Energy sources for detritivorous fishes in the Amazon

Detritivorous fishes form an important part of the ichthyomass in the Amazon basin. Most of these fishes are contained in the orders Characiformes and Siluriformes (catfishes). The Characiformes constitute more than 30% of the total fish yield in the Amazon basin, whereas the catfishes are of minor importance. Stable isotope data indicate that Characiformes species receive most of their carbon through food chains originating with phytoplankton, while the Siluriformes receive a significant part of their energy from other plant sources.     

Internationalization of the animal science undergraduate curriculum: a survey of its current status,barriers to its implementation and its value

The goal of this project was to identify the current level at which internationalization has been adopted as a theme in the North American animal science curriculum and to identify its value and the barriers to its implementation. We surveyed animal, dairy, and poultry science departments across Canada and the United States. One hundred twenty-four surveys were mailed and 60% were returned. Associations between aspects of internationalization and student outcomes (admission to veterinary and graduate schools and starting salaries) were examined. Although administrators strongly believed internationalization had value, implementation was limited. The most common practices included international content in core animal science classes, advising, international internships, and participation of faculty in international scholarly activities. Few departments have incorporated internationalization into their mission statements or developed a specific international-themed class, scholarships devoted to international activities, or roles for international students. Few departments reported participation of students in international programs. Barriers included finances and limited commitment from higher administration. Student outcomes were positively associated with faculty size, percentage of international faculty, the ratio of international students to the total student population, international content in core animal science classes, a specific international-themed class, availability of international internships, and exchange of class material internationally via the Internet. Departments that did not offer international opportunities had a negative association (r = -0.79) with starting salary, but these relationships may not be causal. Alternatively, progressive departments may attract and retain exceptional students. The analysis indicated an awareness of the value of international programs, positive impacts in student outcomes, and financial barriers to implementation.     

Endocrine Changes after Mating in Pregnant and Non-Pregnant Llamas and Alpacas

Plasma concentrations of oestradiol-17ß, progesterone, 15-keto–dihydro–PGF_2α and luteinizing hormone (LH) were monitored in llamas and alpacas after mating with an intact male. Concentrations of LH and PGF_2α metabolite were high immediately after copulation. Ovulation occurred in 92% of the animals. The first significant increases in progesterone were recorded on day 4 after mating. In non-pregnant animals the lifespan of the corpus luteum was estimated to be 8–9 days. Luteolysis occurred in association with the release of PGF_2α. In pregnant animals, a transient decrease in progesterone concentrations was observed between days 8 and 18 in both species. No significant changes in PGF_2α secretion were registered during this period. Oes– tradiol–17ß concentrations were high on the day of mating, declined to low values on day 4, and started to increase again on day 8. Peak values after luteolysis in non-pregnant animals were significantly higher than those registered in pregnant ones. Furthermore, concentrations of oestradiol-17ß were elevated for a longer period in non–pregnant than in pregnant animals. The results suggest that progesterone from the corpus luteum exerts a negative influence on follicular activity in pregnant animals by reducing oes– tradiol-17ß secretion.     

Organic and inorganic selenium: I. Oral bioavailability in ewes

Although the essentiality of dietary Se for sheep has been known for decades, the chemical source and Se dosage for optimal health remain unclear. In the United States, the Food and Drug Administration (FDA) regulates Se supplementation, regardless of the source of Se, at 0.3 mg of Se/kg of diet (as fed), which is equivalent to 0.7 mg of Se/d or 4.9 mg of Se/wk per sheep. The objectives of this study were to evaluate the effects of Se source (inorganic vs. organic) and supplementation rate (FDA vs. supranutritional rates of 14.7 and 24.5 mg of Se/wk) on whole-blood (WB) and serum-Se concentrations. Mature ewes (n = 240) were randomly assigned to 8 treatment groups (n = 30 each) based on Se supplementation rate (4.9, 14.7, and 24.5 mg of Se?wk(-1)?sheep(-1)) and source [Na-selenite, Na-selenate (4.9 mg/wk only), and organic Se-yeast] with a no-Se control group (0 mg of Se/wk). Treatment groups were balanced for healthy and footrot-affected ewes. For 1 yr, ewes were individually dosed once weekly with 0, 4.9, 14.7, or 24.5 mg of Se, quantities equivalent to their summed daily supplementation rates. Serum- and WB-Se concentrations were measured every 3 mo in all ewes; additionally, WB-Se concentrations were measured once monthly in one-half of the ewes receiving 0 or 4.9 mg of Se/wk. Ewes receiving no Se showed a 78.8 and 58.8% decrease (P < 0.001) in WB- (250 to 53 ng/mL) and serum- (97 to 40 ng/mL) Se concentrations, respectively, over the duration of the study. Whole-blood Se decreased primarily during pregnancy (-57%; 258 to 111 ng/mL) and again during peak lactation (-44%; 109 to 61 ng/mL; P < 0.001). At 4.9 mg of Se/wk, Se-yeast (364 ng/mL, final Se concentration) was more effective than Na-selenite (269 ng/mL) at increasing WB-Se concentrations (P < 0.001). Supranutritional Se-yeast dosages increased WB-Se concentrations in a dose-dependent manner (563 ng/mL, 14.7 mg of Se/wk; 748 ng/mL, 24.5 mg of Se/wk; P < 0.001), whereas WB-Se concentrations were not different for the Na-selenite groups (350 ng/mL, 14.7 mg of Se/wk; 363 ng/mL, 24.5 mg of Se/wk) or the 4.9 mg of Se/wk Se-yeast group (364 ng/mL). In summary, the dose range whereby Se supplementation increased blood Se concentrations was more limited for inorganic Na-selenite than for organic Se-yeast. The smallest rate (FDA-recommended quantity) of organic Se supplementation was equally effective as supranutritional rates of Na-selenite supplementation in increasing WB-Se concentrations, demonstrating the greater oral bioavailability of organic Se.     

Control of Ovarian Activity in Llamas (Lama glama) with Medroxyprogesterone Acetate

Contents Progesterone and progestogens have proved to be effective in controlling follicle development and synchronization of ovarian activity in different species. In this study, vaginal sponges containing 120 mg medroxyprogesterone acetate were used to synchronize ovarian activity in llamas and to predict the time when a mature follicle will be present. Plasma concentrations of oestradiol-17β and progesterone were measured to determine follicle and corpus luteum development. The sponges were kept in the vagina for 9 days. Six days after sponge withdrawal, ovulation was induced by either GnRH injection (n = 4), mating with a vasectomized male (n = 8) or mating with an intact male (n = 10). Plasma progesterone concentrations varied between animals until day 6 after insertion of the sponges. Thereafter, progesterone levels remained close to the detection limit of the assay until ovulation was induced. The mean oestradiol-17β plasma concentration reached its lowest value 3–4 days after insertion of the sponges. Thereafter, concentrations increased and reached peak levels at day 6 after withdrawal of the sponges. All animals ovulated and developed a corpus luteum with a normal life span after the ovulatory stimulus. Blood samples were collected frequently after mating to evaluate the endocrine response to copulation. Plasma concentrations of PGF_2α metabolite and cortisol increased in parallel after copulation. The metabolite concentrations returned to basal levels 3–4 h after mating whereas the cortisol concentrations remained elevated for about 12 h after copulation The luteinizing hormone secretory pattern resembled that reported when llamas with a mature ovulatory follicle were mated. In conclusion, the protocol evaluated in this study was shown to be useful for the synchronization of ovarian activity and for predicting the time when an ovulatory follicle will be present in llamas.     

Effect of cimaterol on sheep adipose tissue lipid metabolism

Effects of dietary cimaterol (5 mg/kg) on adipose tissue metabolism of wether lambs were studied. Lipogenesis, lipolysis, fatty acid composition and adipocyte size and number were measured. Cimaterol feeding increased lipogenesis; however, this effect was not statistically significant. Insulin (1,000 microU/ml) stimulated lipogenesis of adipose tissue from control sheep. However, this elevated rate was abolished by in vitro cimaterol. Insulin had no stimulatory effect on lipogenesis in cimaterol-fed sheep. Lipolysis was depressed by cimaterol feeding. However, 10(-4) M cimaterol stimulated lipolysis in the adipose tissue from both control and cimaterol-fed sheep. Insulin inhibited stimulated lipolysis in adipose tissue from control sheep but had no effect on the stimulated lipolysis in cimaterol-fed sheep. Mean adipocyte diameter was smaller (from 74 to 70 microns) and adipocyte size distribution also was changed in the cimaterol-fed sheep. Adipocyte number per gram of tissue was not affected by cimaterol. There was a significant increase in percentage of unsaturated fatty acids in adipose tissue from cimaterol-fed sheep. These results indicate that lipogenic and lipolytic responses to insulin and cimaterol in sheep adipose tissue were altered by cimaterol feeding. The carcass fat content decrease in cimaterol-fed sheep may be attributed to the reduction in adipocyte size.     

Selection of a sterilization method for the study of cereal grain digestion

Experiments were initiated to select a sterilization method(s) that minimizes alterations in the digestive properties of cereal grains and, thus, would be suitable for the study of cereal grain digestion by pure cultures of ruminal bacteria. The following five treatments were examined: unsterilized (U), autoclaving with buffer (AB), autoclaving without buffer (AD), ethylene oxide (E), and gamma irradiation (I). Solubility of DM, starch, and CP was determined by soaking grain in buffer for 1 h followed by filtration through Whatman #54 filter paper. Ground corn and wheat from each treatment were placed in vials with a 1:1 mixture of Bryant's medium and ruminal inoculum. Vials were incubated for 4, 8, 12, 24, and 48 h and analyzed for starch content. Bacterial growth was not evident in sterilized, uninoculated samples. The AD treatment decreased the disappearance of CP in wheat and corn, whereas AB caused an increase in the disappearance of DM, CP, and starch in wheat (P less than .001) compared with U. Rates of microbial starch digestion for corn were 1.3, 1.5, 3.3, 14.7, and 3.5%/h and for wheat were 1.3, 3.4, 4.6, 17.1, and 4.6%/h for AD, E, I, AB, and U, respectively. Contrasts indicated that AD and AB differed (P less than .001) from U for both corn and wheat. It is likely that gelatinization of cereal starch enhanced microbial starch digestion in AB and the formation of Maillard products reduced starch digestion in AD. Corn and wheat sterilized with E or I had digestive properties that closely resembled those of U grain, and either sterilization method was suitable for studying cereal grain digestion.     

Effect of evening primrose oil as food supplement on reproduction in the blue fox.

Addition of evening primrose oil (EPO) to a blue fox diet in the reproduction period was evaluated in an experiment with 2 groups, each of 12 male and 25 female blue foxes, regarding the effects on reproductive performance. The experiment was carried out as a field trial and the experimental period lasted from March 10 until the end of the mating season (males) or early July (females). During this period the control group was fed the standard diet of the farm and the experimental group was fed the same diet supplemented with 4.5 g EPO and 2.5 mg zinc sulphate per animal and day. An addition of 10 mg vitamin E per 500 mg EPO was made. The results were evaluated regarding male and female treatment effects. There was an increased rate of abortions in the EPO-group, but simultaneously a non-significant decrease in the frequency of barren females, resulting in a similar level of females without litters in both groups. A tendency for increased litter size in the EPO group was found, mainly as an effect of male treatment, which might indicate an effect on semen quality.