated whole linseed and fish oil (high in C20 : 5 n-3 and C22 : 6 n-3). The concentrates were offered at approximately 0·4 of total dry matter intake. Samples of m. longissimus thoracis from Holstein-Friesians contained higher total amounts of fatty acids (P < 0·05) than that of Welsh Blacks in neutral lipid, but the phospholipid fatty acid content was similar between the breeds. Over all treatments, the proportion of C18 : 3 n-3 was higher (P < 0·001) in muscle neutral lipid of Welsh Blacks and the proportions of C18 : 3 n-3 and C18 : 1 trans were higher (P < 0·05 and P < 0·001, respectively) in their subcutaneous adipose tissue. Feeding linseed increased the amounts of C18 : 3 n-3 and also C20 : 5 n-3 in muscle phospholipids suggesting chain elongation and desaturation of C18 : 3 n-3 had occurred. The concentration of C20 : 5 n-3 was significantly higher (P < 0·05) in muscle phospholipids of Welsh Blacks while no differences were found for C18 : 3 n-3 and C22 : 6 n–3. However, when expressed as a proportion of total fatty acids, both C20 : 5 n-3 and C18 : 3 n-3 were significantly higher (P < 0·001) in the Welsh Black phospholipids. These differences resulted in a significantly higher P : S ratio of the muscle total fat (P < 0·05) in the Welsh Black than in the Holstein-Friesian but P : S was not affected by diet. On the other hand, the n-6 : n-3 PUFA ratio was significantly lower in the Welsh Black, reflecting the higher n-3 PUFA content. This ratio was lower in the linseed and the mixed treatments for both breeds, reflecting higher delivery of n-3 PUFA from these diets. Fortification of the diet with sources of PUFA and exploiting breed differences offer the potential to develop systems to increase human intakes of n-3 PUFA in line with current nutritional recommendations.

Sixty-four Azawak male calves were used to study the effect of nocturnal grazing (NG) and supplementation (S) in the dry season on forage and water intake, faecal output, eating time and weight changes of cattle in the Sahel. Treatments were factorial combinations of four levels of NG (0, 2, 4 and 6 h/day) and two levels of S (0 and 608 g dry matter (DM) per animal per day). All animals were allowed to graze 10 h during the day and were weighed every 2 weeks during the 70-day experimental period. Eight oesophageally fistulated steers were used in a cross-over design to sample the diet (forage) selected during the day and at night by supplemented and non-supplemented animals. Extrusa crude protein and in vitro organic matter digestibility were not influenced by supplementation (P > 0·05). Time spent eating during the day or at night were not affected by supplementation but total eating time increased by 39·4 (s.e. 2·1) min/h of NG. Forage intake increased with increase in NG, while total food intake (forage + supplement) increased with supplementation (82·4 v. 92·1 (s.e. 2·4) g DM per kg M0·75 per day). The supplemented animals also drank more water than the non-supplemented (26·2 v. 24·8 l per animal per day). Average live-weight change (LWC) increased by 24·4 (s.e. 8·7) and 9·3 (s.e. 6·2) g/h of NG in non-supplemented and supplemented animals, respectively. Supplementation improved LWC (–107 v. 99 g/day, s.e. 14, P < 0·05). Night grazing improves dry season performance and its effect decreases when cattle are supplemented.

Twenty-four multiparous ewes were used to test the hypothesis that synchronizing the hourly rate of release of energy and nitrogen in the rumen would optimize milk production. Three diets were formulated using the in situ degradability of the food ingredients, to differ in their rate of organic matter (OM) and nitrogen (N) release in the rumen. All diets contained 400 g grass silage per kg dry matter (DM) and were predicted to have a similar content of metabolizable energy (11·8 MJ/kg DM), metabolizable protein (102 g/kg DM), neutral-detergent fibre (365 g/kg DM) and daily ratio of N: OM supply to the rumen but differ in their hourly pattern of nutrient release to be either synchronous (S), asynchronous (A) or intermediate (I). The diets were offered ad libitum as a complete feed in a 3 × 3 Latin-square design consisting of three periods each of 28 days duration. Synchronizing the hourly supply of energy and N to the rumen did not significantly alter milk or milk fat yield (g/d), milk protein content (g/kg), DM intake (kg/day), total time spent eating or the number of meals per day. However, compared with ewes offered diets I or A, those offered diet S had a lower milk fat content (g/kg; P < 0·05) whilst protein yield (g/day) tended to be increased (P = 0·05). Animals offered the synchronous diet (S) had lower plasma urea concentrations throughout the day and significantly higher beta-hydroxybutyrate concentrations at 14:00 and 18:00 h than those offered diets I or A. In conclusion, synchronizing dietary energy and N supply to the rumen did not have a major effect on milk production in ewes.

Switchgrass (Panicum virgatum cv. Alamo) standing hay was cut and offered to 16 rams. The rams were randomly allocated to one of the following levels of feeding: 0·5; 1·0; 1·5 and 2·0 ✕ maintenance. The forage was offered twice a day to the animals; no supplements were given. The animals were individually penned and fitted with faeces collection bags. After 8 days for adaptation, in vivo dry matter apparent digestibility (DMD) and proportion of blades and stem + sheath of the consumed forage were measured for 8 days. DMD varied from 0·310 (0·5) to 0·391 (2·0) and the proportion of the blade fraction in the diet from 0·44 (0·5) to 0·78 (2·0). The short-term intake rate (STIR) of rams was measured for 5 days. The animals were divided randomly into four blocks, with one ram of each treatment in each block. After 4 h without food and 15 min intervals between blocks, the amount of forage consumed during 4 min of active eating was measured. The amounts consumed were (in g DM per min per 50 kg live weight): 0·5: 8·2; 1·0: 7·8; 1·5: 5·3 and 2·0: 5·3 (0·5 = 1·0 > 1·5 = 2·0; P < 0·01). The results show that offer rate of P. virgatum affects the blade: stem + sheath ratio of intake and, therefore, the nutritive value of the diet. Level of feeding before measuring STIR influences the amount of forage consumed during the test.

The main objective of the experiment was to investigate the conditioned responses of sheep towards food flavours associated with the administration of ruminally degradable protein (RDP) and ruminally undegradable, but readily digestible protein (DUP) sources given either alone or in combination. The experiment consisted of three consecutive periods during which sheep were conditioned to associate a flavoured food with a nutritive stimulus (or water, W). Two foods (basal and novel test) with different crude protein (CP; 92 and 64 g/kg dry matter (DM) respectively) and similar metabolizable energy (≊ 9 MJ/kg DM) contents were used on a total of 48 Texel ✕ Greyface female sheep. The basal food was offered during non-experimental (rest) days whereas the test food was used in combination with two flavours, orange and aniseed, during experimental days. Food was presented for 8 h (09:00 to 17:00 h) daily throughout the experiment. Two nutritive stimuli (casein, C, and formaldehyde treated casein, FC) were chosen such as to provide major contrasts in their RDP and DUP contents, on an isonitrogenous basis. Each dose (50 g) of a particular nutritive stimulus was administered by gavage through a stomach tube twice daily (at 10:00 and 14:00 h). Sheep were randomly assigned to one of four (C v . W, FC v . W , C v . FC, C v . FC + C) treatments (no. = 12 per treatment). For the first 2 days (days 1 + 2) of each conditioning period half of the sheep within each treatment were offered one flavoured food paired with the administration of C (treatments C v . W , C v . FC and C v. FC + C) or FC (treatment FC v. W). The other half were offered the opposite flavoured food paired with the administration of water (treatments C v . W and FC v . W), FC (treatment C v . FC) or C + FC (treatment C v . FC + C). There followed 2 days (days 3 + 4) of rest and for the 2 days subsequently (days 5 and 6) received the opposite flavoured food and the opposite stimuli to that received earlier. In the morning of day 7 sheep were offered a choice between the two flavoured foods for 20 min. After the completion of the preference test sheep were offered the basal food. The same procedure was followed for each of three conditioning periods (i.e. each animal followed the same flavour/stimulus association throughout the experiment). The design was balanced for order of flavour and stimulus presentation. Sheep preferred the flavoured food associated with C (P < 0·05) or FC (P < 0·01) over the opposite flavoured food associated with water in C v . W and FC v . W treatments respectively. In the C v . FC treatment sheep showed a strong preference for food flavours associated with the administration of FC to those associated with C (P < 0·05). In the C v. FC + C treatment sheep showed equal preference towards the food flavours associated with either stimuli. These results: (i) support the view that sheep are able to form learned preferences for food flavours associated with the administration of protein, and (ii) suggest that sheep are able to distinguish between food flavours associated with the administration of both RDP and DUP sources. Sheep preferred flavours associated with DUP administration only over flavours associated with RDP administration only; however, such preferences did not develop when DUP was administered concurrently with RDP. Given the learned responses of sheep towards flavours associated with RDP and DUP the expectation is that they may be able to select their diet on the basis of these qualities when they are offered a choice.

Twelve dairy cows in early lactation were offered low (L; 215 g/kg) or high (H; 449 g/kg) dry matter(DM) content silages, prepared using material from the same sward. In addition, all animals received 9 kg/day, of supplements based on barley (B), sugar-beet pulp (SB) or a 50: 50 mixture of the two (B: SB), in two equal portions at 07:30 and 14:30 h. The six treatments were offered in an incomplete Latin square design. Mean intakes of H (14·4 kg DM per day) were significantly higher than intakes observed for L (10·0 kg DM per day) (P < 0·001). Within silage type, highest intakes were observed for cows receiving the SB supplement (P < 0·01). Higher intakes of H were reflected in higher total milk yield (P < 0·05) as well as fat (P < 0·05) and protein (P < 0·01) yield. Milk protein concentration was greater for animals receiving silage H (P < 0·001), with lower values being observed for animals consuming SB (P < 0·05), within silage type. Time spent eating, duration and number of meals were similar for either silage and the higher intakes of H silage reflected greater intake rates (g DM per min) (P < 0·001) resulting in larger meal sizes (P < 0·001). All chewing indices (time spent eating silage, ruminating and total time chewing per kg DM ingested) were greater for the L silage (P < 0·001). It is concluded that the benefits in forage intake with higher DM grass silages, for high yielding dairy cows, are associated with consequential benefits in milk yield and milk protein content. The most likely explanation for the greater intakes is a faster particle breakdown in the rumen allowing larger meal sizes before animals became constrained. The higher intakes of silage when animals consumed the SB supplement may be due to a slower rate of fermentation of the supplement, which was more closely matched to that of silage. Although not significant there was a tendency for differences in silage intake between animals receiving B compared with SB supplements to be greater for animals receiving the H silage suggesting that supplementation strategies to ensure optimal forage utilization may differ for silages of differing DM content.

A preliminary study was conducted to quantify the lipid produced by differentiated 3T3-L1 cells after incubation in Dulbecco’s Modified Eagle Medium (DMEM) containing 10% foetal bovine serum (FBS), supplemented with or without dimethyl-sulphoxide (DMSO; 9•6 g/l) and acetone (1•2 g/l). The two media treatments were applied to 3T3-L1 cells, plated at either 15K or 30K cells per well in 24-well plates. Cells were grown to confluence (96 h) and then treated with dexamethasone, methyl-isobutylxanthine and insulin for 48 h and later maintained in their respective media treatments for another 144 h. Cells from each treatment were recovered after two, 5-min incubations with trypsin, washed and resuspended in DMEM and counted on a haemocytometer. The lipid in the cells was extracted with hexane derivatized with tetramethyl-guanidine and analysed by gas chromatography. Final mean cell density was 6•8 (s.e. 0•18) ✕ 105 and 4•6 (s.e. 0•19) ✕ 105 when initially plated at 30K and 15K cells per well, respectively. Inclusion of DMSO and acetone in the medium did not affect final cell numbers. Plating density did not affect concentration of lipid (0•55 (s.e. 0•08) mg per 1 ✕ 105 cells) but inclusion of DMSO and acetone led to overall decreases in total lipid concentration. Results indicate that initial plating density influenced final cell number in treatment cultures, but that DMSO and acetone treatments only had an effect on final lipid concentration. Collectively, these data suggest that the application of treatments to cell cultures may be influenced by the carrier vehicle that the treatment is contained in and this should be considered when developing an in vitro system to evaluate growth and development of adipocytes.

In a 12-week trial, 12 Alpine and 12 Saanen dairy goats in mid lactation were housed in individual stalls for behavioural, digestive and metabolic studies. Eight of them were fitted with ruminal cannulae. They were offered ad libitum four complete diets CR, CS, FR and FS (450 g dry matter (DM) per kg) in a 4 ✕ 4 Latin-square design. Forage: concentrate ratio was either low (C = 30: 70) or high (F = 55: 45) and starch source either rapidly (R, barley) or slowly (S, maize) degraded in the rumen.

Diet preferences were tested. DM intake, chewing activities and performance were determined. Ruminal pH and ammonia-nitrogen (NH3-N) concentrations were measured. Goats were also challenged intravenously with glucose (0·2 g/kg live weight) to assess glucose homeostasis.

CR was the most preferred diet. The level of intake differed according to the type of starch (2·2 kg DM per day of CR and FR and 2·0 kg DM per day of CS and FS). FS lowered ruminal pH significantly less than the other diets after the meal. Ruminal NH3-N concentrations were lower in goats given CR and CS than FR and FS. Goats’ resistance to a glucose challenge was not different among diets. Milk yield was 2·00, 1·85, 2·01, 1·85 kg/day on CR, CS, FR and FS respectively. Milk fat content decreased significantly with diets rich in concentrate (24 v. 26 g/kg milk) but milk protein content varied only a little.

In conclusion it appears that (1) higher forage: concentrate ratios were less preferred and decreased ruminal acidity but increased daily chewing, ruminal NH3-N and milk fat content; and (2) rapidly degraded starch increased intake, ruminal acidity and milk yield.

The purpose of this study was to estimate the heritabilities and the genetic correlations of osteochondrosis in different joints and to estimate genetic correlations between osteochondrosis, leg weakness and production traits. The humerus condyles, anconeal process, distal ulna growth line, femoral condyles, distal tibia and medial trochlear ridge of talus on both sides of the animals were examined radiologically for osteochondral lesions and scored from 1 to 5 with increasing severity. The boars were also scored for 13 different leg weakness traits on a scale from 1 (normal) to 5 (very severe changes). During a 3-year period, a total of 2042 Landrace boars from 256 sires and 1946 Yorkshire boars from 240 sires were examined at a mean weight of 93 kg. The data were analysed by animal models for each breed. The Landrace was found to be more severely affected than the Yorkshire regarding osteochondrosis in all localities expect the anconeal process. The genetic correlations between left and right side scores of the osteochondral trait were close to 1. This indicates that genetically the same trait is measured in the left and in the right side of the animal. The heritability of average osteochondrosis scores was low to moderate ranging from 0•08 to 0•39 (s.e. between 0•02 and 0•04). The genetic correlations between osteochondrosis in the different body localities were low, indicating that osteochondrosis is not a generalized disease. The Landrace was more severely affected than the Yorkshire regarding all leg weakness symptoms except buck-kneed forelegs, forelegs turned out and weak pasterns on forelegs. The heritability of leg weakness traits ranged from 0•01 to 0•35 (s.e. between 0•01 and 0•04). Genetic correlations between osteochondrosis and leg weakness showed a clear picture for the Yorkshire breed regarding the humeral condyles: positive correlations with buck-kneed forelegs, forelegs turned out, stiff in front and rear. In both breeds osteochondrosis in femoral condyles showed a high positive correlation with hind legs turned out and a lower positive correlation with stiff in front. The sum of osteochondrosis traits (sumost) was unfavourably genetically correlated with daily gain, whereas the sum of leg weakness traits (sumleg) was unfavourably correlated with lean meat percentage in both breeds. The correlation between the summary measures sumost and sumleg was 0•09 (s.e. 0•11) in the Landrace and –0•07 (s.e. 0•12) in the Yorkshire.