采食含高硫、钼日粮的肉牛对甘氨酸铜中铜的生物利用率

选择60头平均9月龄、初始体重为277kg的肉牛,饲喂含高硫（S）和钼（Mo）日粮,进行148d试验,测定甘氨酸铜（CuGly）相对饲料级硫酸铜（CuSO4）的生物利用率。肉牛包括29头安格斯牛,31头安格斯与西门塔尔杂交牛,按体重随机分配到5个处理组中,分别为：①对照组（不添加铜）;②含铜5mg·kg^-1干物质,以硫酸铜形式添加;③含铜10mg·kg^-1干物质,以硫酸铜形式添加;④含铜5mg·kg^-1干物质,以甘氨酸铜形式添加;⑤含铜10mg·kg^-1干物质,以甘氨酸铜形式添加。肉牛以玉米青贮饲料为基础日粮（含铜8.2mg·kg^-1干物质）,采用单栏饲喂。阶段1,在肉牛日粮中添加钼2mg·kg^-1干物质、硫0.15%,持续120d;随后,在阶段2肉牛日粮中添加钼6mg·kg^-1干物质、硫0.15%,持续28d。添加硫酸铜和甘氨酸铜都能极显著改善平均日增重和增重饲料比（P=0.01）。与对照组相比,添加铜组试验结束时肉牛血浆铜蓝蛋白,血浆铜和肝脏铜值显著提高（P〈0.05）。与处理②和④组肉牛相比,处理③和⑤组肉牛血浆铜、肝脏铜和血浆铜蓝蛋白值显著升高（P〈0.05）。阶段1,根据结束时血浆铜、肝脏铜和血浆铜蓝蛋白值做多元线性回归,甘氨酸铜中铜相对硫酸铜（100%）的生物学利用率分别为140%（P=0.10）,131%（P=0.12）和140%（P=0.01）。阶段2,添加钼6mg·kg^-1干物质后,与硫酸铜中铜相比,甘氨酸铜中铜的相对生物学利用率极显著升高（P=0.01）,根据血浆铜、肝脏铜和血浆铜蓝蛋白值,分别为144%,150%和157%。试验结果显示,与硫酸铜相比,高硫、钼日粮中甘氨酸铜中的铜更有效。     

Investigating the Research Practices of Agriculture Scholars: Findings From the University of Florida

ABSTRACT

The University of Florida (UF) George A. Smathers Libraries is one of 19 institutions that participated in an Ithaka S+R Research Support Services investigation of agricultural sciences. The authors conducted a qualitative analysis of research support services based on one-on-one semistructured interviews with 15 faculty of the UF Institute of Food and Agricultural Sciences in 2016. A number of core themes emerged from the analysis of research practices in the local study at UF. Core themes included finding appropriate literature, data management issues and tools, repositories for sharing research products, and research dissemination. This report summarizes a subset of these results, focusing on themes related to academic library services that support agricultural scholars research needs.     

Sensitivity of boreal forest carbon balance to soil thaw

We used eddy covariance; gas-exchange chambers; radiocarbon analysis; wood, moss, and soil inventories; and laboratory incubations to measure the carbon balance of a 120-year-old black spruce forest in Manitoba, Canada. The site lost 0.3 +/- 0.5 metric ton of carbon per hectare per year (ton C ha-1 year-1) from 1994 to 1997, with a gain of 0.6 +/- 0.2 ton C ha-1 year-1 in moss and wood offset by a loss of 0.8 +/- 0.5 ton C ha-1 year-1 from the soil. The soil remained frozen most of the year, and the decomposition of organic matter in the soil increased 10-fold upon thawing. The stability of the soil carbon pool ( approximately 150 tons C ha-1) appears sensitive to the depth and duration of thaw, and climatic changes that promote thaw are likely to cause a net efflux of carbon dioxide from the site.     

Performance, carcass characteristics, and lipid metabolism in growing and finishing Simmental steers fed varying concentrations of copper.

An experiment was conducted to determine the effects of dietary copper (Cu) on performance, carcass characteristics, and lipid metabolism in Simmental steers. Thirty-six Simmental steers (329.3 +/-11.4 kg) were stratified by weight and randomly assigned to treatments. Treatments consisted of the following: control (no supplemental Cu) and 10 or 40 mg Cu/kg DM from Cu sulfate. Each treatment consisted of six replicate pens, with each pen containing two steers. A corn silage-soybean meal-based diet was fed for 56 d. Steers were then switched to a high concentrate diet. Performance was not affected by treatment during the growing or finishing phases. Plasma Cu concentrations were higher (P < 0.05) in steers receiving supplemental Cu by d 56 of the growing phase and remained higher (P < 0.05) at all 28-d sampling periods during the finishing phase. Liver Cu concentrations were higher (P < 0.001) in steers receiving supplemental Cu at the end of the growing phase and on d 84 and at the end of the finishing phase. Steers supplemented with 40 mg Cu had higher (P < 0.001) liver Cu concentrations than those supplemented with 10 mg Cu/kg DM. Serum and longissimus muscle cholesterol concentrations were similar between treatments. Longissimus muscle and backfat fatty acid composition was similar between treatments. These results indicate that Cu supplementation given to Simmental steers increased Cu status but had no effect on performance, carcass characteristics, or lipid or cholesterol metabolism.     

Effects of zinc methionine and zinc oxide on performance, blood characteristics, and antibody titer response to viral vaccination in stressed feeder calves.

Ninety steers with an average weight of 214 kg were purchased at 2 feeder calf sales and transported 70 to 100 km. On arrival at the feedlot, steers were weighed and identified, blood was withdrawn, and the steers were vaccinated against bovine herpesvirus-1 (BHV-1) and parainfluenza3 (PI3), using a modified live vaccine, and randomly assigned to treatment groups. Treatments were: control (no supplemental zinc; zinc methionine; and zinc oxide. The control diet contained 26 mg of zinc/kg diet, and zinc was added in treatments 2 and 3 to provide 25 mg of supplemental zinc/kg diet. Neutralizing antibody titers were determined on serum samples taken on days 0 and 14 as a measure of the immune response to BHV-1 and PI3 vaccination. Weight gains for the 28-day study were similar across treatments. Dry matter intake tended to be higher in steers fed supplemental zinc from either source, because steers fed zinc methionine and zinc oxide consumed 5.2 and 4.4% more feed, respectively, than controls. Antibody titers against BHV-1 tended to be higher in steers supplemented with zinc methionine on day 14. Differences between treatments were not found for PI3 titers. Mortalities did not occur and morbidity rate was low.     

Comparison of tiletamine-zolazepam-ketamine and tiletamine-zolazepam-ketamine-xylazine anaesthesia in sheep

Summary The anaesthetic effects of intravenous tiletamine-zolazepam 6.6 mg/kg-ketamine 6.6 mg/kg (TK) and tiletamine-zolazepam 6.6 mg/kg-ketamine 6.6 mg/kg-xylazine 0.11 mg/kg (TKX) were evaluated in six wethers. Heart rate, respiration rate, arterial blood pressure, and the electrocardiogram were monitored during anaesthesia. Analgesia was tested by electrical stimulation in the left flank. Atropine (0.03 mg/kg) was given intramuscularly before induction, but after recording of baseline heart rate and respiratory rate. The duration of analgesia was 28.7 ± 6.9 min with TK and 82.8 ± 26.6 min with TKX. Heart rate increased significantly within 5 min after TK or TKX administration. Respiratory rate remained unchanged after TK administration, but increased significantly from 5 to 45 min after TKX administration. Arterial blood pressure decreased significantly at 15 min with TK and 30 min with TKX. Sheep remained recumbent for 201 min with TK and 166 min with TKX. All recovered uneventfully. We conclude that either TK or TKX may be used for anaesthetising sheep.     

Maturation Status, Protein Synthesis and Developmental Competence of Oocytes Derived from Lambs and Ewes

The efficacy of oocyte selection for in vitro embryo production depends on the abundance and diameter of follicles, cumulus layers around the oocytes and subsequent fertilization. Application of `ovum pick-up' technique allows us to utilize partially matured oocytes for embryo production even from juvenile subjects. To compare their developmental competence, oocytes derived from lambs and ewes and cultured in maturation medium for up to 26 h were assessed at 2 h intervals by confocal microscopy after chromatin and microtubulin-specific fluorochrome labelling. Lamb oocytes reached second meiotic metaphase (MII) at lower numbers at 24 h (60.0%) and 26 h (28.6%) whereas 85.7% of adult-derived oocytes attained MII status by 24 h of maturation. Radiolabelling of oocyte proteins revealed higher incorporation of [³⁵S-]-methionine and [³⁵S]-cysteine in adult-derived oocytes compared to lamb oocytes. Although the cleavage rate of lamb oocytes was similar to that of ewe oocytes, the proportion reaching blastocyst stage was significantly lower (p < 0.05) in the lamb-derived oocytes. However, blastocysts from both types of oocytes displayed similar cell lineage allocations to inner cell mass and trophectoderm.     

The efficacy of a controlled-release albendazole capsule in suppressing nematode burdens in sheep

An experiment was undertaken between July and November 1985 in East Gippsland, Victoria, to determine the efficacy of an intra-ruminal controlled-release albendazole capsule against naturally acquired worm burdens and larval challenge in Merino hoggets. Two groups of 20 sheep, one group untreated, the other dosed with a capsule were grazed together; 5 sheep from each group were slaughtered for total worm counts 30 and 101 d after capsules were administered. Serum anthelmintic concentrations, faecal egg counts and body weights were monitored. Most capsules were exhausted within 91 d of administration. During the estimated 80 d for which they remained active the capsules were highly effective against the benzimidazole-susceptible worm populations. Faecal egg counts were reduced to zero and total worm populations were reduced by over 97% 30 d after administration. By 101 d egg counts were increasing and worm counts indicated that sheep were becoming reinfected. Sheep treated with the capsules grew faster than those not treated.