Four groups of six cows were fed from 12 weeks before calving to achieve condition scores at calving of 3·15 (F) and 2·15 (T). For the first 20 weeks of lactation all cows were given 8 kg concentrate (13·93 MJ metabolizable energy (ME) per kg dry matter (DM), 200 g crude protein (CP) per kg DM) which contained either a high or a low dietary concentration of undegradable dietary protein (UDP) (70 g/kg DM, H, and 49 g/kg DM, L) and 3 kg sugar-beet pulp. Hay was also offered ad libitum.

There was no significant effect of treatment on milk yields over the first 20 weeks of lactation (overall mean yield 27·3 (s.e. 3·65) kg/day) but cows in group FL tended to produce less (P > 005). Milk composition was similar for all groups (48·8 (s.e. 5·12) g fat per kg, 27·2 (s.e. 1·48) g protein per kg and 49·0 (s.e. 2·52) g lactose per kg). DM intakes for groups FH, FL, TH and TL were 18·1, 16·9, 17·5 and 18·2 (s.e.d. 0·58) kg/day, respectively (TL v. FL, P < 0·05; FH v. FL, P < 0·05). Mean condition scores for groups FH, FL, TH and TL respectively, were 3·T7, 3·13, 2·21 and 2·08 (s.e.d. 0·18) at calving; 2·25, 2·50, 2·21 and 1·83 (s.e.d. 0·27) in week 10; and 2·46, 2·83, 2·46 and 1·96 (s.e.d. 0·35) in week 20, of lactation. Groups FH, FL, TH and TL lost proportionately 0·09, 0·02, 0·01 and 0·04 (s.e.d. 0·035) of their calving live weights, respectively, over 20 weeks of lactation.

It is concluded that increasing the supply of UDP to cows which are fat at calving results in a greater negative energy balance and a small though non-significant increase in mobilization of body fat reserves. At the dietary ME and protein concentrations used, the thin cows could not respond to increased UDP supply and their intake was limited by physical restriction.

The four sex phenotypes were used to study the relationship between carcass composition and serum profiles of hormones thought to affect growth. Forty calves (10 bulls, 10 steers, 10 heifers and 10 ovariectomized heifers) from Hereford dams crossed with Simmental-Hereford bulls (¾ Simmental-¼ Hereford) were given a high energy diet from 10 to 16 months of age. Sequential blood samples (20-min intervals) representing 6-h windows were obtained from each animal at the outset of the experiment and at 28-day intervals thereafter. Samples were assayed for growth hormone (GH), insulin, triiodothyronine, cortisol, testosterone, oestradiol-17β, urea and albumin. The 9-10-llth rib was dissected into fat, lean and bone, and chemical analysis was performed on the dissected soft tissue. Bulls accumulated more lean tissue and less fat than any other group. Heifers and ovariectomized heifers accumulated the least lean and most fat while steers were intermediate between bulls and the two heifer groups. Bulls may have accumulated more lean and less fat than the heifers due to higher GH and testosterone concentrations, and lower circulating concentrations of cortisol and insulin. The known function of these four hormones and their relative concentrations between bulls and the two female groups were consistent with their suggested role in the relative carcass compositions. The intermediate composition of the steer carcass may have resulted from an interplay between the proteogenic influence of higher GH concentrations, the proteolytic influence of elevated cortisol, the absence of testosterone and the lipogenic influence of higher insulin.

In three experiments, 16, 24 and 22, May-calving Aberdeen Angus × British Friesian cows were subjected either to single suckling of their natural calves or to single suckling in addition to ‘foster’ suckling for the first 8 to 9 weeks of lactation. Foster suckling was achieved by the removal of cows from pasture twice daily and suckling of male Friesian calves while cows were confined in a creep. Average milk yield per cow removed by foster suckling and milk secretion rates of individual cows were measured at intervals and cows were grazed at equal grazing pressure. Single plus foster suckling increased estimated total yield over single suckling proportionately by 0·55, 0·18 and 0·34 in the three experiments respectively. After foster calves were weaned, milk secretion rate of foster-suckling cows was always higher than that of naturally suckling cows. In addition to a mean yield of about 300 kg milk per cow to foster calves, single plus foster suckling increased calf gain in the natural calves in each experiment although the increases were not significant. The apparent conversion of extra milk consumed by natural calves in the single plus foster suckling treatment was generally low in relation to figures quoted in the literature.

Purebred cows were evaluated for reproductive performance and live weight, and for pre-weaning growth and viability of crossbred progeny sired by unrelated breeds. The cows comprised three indigenous breeds, Mashona, Nkone and Tuli and four exotic breeds Africander, Brahman, Sussex and Charolais. Over 3 years, the mean calving rates % (s.e.) were 55·5 (3·0), 76·0 (3·8), 63·1 (4·5), 69·6 (3·5), 70·0 (3·8), 60·0 (4·3) and 67·0 (5·0) for Africander, Mashona, Nkone, Tuli, Brahman, Sussex and Charolais cows, respectively. Bos taurus and Brahman cows were heavier at parturition and at calf weaning than indigenous cows. Mashona cows were lightest at both stages. Calves of Bos taurus cows were heaviest at birth and those of Mashona lightest. Calves of Brahman cows had the most rapid growth rate and at weaning (240 days) weighed in kg (s.e.) 207 (3·1), compared with 184 (2·1), 172 (2·2), 187 (2·6), 184 (2·1), 178 (2·7) and 186 (2·9) for progeny of Africander, Mashona, Nkone, Tuli, Sussex and Charolais, respectively. Pre-weaning survival rates of the breeds were not significantly different but viability was higher in progeny of indigenous than exotic breeds. The productivity estimates combining calving rate, cow weight, calf weaning weight and pre-weaning viability demonstrated the superiority of indigenous breeds and the Brahman over Africander and Bos taurus breeds.

Crossbred cows were evaluated for reproductive performance and live weight, and for pre-weaning growth and viability of progeny sired by seven unrelated breeds. They were also evaluated on overall productivity expressed as weight of weaned calf per cow mated per year, per 100 kg of cow per year and per 100 kg metabolic weight of cow per year. The cows comprised reciprocals of Africander with Mashona, Nkone, Brahman and Sussex, one-way crosses sired by Sussex out of Mashona, Nkone and Brahman dams, and by Charolais out of Africander, Mashona, Nkone, Brahman and Sussex dams. These represented sanga × sanga, sanga × zebu, Bos taurus × sanga, Bos taurus × zebu and Bos taurus × Bos taurus crossbred types. Bos taurus × zebu crosses were superior to other breed types for all the three productivity indices and for virtually all the individual components of these. There was little difference between the other four breed types in overall productivity of components of these. Differences between reciprocals were observed in sanga × sanga and sanga × zebu, cows with Africander dams being more productive than reciprocals with Mashona, Nkone and Brahman dams. The Bos taurus × Bos taurus cross was inferior in overall productivity primarily due to large cow weight and relatively low growth rate of progeny. Progeny sired by Friesian, Simmental and Brahman had higher weaning weights than those sired by Hereford, Aberdeen Angus, Africander and Tuli. Overall, heterosis was positive for all traits and averaged 0·15 for the three measures of cow productivity. Heterosis was three times higher in the Bos taurus × Bos indicus cross than in the Bos indicus crosses.

The effects of average carcass fat concentration of a group of lambs on correlations among lamb carcass measurements within the group and of slaughter age on variances of carcass measurements were studied. Three-hundred and sixty-eight crossbred lambs from one experiment were slaughtered on 10 days over a 2-year period. Average carcass fat concentration of the 10 groups ranged from 179 to 326 g/kg carcass weight. Variances of carcass fat, water and protein concentrations and of muscle measurements did not increase at later slaughter ages but variances of kidney fat weight, fat depths and total tissue depths increased. Several correlations among carcass measurements had significant regressions on average carcass fat composition of the groups slaughtered. When measurements were adjusted for age but not weight, correlations of carcass weight, kidney fat weight, specific gravity, tibia and tarsus length and m. longissimus depth with carcass fat, water and protein concentrations weakened as carcass fat concentration of the group increased. Correlations of kidney fat, specific gravity and m. longissimus width with fat, water and protein concentrations adjusted for carcass weight weakened as average carcass fat concentration of the group increased. Multiple regression equations did not reveal any advantage in using combinations of muscle or leg dimensions to predict fat concentration.

Fat depths of Southdown and Suffolk rams were ultrasonically measured several times prior to 18 months of age. Ultrasonic measurements were regressed on live weight and deviations from this regression were standardized and summed to select rams with high and low fat depth to produce crossbred progeny for slaughter. An average of 3·24 standard deviations separated high and low sires. Progeny were slaughtered at two ages to determine differences in carcass fatness and its development. A significant difference of 0·5 mm fat depth over the loin eye muscle was found between progeny of low and high sires. Progeny from Suffolk high sires had greater tissue depth over the rib and higher kidney fat weight than those from Suffolk low sires but differences were small or reversed in Southdown progeny. Low progeny had significantly less estimated carcass chemical fat than high progeny. Fat depth C increased less in low progeny between early and late slaughter ages. However, no difference in partition of carcass weight gain to fat weight gain was observed between high and low progeny. Differences in fat weight between high and low progeny, as well as between Southdown and Suffolk progeny, appeared to have occurred prior to the earlier slaughter age.

Straw from six varieties of oat and 12 varieties of wheat were divided into their botanical fractions of leaf plus leaf sheath, internodes, nodes and chaff, and the rumen degradabilities of the individual fractions determined by the nylon bag method.

The proportions of the fractions varied between varieties, but more so within wheat than within oat straw. The proportion of leaf plus leaf sheath varied from 0·27 to 0·37 for wheat and 0·29 to 0·33 for oats with the proportion of stem ranging from 0·41 to 0·51 for wheat and from 0·55 to 0·60 for oats. There were also differences in degradation characteristics, more evident in wheat than in oats. The 48-h degradability varied from 570 to 650 g/kg for wheat leaf plus leaf sheath and from 300 to 380 g/kg for wheat stem. The respective ranges for oat straws were from 480 to 530 and from 250 to 280.

Generally, the wheat straw varieties, and in particular leaf from wheat straw, were of a higher degradability than oat straw. The mean 48-h degradabilities of wheat and oat leaf were 615 and 501 g/kg respectively. There was no relationship between the nitrogen content of leaves or stems and their degradability.

Three diets containing 0, 45 or 90 g fish meal dry matter (DM) per kg diet DM were given to lambs in sufficient quantities to provide energy for maintenance and 150 g daily gain. The lambs grew directly from 30 to 40 kg live weight (C) or were given a maintenance diet only such that they remained at 30 kg live weight for 12 weeks before being allowed to proceed to 40 kg (R). The 48 lambs were slaughtered at 40 kg. Preliminary slaughter groups provided data upon the fleece-free empty body weights for both C and R lambs at 30 kg live weight.

There were no significant diet × growth pattern interactions. R lambs ate more DM (P < 0·01) and had greater fleece-free empty body gains (P < 0·01) than C lambs. The inclusion of fish meal in the diet increased fleece and offal weights (P < 0·05) and fleece-free empty body gains (P < 0·01). Much of the response was confined to the first increment of fish meal. The preceding growth pattern had little effect upon the response of the lambs to dietary supplements of fish meal.

The effects of live weight at weaning on carcass composition were studied with 104 Scottish Blackface lambs offered two diets differing in protein: energy ratio. Groups of lambs were slaughtered at initial live weights of 24·1 (s.e. 1·48) kg (LL) and 28·9 (s.e. 1·67) kg (IL) and at 33 kg, 38 kg, 43 kg, 53 kg and mature live weight.

Lambs were offered two diets — low protein: energy ratio (LP, 122 g crude protein (CP) per kg dry matter (DM): 10·4 MJ metabolizable energy (ME) per kg DM) and high protein: energy ratio (HP, 176 g CP per kg DM: 10·4 MJ ME per kg DM). The LP diet was offered ad libitum and the HP diet was restricted to a similar mean level. Muscle, fat and bone tissues in the carcass were separated and weighed and the carcass and non-carcass component tissues were analysed for chemical fat, protein and ash.

Daily live-weight gain (DLWG) of HP lambs (148 (s.e. 8·1) g/day) was significantly higher than that of LP lambs (118 (s.e. 8·1) g/day; P < 0·05) and food conversion ratios were lower up to a live weight of 43 kg (P < 0·05). There were no differences in intake or DLWG between LL and IL lambs. Mature live weight (73·3 (s.e. 1·79) kg) was not related to weaning weight or post-weaning diet.

There was no effect of diet on carcass composition at any slaughter weight but LL lambs had a higher fat proportion than IL lambs, which was significant (P < 0·05) at 33 kg only. During the feeding period, the increment of fat tissue per unit increase in live weight (348 (s.e. 15·8) g/kg LW) was not affected by live weight at the start of the diet. The difference between LL and IL lambs in fat proportion was directly related to the difference in weight gain required to reach slaughter weight. The difference was not a function of stage of maturity but only of weaning weight, itself largely determined by pre-weaning nutrition. At higher slaughter weights the relative difference decreased and became non-significant. Hence lambs lighter at weaning would be less suitable than heavier lambs for the production of light-weight lean carcasses.

In three experiments pregnant ewes (mean weight 72·5 kg) were subjected to different planes of nutrition on grass silage-based diets during mid pregnancy and, in factorial designed trials with ad libitum silage or ad libitum silage + concentrates in late pregnancy. The high plane of mid-pregnancy nutrition resulted in an average gain of 11·5 kg between weeks 7 and 14 of pregnancy while the low plane gave an average loss of 3·5 kg during this period. These differences did not affect lamb birth weight but ewes on the high plane were 7·2 kg heavier after lambing than those on the low plane. The effect of plane of nutrition during mid pregnancy on silage intake during late pregnancy was variable but there was some evidence of a greater reduction in intake during the last few weeks of pregnancy following the high plane of mid-pregnancy nutrition. The higher plane of nutrition in late pregnancy resulted in higher ewe live weights as well as higher lamb birth weights and highest lamb birth weights occurred following restriction in mid pregnancy and a high plane of nutrition in late pregnancy.

Plasma 3-hydroxybutyrate levels were variable but there was little evidence of an effect of mid-pregnancy nutrition although levels appeared to be increased by the low plane of nutrition in late pregnancy.

The effects of three variables; polysaccharidase inclusion level (0, 5 and 10 g/kg), moisture content (500, 600 and 700 g/kg dry matter (DM), and particle size (20, 5 and 2 mm), on the quality and degradation characteristics of ensiled rice straw were investigated. The polysaccharidase product used was shown to contain a broad spectrum of activities against polysaccharides typical of plant material. The major activities present being: mixed link glucanase, xylanase and both endo- and exo-cellulase. The straw treated with polysaccharidase had a lower final pH (5·21, 4·87, 4·82; P < 0·01), higher concentrations of lactic acid (1·98, 3·90, 3·67 g/kg; P < 0·01), a lower content of neutral-detergent fibre (689, 630, 621 g/kg DM; P < 0·01) and a higher solubility, measured as washing losses from nylon bags (152, 196, 212 g/kg DM; P < 0·01) for the 0, 5 and 10 g/kg polysaccharidase treatments respectively. The samples were subsequently incubated in nylon bags in the rumen of three sheep for 8, 16, 24, 48 and 72 h to estimate degradation rate and potential degradability using the expression p = a + b (1 – e−ct) where p is degradability at time t and a, b and c are constants. While there was no effect of moisture content or physical form of the straw, the degradation rate constant (c) was increased (P < 0·01) by the addition of polysaccharidase. The maximum potential degradability (a + b), however, was not altered by any of the treatments. The values for c were 0·0498, 0·0677 and 0·0817 per h and for (a + b) were 62·4, 62·1 and 62·8 g/100 g DM for the 0, 5 and 10 g/kg polysaccharidase enzyme additions respectively. It is concluded that the use of polysaccharidase enzymes can assist in the preservation of wet straw and can result in improved degradation characteristics.

Two experiments were carried out with sheep, to characterize fodder beet in terms of its effects on rumen function. In experiment A, a study was made of the effects of supplementing hay with fodder beet (FB) on rumen pH and volatile fatty acid (VFA) concentration compared with two control supplements of either barley/maize (BM) or molassed sugar-beet shreds (SBP). Hay was offered with all three supplements in a 50: 50 ratio on a dry matter (DM) basis. The mean rumen pH for the fodder beet diet was 6·34 and intermediate between two controls (BM 6·20 and SBP 6·38). There was no significant difference in rumen concentration of total VFA for the three different diets (FB, SBP and BM) but there were highly significant effects due to diet for acetic and propionic acid molar proportions (P < 0·001). Molar proportion of propionic acid for diets FB, BM and SBP were 0·2064, 0·2221 and 01880 respectively. The loss of DM from nylon bags incubated in the rumen of sheep given the test diets was 471, 447 and 486 g/kg for FB, BM and SBP respectively. In experiment B, the rate of in sacco organic matter (OM) disappearance of the three supplements were compared in sheep given a constant high forage diet (900 g/day hay DM + 200 g/day compound food DM). There were highly significant differences in rates of OM disappearances for the supplements (P < 0·001). The losses of OM measured after 3 h incubation in the rumen were 767, 608, 378 and 236 g/kg for fodder beet, barley/maize, molassed sugar-beet shreds and hay respectively.

A two-pool model of tritiated water kinetics was investigated as a means of partitioning total body water into empty body water and gut water in 17 lactating goats. Empty body water, gut water and total body water were of a similar magnitude to, and highly correlated with, a rapidly equilibrating tritiated water pool, a more slowly equilibrating pool and the sum of these two pools, respectively.

Empty body fat was poorly correlated with both live weight and empty body weight (R2 = 0·42 and 0·51, respectively). However, there was a strong inverse relationship between the water and fat contents of the empty body. Consequently, empty body fat was accurately predicted by a multiple regression equation which included both empty body weight and empty body water as independent variables (R2 = 0·97). Substitution of these variables with estimates derived from tritiated water kinetics still resulted in a high correlation (R2 = 0·88). Tritiated water kinetics offered little improvement over live weight alone in the prediction of empty body protein, empty body ash or fat-free empty body.

The relationships between the sucking behaviour of newborn piglets during bouts of sucking and their serum immunoglobulin G (IgG) levels at 12 h of age were investigated in 274 Landrace × Yorkshire piglets from 24 second parity Yorkshire sows. Mean IgG level differed between litters but was not related to the number of live-born piglets or the mean birth weight of the litter; in addition, the amount of variation in IgG level within a litter was not related to the number of live-born piglets or the amount of variation in birth weight of the piglets.

Within a litter, lower serum IgG levels were found in piglets of birth orders greater than eight and piglets that had a very low frequency of sucking bouts. The piglets that had the higher IgG levels within a litter were those that started to suck sooner, sucked from many teats and won more of their teat disputes. Piglets that were involved in fewer teat disputes within a litter or took a greater proportion of their sucking bouts on anterior teats did not have higher IgG levels. Piglets that died differed from their surviving litter-mates in having lower IgG levels and having lost weight during the first 12 h after birth. Within a litter, IgG levels were not related to 10-day weight gain. However, litters with a lower mean IgG level also had a lower mean 10-day weight gain. It is suggested that a low mean IgG level in a litter reflects or predicts a low milk production by that sow.

Differential rates of genetic change in litter productivity, growth and carcass traits were estimated for the pig populations of six British breeding companies from their relative performance between 1972 and 1981 in the Meat and Livestock Commission's Commercial Pig Evaluation. Pigs were grown on one of two feeding regimens and slaughtered at one of three live weights (61, 93 and 118 kg).

Important differentials were found for a number of traits. Annual rates of change in litter size at birth differed by 0·34 pigs between the two extreme populations. The range between populations for live-weight daily gain (ad libitum feeding) was 20 g, for lean weight daily gain (restricted feeding) it was 6 g, and for lean weight food conversion (feeding regimens pooled) it was 28 g food per g gain. The average annual rate of change of the six company populations was compared with the rate achieved by the purebred Large White breed over the period 1972 to 1977. For mean piglet birth weight the rate was 30 g higher for the company populations, whilst for carcass weight daily gain it was 24 g higher.

There was little evidence for population × feeding regimen interactions except that companies ranked differently in average daily food intake, live-weight daily gain and carcass weight daily gain on the two feeding regimens. On limited evidence, population × slaughter weight interactions were also unimportant.

Abstract The effects of two temperatures (thermoneutral, 22°C v. fluctuating high temperature, 35·22°C), four food levels (ad libitum and three levels of food restriction) on growth and energy retention of growing pigs (male and female) was investigated in a 2 × 2 × 4 factorial experiment involving 48 individually penned pigs from 20 to 50 kg live weight. A second experiment was conducted over the 50 to 80 kg liveweight range using a 2 × 2 × 3 design.

Mean daily digestible energy (DE) intake, daily gain, P2 backfat thickness, carcass fat proportion, total body energy retained and body energy retained as protein did not differ significantly between the temperature treatments in either experiment. Mean carcass protein proportion was greater at 35·22°C than at a constant 22°C.

With pigs given food ad libitum during the 50 to 80 kg phase, an increase in temperature from 22°C to 35·22° reduced daily DE intake by 4·1 MJ (38·9 v. 34·8 MJ or 300 g food per day), reduced energy retention by 2·3 MJ/day (15·6 v. 13·3 MJ/day), and increased carcass protein proportion by 11 g/kg (142 v. 153 g/kg).

There was a significant interaction between the effects of sex and temperature on P2 backfat thickness over both live-weight ranges. Female pigs housed at 35·22°C had 2·6 mm less P2 backfat at 50 kg (13 v. 15·6 mm) and 2 mm less at 80 kg (20 v. 22 mm) compared with females housed at 22°C. The P2 backfat thickness of male pigs did not vary at 50 kg (13·2 v. 13·5 mm) but when housed at 35·22°C males had 1·4 mm more P2 backfat at 80 kg (18·2 v. 19·6 mm).

Fifty entire male pigs between 7 and 28 days and 50 entire male pigs between 28 and 56 days of age' were given basal diets containing peanut meal as the protein supplement. These diets contained 4·5 to 6·1 g threonine per kg and were supplemented with graded additions of synthetic L-threonine.

It was found that the amount of threonine required for maximum performance and nitrogen retention was 6·6 g/kg dry matter (DM) between 7 and 28 days of age and 5·4 g/kg DM between 28 and 56 days of age. These values were calculated to correspond to 0·43 and 0·36 g threonine per MJ digestible energy.

The concentration of threonine in the blood plasma did not give a clear indication of the threonine requirement of the pigs.

Two trials were conducted with eight yearling camels with an average intial body weight of 300 kg, to evaluate protein and energy values of lucerne hay and barley grains. In each trial, eight animals were randomly allotted to two different dietary treatments of coarsely ground lucerne hay or lucerne hay + barley grain (50:50) in such a way that two animals in each of the two blocks received the same ration. Each trial consisted of a 10-day preliminary period followed by a 7-day collection period during which total urine and faeces collections were made, and samples were processed and composited for later analysis.

All animals consumed daily an average of about 5 kg food divided in two equal meals. The apparent digestibility coefficients for organic matter, crude protein, neutral-detergent fibre and cellulose of the lucerne hay ration improved respectively from 0·615, 0·662, 0·455 and 0·555 to 0·736, 0·655, 0·547 and 0·589, as a result of incorporating 500 g/kg barley grain in place of hay in the diet. Even though there was no difference in the proportion of nitrogen retained relative to intake, the proportion of nitrogen retained relative to that absorbed was higher (P < 0·05) in the lucerne + barley group (0·769) than in the lucerne-only group (0·747). On a dry-matter basis, the feeding value in camels of digestible protein (g/kg), total digestible nutrients (g/kg), digestible energy (MJ/kg), metabolizable energy (MJ/kg), net energy maintenance (MJ/kg), net energy lactation (MJ/kg) and net energy gain (MJ/kg) were respectively 118, 552, 10·0, 8·4, 5·4, 5·0 and 2·1 for lucerne hay and 80, 800, 14·6, 12·1, 8·4, 8·8 and 5·0 for barley grain (calculated by difference).

Two trials were conducted in 1986 on artificial insemination of female fallow deer at fixed intervals from the cessation of oestrous synchronization treatment. Semen had been collected previously from mature bucks by electroejaculation and extended in sodium citrate/egg yolk diluent.

In the first trial involving a comparison of the fertilization rates of fresh and frozen-thawed semen delivered intravaginally, 57 does each received a single intravaginal progesterone-releasing device (CIDRtype S, Carter Holt Harvey Plastic Products Group Ltd, Hamilton, NZ) for a 14-day period early in the 1986 breeding season. All does were inseminated intravaginally with either fresh (no. = 26) or frozenthawed (no. = 31) semen (85 × 106 motile spermatozoa per inseminate) at 48 h after CIDR removal. The apparent conception rates for the two types of semen were 65·4% and 64·5% respectively (P > 0·1) and the actual fawning rates were 500% and 48·4% respectively (P > 0·1).

In the second trial involving an investigation of the feasibility of laparoscopic intrauterine insemination, 55 does were synchronized as for the first trial. At 56 to 58 h from CIDR removal, the does were anaesthetized and laparoscopically inseminated with frozen-thawed semen (85 × 106 motile spermatozoa per animal) by direct injection into both uterine horns. Anaesthesia was reversed immediately following artificial insemination. The apparent conception rate was 47·3% and the actual fawning rate was 41·8%.

Data from both trials indicate that reasonable fawning rates can be obtained for artificially inseminated fallow deer. Between 11 and 25% of does expected to fawn did not and this may represent embryonic mortality attributable to the method of oestrus/ovulation synchronization.