Effect of microwave treatment on lucerne fodder

Preliminary research has suggested that in vitro dry matter disappearance of some poor-quality fodder materials can be improved by microwave treatment. A laboratory-scale experiment that treated 50-g samples of lucerne hay in a 750-W microwave oven for 0, 40 and 80 s revealed that dry matter percentage increased by 1.7% as microwave treatment time increased from 0 to 80 s. The in vitro dry matter disappearance increased by 14.9% as microwave treatment increased from 0 to 80 s; however, there was no significant change in crude protein due to excessive variability in the results. This experiment was followed up with a larger-sample experiment in which 25-kg bags of lucerne fodder were treated for 7.5, 15, 22.5 or 30 min in an experimental 6-kW microwave chamber. Dry matter percentage increased by 7.2% as microwave treatment time increased from 0 to 30 min. Microwave treatment significantly increased dry matter disappearance during the in vitro digestion study; however, there were no significant differences between the various microwave treatment times. The 15-min treatment resulted in the greatest increase in dry matter disappearance (5.9%). The crude protein retained in the digestion residues increased by 19.2% as microwave treatment increased from 0 to 30 min. These laboratory studies were followed up with an animal response study in which 22 12–14-month-old Merino wethers were randomly allocated into either a group receiving a maintenance ration of untreated lucerne or a group receiving the same weight of microwave-treated lucerne. The average weight of the control group fluctuated around their starting weight during the 5-week-long trial, as would be expected from feeding a maintenance ration. By the end of the trial their average weight was 0.4% higher than when they started. However the group being fed the microwave-treated lucerne gained 8.1% of their initial bodyweight by the end of the trial.

519. INFLUENCE OF THE DURATION OF CIDR INSERTION ON OVARIAN RESPONSES IN AN eCG PROGRAM DURING NON-BREEDING SEASON IN EWES

The aim of this study was to investigate the effect of 14 versus 7 days CIDR insertion before eCG treatment on superovulatory responses during non-breeding season in ewes. 10 Iranian Shall ewes, between 2 and 3 years old were kept inside during the experiment period and were fed a live weight maintenance ration. Ewes were randomly assigned to 1 of 2 groups. CIDR was inserted to the ewes of group 1 for 14 days and for 7 days to group 2. Each ewe received 1500 IU eCG on the day of CIDR removal. Ovarian follicular activity was monitored by transrectal ultrasonography on the days of eCG treatment, estrus, and 7 days after estrus to monitor the number of corpus lutium. During examination the animals were held in a standing position. Scanning of both ovaries was recorded using a MP4 player. The number of medium and large follicles (≥3 mm in diameter) were recognized, measured and mapped to their location using printed images of both ovaries. Data were analyzed using GLM procedure of the SAS. The results presented in Table 1 shows that the ovarian responses in terms of the number of ≥3 mm follicles at estrus is greater (P<0.05) in group 1 than group 2 ewes. The mean number of CL after eCG injection in group 1 and 2 were also significantly different (3.6±0.24 vs 2.4±0.51; P<0.05). The results showed that the 14 days synchronization before eCG treatment during non-breading seasons in ewes had the beneficial effects on ovarian responses.

516. THE EFFECTS OF eCG INJECTION ON SUPEROVULATORY RESPONSES BEFORE VERSUS AFTER CIDR REMOVAL IN IRANIAN SHALL EWES

The aim of this study was to investigate the effects of eCG injection on ovarian responses 2 days before or immediately after CIDR removal in a superovulation program during non-breeding season in Iranian Shall ewes. 12 ewes were kept inside for the duration of the experiment and were fed a live weight maintenance ration. The ewes were synchronized by CIDR. The day of CIDR insertion was considered as the starting point of the experiment (day 0). The ewes received 1500 IU eCG on day 12. Ewes were randomly assigned to 1 of 2 groups, and CIDR removed on days 12 and 14 in groups 1 and 2, respectively. Ovarian follicular activity was monitored by transrectal ultrasonography daily from the initiation day of superovulatory stimulation (day 12) until the day of estrus (day 14), and once 7 days after estrus (day 21) to monitor the number of corpus lutium. During examination the animals were held in a standing position. Ultrasonographic scanning of both ovaries was recorded using a MP4 player. The number of medium and large follicles (≥3 mm) were recognized, measured and mapped to their location using printed images of both ovaries. Data were analyzed using GLM procedure of the SAS. The results presented in Table 1 showed that the ovarian responses in terms of the number of ≥3 mm follicles at estrus and CL 7 days later were greater (P<0.05) in group 1 ewes. The results indicated that the superior time for eCG injection is on the day of CIDR removal.

Different modes of food restriction and compensatory growth in double-muscled Belgian Blue bulls: plasma metabolites and hormones

The effects of different sequences of food restriction and fattening have been studied on plasma metabolites and hormones in double-muscled Belgian Blue bulls. Twenty animals were divided into five groups. The first group (control, CG) was given,ad libitum, a fattening diet based on sugar-beet pulp. In G2 and G3, fattening was interrupted after 103 and 187 days, respectively, by a period of food restriction lasting about 2 months during which the animals received a maintenance ration. They were finished with the same diet as CG. The last two groups, G4 and G5, received a limited amount of the restriction diet to support 0·5 and 0 kg gain per day, respectively, for 4 months, before being fattened as CG. Plasma glucose, alpha-amino nitrogen, non-esterified fatty acids, urea, creatinine, thyroxine (T4), 3, 3’, 5’-tri-iodothyroxine (T3), and insulin-like growth factor-1 (IGF-1) were measured in blood samples taken every 2 weeks. Plasma GH and insulin profiles were measured in serial blood samples obtained at three different times during growth. Animals that showed compensatory growth had lower plasma urea, associated with high levels of T3, T4 and IGF–1. Animals from G2 and G3 failed to show compensatory growth. In Belgian Blue bulls, compensatory growth is markedly affected when food restriction is severe or fattening interrupted.

Swimming Speed and Swimming Metabolism of Atlantic Cod (Gadus morhua) in Relation to Available Food: A Laboratory Study

A laboratory study was performed on how young Atlantic cod (Gadus morhua) regulate their swimming speed according to available food. A circular tank 15 m in diameter was divided into six sectors, each containing two cod ranging in length from 29 to 42 cm. Live fish 5 cm long on average were used as prey. For the first 48 d food intake was changed every 1 or 2 wk equally for all six groups. During the last 31 d each group received different amounts of food. The mean swimming speed was highest (0.6 bl/s) when food intake was about half the maximum intake and lowest (0.2 bl/s) when food was unlimited or not available. Swimming metabolism was related to food intake in a similar way, but with a larger difference between the most active (50 mg O2∙kg−1∙h−1) and the least active group (10 mg O2∙kg−1∙h−1). Maximum sustained swimming metabolism was estimated to be about 0.6 times the standard metabolism. The estimated energetic cost of swimming as a percentage of energy obtained from the food decreased with food intake from 24% at maintenance ration to 2% at maximum food intake. On a log–log plot swimming speed decreased linearly with time after encounter of prey.

Effect of lupin (Lupinus angustifolius) supplementation on ovarian and pituitary activity in ewes

In each of three experiments, thirty seasonally anoestrous Border Leicester ewes were fed on a maintenance ration of oaten chaff. Fifteen of them were given a supplement of 500 g lupin grain per head per day. The ewes were treated with 10 mg follicle stimulating hormone (Expt 1), 600 I.U. pregnant mare serum gonadotrophin (Expt 2) and either 150 or 300 micrograms gonadotrophin releasing hormone (Expt 3) to determine whether the ovaries and/or the anterior pituitary were capable of responding to the nutrient status of the animals and influencing ovulation rate. In each experiment, the number and size of corpora lutea and follicles in the lupin-supplemented and -unsupplemented groups were similar. It was concluded that the mechanism by which lupins increase the ovulation rate is probably neural and not a result of direct effect on either the pituitary or the ovaries.

Effects of the infusion of amino acids into the abomasum of sheep, with emphasis on the relative value of methionine, cysteine and homocysteine for wool growth

SUMMARYMerino sheep were given abomasal infusions of various amino acids or mixtures of amino acids. Effects on wool growth were measured using autoradiography or a clipping procedure and changes in the concentration of amino acids in plasma were measured in some experiments.Mixtures of five (28 g/day) or ten (45 g/day) essential amino acids (both mixtures containing 3 g methionine) stimulated wool growth of sheep receiving a maintenance ration; on average, the volume of wool grown increased 48% and 86%, respectively. When cysteine completely replaced methionine in these mixtures, wool growth was markedly reduced, but two-thirds of the methionine could be replaced by cysteine without affecting wool growth. Homocysteine was partially effective in replacing methionine and, when supplemented with betaine, folic acid and vitamin B12, the mixture was still significantly inferior to that containing methionine. In contrast, abomasal supplements of methionine or homocysteine alone were equivalent as supplements for wool growth. The results indicated a specific role for methionine in the control of wool growth, other than the provision of cysteine. This role was postulated to be related to some function of S-adenosylmethionine.Infusion often essential amino acids caused appreciable increases in the concentrations of cystine, methionine, cystathionine and taurine in plasma; total essential amino acids increased threefold whereas nonessential amino acids decreased in concentration. The replacement of methionine in the infusion by cysteine or homocysteine significantly altered the concentration of cystine, methionine and cystathionine in plasma.Evidence was obtained that the adverse effects on wool growth of high abomasal doses of methionine (10g/day) could not be reduced or prevented by provision of additional glycine and were not related to the supposed toxic effects of 3-methylthiopropionic acid, a metabolite of the transamination pathway.

Ovarian follicular populations, steroidogenic capacity and physiological status in post-partum suckling beef cows in high and low body condition

Recent evidence indicates that body condition at calving has an important effect on the length of the post-partum anoestrous period in beef cows being longer in cows calving in low body condition (Richards et al, 1986, Wright et al, 1987). It is known that body condition affects baseline concentrations of LH (Rutter and Randel, 1984) and LH pulse frequency (Wright et al, 1987). However, the effect of body condition on ovarian follicles has not been studied.An experiment was designed to examine the effect of body condition score (BCS) at calving on follicle populations, follicular steroidogenic capacity, follicular histology and patterns of gonadotropin release at two different stages of the post-partum period (5 and 9 weeks after calving) in suckling beef cows.Thirty-eight suckling Blue-Grey cows with a mean live-weight of 567 ± 9.4 kg and mean BCS of 3.0 ± 0.05 at 110 days before calving to a synchronized insemination were differentially fed so that they achieved BCS of 2.83 ± 0.05 and 2.30 ± 0.05 for cows on a high (H) and low (L) plane of nutrition, respectively. After calving cows were fed a live-weight maintenance ration according to individual requirements. Cows of each BCS were ovariectomized at either 5 (w5) or 9 (w9) weeks after calving and follicles > 3mm in diameter were dissected from the ovaries and incubated for 2 h in culture medium (Medium 199) at 37°C. Follicles were then kept in Bouin's solution until histological examination. Follicle incubates were assayed for progesterone, testosterone and oestradiol. Blood samples were taken 2 days before ovariectomy for 10 h every 15 minutes and were later assayed for LH (all the samples) and FSH (every third sample).