Four concentrate mixtures were given with grass silage to 52 cows in early lactation in an 8-week randomized block production trial. A further eight cows were used to measure apparent digestibilities of the total diets in a double 4 × 4 Latin-square trial.

The concentrates contained varied proportions of barley, soya bean meal (soya) and formaldehyde-treated soya bean meal (treated soya) together with fixed proportions of wheatfeed and molasses. Crude protein (CP) concentrations in the concentrate mixtures and sources of supplementary protein were 133 g/kg air-dry concentrate, soya (A); 130 g/kg, treated soya (B); 187 g/kg, soya (C); 169 g/kg, soya plus treated soya (D). In the production trial, 9 kg concentrates were given daily together with silage ad libitum, whilst in the digestibility trial the daily ration was 7·6 kg concentrates and 6·6 kg silage dry matter (DM). The silage contained 462 g DM per kg and 140 g CP per kg DM with an in vitro digestibility of DM of 0·7.

The digestibilities of DM, organic matter and energy showed similar trends. Cows given treatments A and B had significantly lower digestibilities of energy than did those given treatments C and D.

Nitrogen digestibility was highest for cows given treatment C and lowest for those given treatments A and B. Silage DM intake and live-weight change were unaffected by treatment during weeks 1 to 8, all treatment groups being in positive live-weight balance in this period.

Milk yields during weeks 1 to 8 were 18·8 (A), 19·6 (B), 20·3 (C) and 20·7 (D) kg/day. Yields for cows given treatments C and D were significantly higher than those for cows given treatment A. There were no differences between treatments for any constituent of milk, but protein concentration in milk tended to be lower for cows given treatment D. During weeks 9 to 20, there were no significant residual effects of treatment upon milk yield or composition.

Parallel regression analysis of milk yield and yields of milk constituents upon CP concentration in the concentrate indicated significant effects of CP concentration on yield of milk, milk fat, protein and lactose during weeks 1 to 8. When examined during weeks 1 to 20 the responses to increased CP concentration were non-significant. The analysis showed a significant positive milk-yield response to formaldehyde treatment during weeks 1 to 8 and 1 to 20. The response in lactose yield was also significant during weeks 1 to 8 and 1 to 20. There was a trend, though not significant, towards an increased milk-fat yield during weeks 1 to 8 for the formaldehyde treatment, whilst protein yield was unaffected.

Three change-over design experiments investigated the origin of hydrogen sulphide in the rumen head-space gas of dairy cows, comparing the effects of single iso-S additions of methionine, cysteine and sodium sulphate, as well as the effects of single meals of fresh ryegrass or white clover. The concentration of hydrogen sulphide in rumen gas declined close to zero within 4 h after withdrawal of the previous feed. Sulphur sources were then given to cows and concentrations of hydrogen sulphide recorded in rumen head-space gas at 30-min intervals. Cysteine addition (8 g) led to a rapid (within 30 min) and a large (490 and 957 p.p.m. respectively in two experiments) increase in hydrogen sulphide concentration. Concentrations were significantly less following methionine addition. Increasing levels of cysteine addition led to significant increases in hydrogen sulphide concentrations ( P < 0.001 for the linear effect), although peak hydrogen sulphide was delayed and concentrations remained higher for longer with the highest (12 g) addition of cysteine ( P < 0.01 for the ‘cysteine level’ × ‘time’ interaction). The increase in concentration of hydrogen sulphide from sodium sulphate was smaller (230 p.p.m.) and slower (2 h) than for cysteine. Despite the much higher intake of cystine for white clover in comparison with perennial ryegrass ( P < 0.001), there was almost no increase in hydrogen sulphide concentration in rumen head-space gas from cows fed white clover. It seems likely that this is associated with the use of sulphur to produce thiocyanate to detoxify the hydrogen cyanide from cyanogenic white clover.

A study was undertaken to compare the chemical composition of Texas No. 2 hybrid yellow sorghum with that of a traditional brown-seeded variety and also their digestibility and nitrogen retention in the growing pig. Dry matter, crude protein and gross energy contents and amino acid composition were similar in the two varieties but brown-seeded sorghum had a markedly higher tannin content. In diets containing 70% of either yellow or brown sorghum, N retention was marginally higher on the yellow sorghum diet and apparent digestibility of dry matter, nitrogen and gross energy was improved (0·07, 0·06 and 0·12 units respectively). The improvements in digestible energy and crude protein content of the yellow sorghum diet over the brown-seeded one were 10% and 6% respectively. In a subsequent trial 16 pigs were individually and scale-fed each of the diets over the live-weight range 28 to 81 kg. Growth rates and feed conversion ratios were better on the yellow sorghum diet (10%) but sorghum variety did not influence killing-out percentage, deposition of backfat or area of eye muscle in cross-section.

Four groups of calves (10 bulls, 10 steers, 10 heifers and 10 ovariectomized heifers) of Simmental- Hereford breeding were individually given a high-energy diet from 10 to 16 months of age. At the end of the experiment, the 9-10-11th rib section was dissected into fat, lean and bone and chemical analysis was performed on the dissected soft tissue. For each group, the relationship between food intake and change in body weight was examined by a method designed to separate intake into its simultaneous maintenance and gain components: least-squares estimates for the maintenance coefficient (βm, kg/day per kg body weight) and the gain coefficient (βg, kg food per kg gain) were obtained for each animal. Conventional measures of food conversion ratio (kg food per kg gain) were examined on both common age and common weight-gain bases. Bulls, followed by steers, accumulated the most lean and least fat while heifers and ovariectomized heifers accumulated the least lean and most fat. Maintenance coefficients (βm) were lower in males than in females but did not differ within gender. Gain coefficients (βg) did not differ among the groups, although the coefficients appeared to be similar within gender. Food conversion ratio computed over a common age interval did not differ among groups. Food conversion ratio computed over common weight intervals was lowest in bulls followed in increasing order by steers then the two female groups. It is concluded that males grow more efficiently than females while accumulating more lean and less adipose tisue and that this greater efficiency is achieved by consuming less food per unit of body weight for maintenance, leaving proportionately more of the total intake available for gain.

Forty Landrace × (Landrace × Large White) gilts were randomly assigned at 70 days of age to each of two rearing treatments. The two treatments were: (1) gilts reared with gilts but kept in complete isolation from other pigs, and (2) gilts reared with visual, aural, olfactory and limited tactile contact with a mature boar. At 160 days of age, all gilts were subjected to a pen change and housed adjacent to either a mature boar for the first time, or to a different mature boar from that with which they had contact during the rearing phase. In addition, gilts were exposed to a mature, vasectomized boar for 30 min each day. They were served twice at second oestrus and the reproductive tracts were examined at slaughter 21 days later to determine ovulation rate and embryo survival. The presence of a mature male during the rearing phase had no effect on the attainment of puberty. There were no significant differences between treatments 1 and 2 for age at puberty (168·1 and 166·9 days respectively), weight at puberty (74·0 and 75·7 kg respectively) and the interval from movement and boar introduction to puberty (8·3 and 7·4 days respectively). The rearing treatments also had no effect on ovulation rate or embryo survival.

Urea production may be impaired in intrauterine growth restriction (IUGR), increasing the risk of toxic hyperammonaemia after birth. Arginine supplementation stimulates urea production, but its effects in IUGR are unknown. We aimed to determine the effects of IUGR and arginine supplementation on urea production and arginine metabolism in the ovine foetus. Pregnant ewes and their foetuses were catheterised at 110 days of gestation and randomly assigned to control or IUGR groups. IUGR was induced by placental embolisation. At days 120 and 126 of gestation, foetal urea production was determined from [14C]-urea kinetics and arginine metabolism was determined from the appearance of radioactive metabolites from [3H]-arginine, both at baseline and in response to arginine or an isonitrogenous mixed amino acid supplementation. Urea production decreased with gestational age in the embolised animals (13.9 ±  3.1 to 11.2 ±  3.0 μmol/kg per min, P ≤ 0.05) but not in the controls (13.3 ±  3.5 to 14.8 ±  6.0 μmol/kg per min). Arginine supplementation increased urea production in both groups, but only at 126 days of gestation (control: 15.0 ±  8.5 to 17.0 ±  9.4 μmol/kg per min; embolised: 11.7 ±  3.1 to 14.3 ±  3.1 μmol/kg per min, P ≤ 0.05). Embolisation reduced foetal arginine concentrations by 20% ( P ≤ 0.05) while foetal arginine consumption was reduced by 27% ( P ≤ 0.05). The proportions of plasma citrulline and hydroxyproline derived from arginine were reduced in the embolised animals. These data suggest that foetal urea production and arginine metabolism are perturbed in late gestation after placental embolisation.

The heart rate (fH) and the energy expenditure (EE) of seven Hintenvaelder (Bos taurus) draught oxen and three zebu (Bos indicusj oxen were measured, while the animals were standing, walking and pulling different loads. Linear regressions for all animals relating EE to fH were highly significant (P < 0·001). The standard errors of the estimate expressed as a percentage of the mean EE (PE) ranged from ±6·7% to ±10·5%. Two animals with PE ±13·7% and ±17·1% were beyond that range. One year later, fH and EE were measured on six of the original seven Hinterwaelder oxen while the animals were standing and walking on a treadmill, on the level and at gradients of 3%, 6% and 9%. In the two experiments mean slope and mean intercept of the regressions of EE on fH were not different (P > 0·05). Irrespective of the kind of work (draught work or lifting work),fH allows a reliable prediction to be made of the EE of working oxen.

Results of four experiments involving a total of 124 pigs covering the growth period between about 40 and 210 lb. live-weight indicated that:

1. The growth rate and efficiency of food utilisation of pigs receiving liquid skim milk up to a maximum of 5¼ pints per head per day, was better than that of pigs receiving a balanced all-meal diet. This was equally so whether the liquid skim milk was fed throughout the growing period or was abruptly removed from the diet at either about 75 lb. or 120 lb. live-weight, provided the all-meal diet fed subsequently contained adequate protein.

2. The addition of 0·1% copper sulphate to the meal fed with liquid skim milk significantly improved the growth rate and efficiency of food conversion.

3. The addition of 0·2% dl-lysine and 0·1% dl-methionine to the meal fed with liquid skim milk had no effect on the performance of the pigs.

4. Withdrawal of a protein supplement from the rations of pigs after they reached about 120 lb. live-weight adversely affected their performance.

Three mature rams in each of four naturalized breeds (Romney, Border Leicester, Cheviot and Dorset Down) and two or three 15-mo-old rams in each of four recently imported ‘exotic’ breeds (Finnish Landrace, East Friesian, German Whiteheaded Mutton and Oxford Down) were mated to between 14 and 32 Romney ewes in a pedigree pen-mating system at Mana Island, New Zealand. Two or three 60-min observations of mating behaviour were made on each ram.

There were no significant differences in mating behaviour scores between groups of breeds, but the mature rams of the naturalized breeds were more fertile than the young rams of the exotic breeds (76% and 57% ewes not returning to first mating respectively). Within the young exotic breed group there were significant differences between breeds in number of serves per test, interval to first mount and fertility. Fertility was negatively correlated with time to first mount.

In cattle, the detection of very early endometrial responses is considered to be hampered by the presence of only a single embryo. Therefore, we have previously developed a model of multiple embryo transfer to circumvent this hindrance. In this work, we analysed embryo–maternal interactions in the bovine uterus on day 8 of development while comparing the presence of multiple v. single embryos using embryo transfer and artificial insemination, respectively. Concentration of proteins (β-actin, NFkB, clusterin and immunoproteosome 20S β5i subunit–i20S), by western blot, and hexoses (glucose and fructose) were measured in paired samples of uterine fluid (UF) from the same animal with and without embryos in the uterus and were compared with UF obtained after artificial insemination. Prostaglandin (PG) F2α and PGE2 concentrations were also analysed in blood plasma. The four proteins analysed and hexoses were unaffected by the presence of one or more embryos in the uterus. However, blood PGF2α showed similar, significant increases with one or more embryos over cyclic animals; such changes were not observed in blood PGE2. Although multiple embryo transfer may appear to be non-physiological, we showed that the uterus, at the very early embryonic stages, does exhibit physiological reactions. Multiple embryo transfer can, therefore, be used for studies of very early embryo–maternal interactions in vivo in monotocous species.

Sodium and chloride are the key factors maintaining normal osmotic pressure (OSM) and volume of the extracellular fluid, and influencing the acid–base balance of body fluids. The experiment was conducted to investigate the effects of dietary Na+ and Cl− level on growth performance, excreta moisture, blood biochemical parameters, intestinal Na+–glucose transporter 1 (SGLT1) messenger RNA (mRNA), and Na+–H+ exchanger 2 (NHE2) mRNA, and to estimate the optimal dietary sodium and chlorine level for yellow-feathered chickens from 22 to 42days. A total of 900 22-day-old Lingnan yellow-feathered male chickens were randomly allotted to five treatments, each of which included six replicates of 30 chickens per floor pen. The basal control diet was based on corn and soybean meal (without added NaCl and NaHCO3). Treatments 2 to 5 consisted of the basal diet supplemented with equal weights of Na+ and Cl−, constituting 0.1%, 0.2%, 0.3% and 0.4% of the diets. Supplemental dietary Na+ and Cl− improved the growth performance (P<0.05). Average daily gain (ADG) showed a quadratic broken-line regression to increasing dietary Na+ and Cl− (R2=0.979, P<0.001), and reached a plateau at 0.1%. Supplemental Na+ and Cl− increased (P<0.05) serum Na+ and OSM in serum and showed a quadratic broken-line regression (R2=0.997, P=0.004) at 0.11%. However, supplemental Na+ and Cl− decreased (P<0.05) serum levels of K+, glucose (GLU) and triglyceride. Higher levels of Na+and Cl− decreased duodenal NHE2 transcripts (P<0.05), but had no effect on ileal SGLT1 transcripts. The activity of Na+ /K+-ATPase in the duodenum decreased (P<0.05) with higher levels of dietary Na+ and Cl−. In conclusion, the optimal dietary Na+ and Cl− requirements for yellow-feathered chickens in the grower phase, from 22 to 42 days of age, to optimize ADG, serum Na+, OSM, K+ and GLU were 0.10%, 0.11%, 0.11%,0.17% and 0.16%, respectively, by regression analysis.

There is increasing concern about welfare of laying hens in cages, and one aspect of this topic relates to bone fragility. Therefore, bone anabolic components such as bovine lactoferrin (bLF) may be an effective strategy to maintain the integrity and health of bones. A total of 1080 eggs were divided into four groups with three replicates, each comprising 270 eggs; (1) control group was injected with 100 μl of normal saline per egg; (2, 3 and 4) groups including 22.5 (low), 45 (medium) and 67.5 µg (high) of bLF in 100 µl of normal saline per egg. Eggs were incubated and after hatching, chicks were reared to 28 weeks of age. Tibia measurements were obtained at hatch and at 28 weeks of age. Tibia weight at hatch, was not influenced by in ovo injection of bLF in comparison with the control. Eggs injected with the high concentration of bLF (67.5 µg of bLF per egg) showed significant strengthening in laying-hen tibias at 28 weeks of age, as measured by ultimate force and bending stress, compared with the control. Egg weights from hens treated with this concentration of bLF were also significantly greater than the control. Our data suggest that tibia cortical thickness is a suitable variable for evaluating bone status reflecting bone integrity and strength. The present study also shows that bLF (67.5 µg of bLF per egg) injected into layer breeder eggs before incubation can be used to improve bone strength and egg weight of laying hens at 28 weeks of age, while having no detrimental effect on embryo hatchability.

In many countries, male pigs are castrated to prevent boar taint, but this practice raises concerns about animal welfare and reduces the production efficiency of pork. The objective of this study was to develop dietary manipulations to prevent boar taint. We evaluated the effectiveness of adding activated carbon (AC) or Tween-60 (Tween; polyoxyethylene sorbitan monostearate) to pig finishing diets to reduce levels of androstenone (AND) and skatole in plasma and fat of entire male pigs. Boars (159 ± 2 days of age at the start of the experiment) were fed diets supplemented with either 5% AC or 5% Tween for 28 days followed by either 14 or 28 days of recovery. Plasma samples were collected at experimental days 0, 7, 14, 21, 28, 42 and 56, and backfat biopsies were taken at experimental days 0, 28, 42 and 56. Feeding AC significantly (P < 0.05) reduced the levels of AND in plasma by day 28 compared to day 0 and by day 42 in fat compared to day 0. AC treatment also decreased levels of oestrone sulphate (E1S) in plasma by day 7 compared to day 0. Treatment with Tween significantly decreased (P < 0.05) the levels of plasma AND by day 28 from levels at day 0. Tween treatment did not significantly affect levels of fat AND or plasma E1S compared to day 0; however, fat AND levels decreased between days 28 and 42 following treatment with Tween (P < 0.05). Levels of plasma E1S, plasma AND and fat AND for control boars remained constant throughout the experiment. Skatole plasma concentrations were very low and did not vary significantly (P > 0.05) from day 0 for any treatment, but fat skatole levels decreased by day 42 in the Tween treatment group. Importantly, there was no difference in growth rate between the control and experimental groups. We conclude that adding AC or Tween to finishing diets for boars can reduce the levels of plasma and fat AND, but further work is needed to confirm the effects of these treatments on reducing fat skatole levels.

It is a popular belief, supported by several scientific studies (Vaughan, 1971; McPhee and Laws, 1976; Fredeen and Sather, 1978; Sather and Fredeen, 1982) that leg weakness will diminish in young stock of breeding age after they are transferred from confinement housing to pasture lots. However, Nakano, Aherne and Thompson (1981) working with boars from the Canadian Swine ‘Record of Performance’ (ROP) testing programme found that no improvement in gait resulted after the animals were transferred from confinement housing with solid concrete flooring to pasture lots. The number of animals in the study was limited. All of these reports dealt only with the recovery of pigs from leg weakness and did not include pigs with sound legs at the beginning of the pasture period (approx. 90 kg live weight).

The intake and digestibility of diets containing dried grass supplemented with either molasses or tapioca was studied with 12 Friesian steers in two experiments, using a Latin square design. Three periods were used, each containing 3 weeks preliminary followed by a 10-day collection period. In both experiments long, artificially dried grass was given to appetite (treatment A). The other treatments in Experiment 1 were 25% molasses plus 75% dried grass (B) and 50% molasses plus 50% dried grass (C). In Experiment 2 the treatments were 21% tapioca plus 79% dried grass (D) and 42% tapioca plus 58% dried grass (E). There was no significant difference in dry matter or organic matter intake between the diets, though the intakes in both experiments tended to be lower when the dried grass was supplemented with either molasses or tapioca than when it was given alone. Nor were there any significant differences in the digestibility of dry matter or organic matter between the diets in either experiment. In both experiments the digestibility of crude fibre was significantly lower (P<0·05) when either molasses or tapioca was given with the dried grass than when the grass was offered alone.

Japanese Black cattle (Wagyu), deposit much higher amounts of intramuscular fat, known as marbling, than other breeds of cattle. To determine whether this unique fat deposition is attributable to the somatotropic axis, we compared pulsatile growth hormone (GH) secretion, plasma levels of insulin-like growth factor-1 (IGF-1) and cellular density of somatotrophs (GH-expressing cells) in the anterior pituitary glands of Japanese Black and Holstein steers. Blood samples were withdrawn every 15 min for 6 h from 14 Japanese Black and 12 Holstein steers at about 17 months of age, and GH and IGF-1 concentrations were determined. The distribution and proportion of GH-expressing cells were analysed by immunohistochemistry combined with point-count morphometry in pituitaries from six steers from each breed aged about 18 to 21 months. Overall mean and baseline plasma GH concentrations were lower (P < 0·001) in Japanese Black than Holstein steers. In addition, Japanese Black had smaller (P < 0·05) amplitudes of GH secretory pulses than Holstein steers, whereas the GH pulse frequency did not differ between the breeds. Japanese Black steers also had lower (P < 0·001) plasma levels of IGF-1 than Holstein steers. The marbling score of Japanese Black steers was higher (P < 0·001) than that of Holsteins at the same carcass weight. The proportion of GH-expressing cells was smaller (P < 0·05) in Japanese Black than Holstein steers at the hind dorsal and hind ventral regions of the adenohypophysis. Thus, in Japanese Black and Holstein steers, the breed difference in the relative density of GH-expressing cells corresponded to that in profiles of pulsatile GH secretion. These results suggest that the features of the somatotropic axis intrinsically differ between Japanese Black and Holstein cattle and that these features may be partly responsible for the genetic ability of the former to deposit greater amounts of marbling fat and for the smaller frame of Wagyu cattle.

The discounted gene flow method was used to study the effect of varying financial discount rates and accounting period on the present value of the genetic merit conferred by each insemination.

Over the range from 8% to 16%, each 1% increase in the discount rate reduces the value of the dairy and beef consequences of an insemination by about 5% and 4% respectively, Virtually all of the economic benefit arising from an insemination is complete within 20 years, with about 90% of it being realized in the first 10 years and 98% in the first 15 years.

Fifty weaned store lambs approximately 7-month-old were used in an experiment designed to assess their protein requirements and utilization. At the beginning of the experiment a random sample of 10 animals were slaughtered and their loin joints analysed. The remaining 40 were allocated at random to four dietary treatments (T1, T2, T3, T4) comprising four crude protein intakes at a constant energy intake. The experiment was divided into two periods. During period 1 (48 days) the dietary crude protein intakes were 58 (T1), 111 (T2), 170 (T3), and 198 (T4) g/day with a mean digestible organic matter intake (DOMI) of 578 g/day. During period 2 (55 days) the corresponding crude protein intakes were 89, 157, 215, 251 and the DOMI was 678 g/day.

Digestibility and nitrogen balance trials were carried out on two animals from each treatment in period 1 and on six animals on each treatment in period 2. At slaughter the loin joints from five animals on each dietary treatment were chemically analysed.

The only significant effect on live-weight gain of varying protein intake was a lower gain on the lowest protein intake (T1) in period 1. It was estimated that the optimum ratio of digestible protein intake (g) to digestible energy intake (meals) for live-weight gain in period 1 was approximately 30 : 1 and in period 2 approximately 21 : 1. There was a significant increase in killing-out percentage with increasing crude protein intake. The digestibility of dry matter and nitrogen increased with increasing crude protein intake. There was a significant quadratic relationship between the apparently digested nitrogen intake in g/day (X) and nitrogen retained in g/day (Y). The regression equation was

Y = −0·008X2 + 0·537X + 0·682

Liver copper levels decreased with increasing crude protein con-centration in the diets.

Post-Partum anoestrus is lengthened by a thin body condition (Whitman, 1975) and malnutrition (Holness, Hopley and Hale, 1978). Post-partum nutrient intake has been implicated in both pituitary (Rutter and Randel, 1984) and ovarian (Wiltbank, Rowden, Ingalls and Zimmerman, 1964) function. Other post-partum studies, however, have shown a negligible effect of nutrition on either the pituitary (Spitzer, Niswender, Seidel and Wiltbank, 1978) or the ovary (Carstairs, Morrow and Emery, 1980). The lack of agreement among these studies may be due to an inability to control nutrient intake in all cows in a group feeding situation, or to a lack of nutrient restriction in many of the cows on a mildly restrictive diet. Furthermore, it is not clear when post-partum energy restriction is most deleterious to fertility. The objectives of this study were to examine the effect of a known individual energy intake on (i) post-partum length, and (ii) the ovarian follicular population at different stages post partum.