The plasma concentrations of glucose, insulin, lactate, cortisol and free fatty acids were investigated in normal pigs and those with the homozygous and heterozygous genetic mutation for malignant hyperthermia (MH). Blood samples were obtained during a 24-h resting period, a glucose tolerance test and during a treadmill test with submaximal physical load conditions. The homozygous MH positive animals elicited the highest glucose concentrations and the homozygous MH negative animals the lowest at each sampling time during the 24-h period (P < 0·01). During the glucose tolerance test, the most pronounced post-prandial increase and the highest plasma concentrations of glucose were found for the homozygous MH positive animals (P < 0·01), which was associated with a late release of insulin. Increasing work loads during the treadmill test run resulted in an increase of plasma cortisol concentrations in all animals (P < 0·01), with the more pronounced increase for the homozygous and heterozygous MH positive animals. Plasma free fatty acid concentrations during the treadmill test differed between the genotypes (P < 0·05). A pronounced increase was found for the homozygous and heterozygous MH positive animals, whereas the MH negative animals provided very constant free fatty acid values, at a low level, independent of the work load. These results indicate that the genetic mutation for MH in pigs affects the metabolic pathways of the energy metabolism, resulting in higher plasma glucose concentrations at rest and higher lipolytic activities under physical load conditions.

An experiment involving 18 individually fed barrows weighing about 81 kg was conducted to determine the effects of a high ambient temperature (30°C v. 22°C) and dietary fat supplementation (100 g/kg diet of encapsulated-tallow v. 0 g/kg) on growth performance and carcass fatness of finishing pigs. Digestible energy (DE) intake and growth rates were significantly lower at a high ambient temperature (P < 0·001). Dietary fat supplementation considerably increased DE intakes at a high ambient temperature (40·0 v. 33·8 MJ/day) while slightly increasing it at a thermoneutral temperature (53·1 v. 50·6 MJ/day). Dietary fat supplementation tended to increase growth rates and significantly improved the efficiency of food utilization (P<0·01). Pigs with dietary fat supplementation exhibited greater enhancement in backfat depths, carcass fatness and internal organ fat at a high ambient temperature than at a thermoneutral temperature. Linear correlation between DE intake and crude fat concentration of carcasses was statistically significant at a high ambient temperature (P < 0·01, r = 0·71). Although there appeared to be a positive correlation, it was not statistically significant at a thermoneutral temperature (P > 0·05). Crude fat concentration of the internal organs linearly correlated with DE intake (P < 0·01, r = 0·66). However, fat concentration of the internal organs did not correlate to DE intake at a thermoneutral temperature. The present study indicated that although dietary fat supplementation improved growth performance of pigs over 81 kg live weight initially in hot environments, there was the disadvantage of excessive fat deposition in their bodies.

Semen collection from three boars was performed twice a week, and doses (100 ml each) of semen diluted with Beltsville Thaw Solution (BTS) extender were prepared containing 1 × 109, 3 × 109 and 5 × 109 spermatozoa. Diluted semen was then stored at 17°C for a maximum of 120 h. Percentage of motile spermatozoa (PMS) and type of spermatozoa motility (TSM) were determined by microscopic examinations performed at 24-h intervals, from zero time (beginning of storage at 17°C) up to 120 h of storage, and a sperm motility index (SMI) calculated. Sows (no. = 360) were divided into nine experimental groups (40 sows per group) and a combination of number of spermatozoa per dose and storage time was used for artificial insemination in each group. All the animals were inseminated twice at 12 and 36 h after detection of standing oestrus by a teaser boar. Return and farrowing data including litter size were recorded. PMS, TSM and SMI decreased significantly (P < 0·01) from 48 h up to 120 h of storage, this being more marked in semen doses of 5 × 109 spermatozoa. When semen stored for up to 24 h was used, no significant differences (P > 0·05) regarding return rates and farrowing rates were observed among the three groups inseminated with semen containing different numbers of spermatozoa per dose. Inseminations with semen doses of 1 × 109 and 3 × 109 spermatozoa stored for 48 to 72 h have significantly lower return rates (P < 0·05) and significantly higher farrowing rates (P < 0·05) than with doses of 5 × 109 spermatozoa. Inseminations with semen stored for more than 72 h gave relatively higher return rates and lower farrowing rates. Semen storage time and number of spermatozoa per dose appeared to reduce litter size only where semen doses of 5 X109 spermatozoa were inseminated after storage for more than 48 h.

Red deer calves were reared from birth to 16 months in either constant intermediate 12L: 12D daylength (ID) or in natural photoperiod (NP) (four males and four females per group) to investigate effects on the somatotropic and reproductive axes, and to compare responses between the seres. Measurements, starting from 3 months (September), were made each week of live weight (LW), voluntary food intake (VFI), plasma prolactin, plasma insulin-like growth factor-1 (IGF-1), and plasma progesterone (females), and every 2 months of pulsatile LH secretion, plasma testosterone (males), responses to exogenous GnRH, and antler development (males).

Both sexes in ID compared with NP had significantly higher LW gain (males, P < 0·001; females, P < 0·01) and VFI (P < 0·001) between winter solstice (WS) and spring equinox (SE), and VFI between SE and summer solstice (SS) (males, P < 0·05; females P < 0·01). Both sexes had significantly lower plasma prolactin concentrations in ID than in NP (males, P < 0·05; females, P < 0·01) between SE and SS. However, plasma IGF-1 was only significantly altered in males, being significantly higher in ID than NP between WS and SE (P<0·01). ID and NP females showed no significant differences in pulsatile LH secretion nor in the timing of pubertal ovulation. However, ID compared with NP males at 10 months (just after SE) had higher LH and testosterone pulse frequencies (P < 0·01), and at 12 months (just before SS) had higher mean testosterone concentrations (P < 0·01) and testosterone response to GnRH challenge (P<0·001). ID antlers hardened earlier at 11 months than NP antlers at 14 months (P < 0·001).

Thus ID compared with NP in both sexes prevented the winter reduction in growth and appetite and the summer elevation in prolactin secretion, and in males, but not in females, stimulated higher IGF-1 secretion in winter, an earlier increase in LH pulse frequency, and an earlier increase in gonadal steroid production. This study has therefore revealed some intriguing similarities and contrasts in the responses to photoperiod shown by young male and female deer.

The aim of this experiment was to study the effects of dietary energy level and source on foetal growth and survival and mobilization of body stores in concurrently pregnant and lactating primiparous rabbit does. Does were given a moderate-energy diet (≍9·9 MJ digestible energy (DE) per kg dry matter (DM); group M, no. = 23) or a high-energy diet (-12·2 MJ DE per kg DM). In this latter case, additional energy came from starch (group S, no. = 23) or starch and fat (group F, no. = 22). Primiparous rabbit does were mated within 12 h after parturition and were slaughtered on day 28 of gestation-lactation. During the first 21 days, the DE intake and milk production were higher in the group F than in the groups S and M (P < 0·05). On day 28 of pregnancy, the weight of adipose tissues and liver, as well as the lipid content of the carcass, were higher in the groups S and F than in the group M (P < 0·05). Foetal survival and weight were similar in the three groups. These results indicate that increased energy level of the diet did not improve foetal survival or growth in concurrently pregnant and lactating primiparous does. On the contrary, it could reduce the mobilization offat stores, especially if the energy source is starch.