Effect of selenium supplementation on dairy cattle.

The adequacy of current supplemental dietary selenium allowances for dairy cattle has been reviewed from the literature and by monitoring responses of dairy herds in a veterinary practice specializing in nutritional consultation. Both information sources tend to agree that a reference range of 70 to 100 ng of Se/mL of serum is an acceptable target concentration. This range can be attained most often by providing > 6 mg of supplemental Se.animal-1.d-1, but several factors affect the serum Se responses of different cows to specific Se intakes. These factors may include forage types and sources, ruminal environment, supplemental fat, dietary calcium, trace metals, and genetics. The major benefits, observed experimentally, of maintaining optimal Se intakes include minimizing the incidence of mastitis and preventing calf losses associated with myopathy and(or) respiratory disease.     

The correlation between serum selenium and blood selenium in cattle.

The selenium (Se) concentration of paired blood and serum samples from cattle was determined by 2 methods: 1) atomic absorption spectroscopy using hydride generation (HG-AAS), and 2) inductively coupled argon plasma emission spectroscopy using hydride generation (ICP). Samples from 327 cattle were analyzed by HG-AAS, and samples from 344 cattle were analyzed by ICP. The data were examined by linear regression analysis, and the technique of inverse prediction was utilized to determine prediction intervals for estimating blood Se concentration from known serum Se concentration. The correlation coefficients, by simple linear regression of serum Se on blood Se, were 0.79 (r2 = 0.62) and 0.88 (r2 = 0.77) for the HG-AAS data and the ICP data, respectively. For the HG-AAS data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. For the ICP data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. The prediction intervals were quite wide, and the accuracy of estimating blood Se from a known serum Se was not useful for diagnostic purposes. The use of serum Se concentration to assess nutritional status of cattle with respect to Se does not appear to be appropriate.     

Effects of marginal selenium deficiency and winter protein supplementation on growth, reproduction and selenium status of beef cattle

Seventy-two Hereford X Simmental cows, averaging 498 kg in body weight and 5.2 yr of age, were used in a 2-yr study to ascertain if selenium (Se)-vitamin E (E) injections and winter protein supplementation would affect growth, reproduction and health of beef cattle maintained year-round on feedstuffs marginally deficient in Se (.03 to .05 mg/kg). Cows received either no injection or a mixture of 30 mg Se (as sodium selenite) and 408 IU E injected subcutaneously beginning 3 to 4 mo prepartum and at 60-d intervals throughout the 2-yr period. Calves born to Se-E treated cows were injected with 5.5 mg Se and 75 IU E/100 kg body weight at 60-d intervals beginning at 1 mo of age. Calves were born between December 30 and February 20 and cows were bred between March 20 and May 20. Cattle grazed pasture (.05 mg Se/kg) that consisted of orchardgrass, bluegrass and white clover during the fall, spring and summer. During winter (December 15 to May 2), cattle were fed corn silage (.03 mg Se/kg) supplemented with either: no protein supplement (control), soybean meal or a urea-corn mixture. Cows and calves receiving Se-E had higher (P less than .01) whole blood glutathione peroxidase (GSH-Px) activity and plasma Se concentrations than controls. Selenium-E injections reduced (P less than .05) calf death losses from 15.3% to 4.2% and slightly increased (P less than .10) adjusted calf weaning weights. Hemoglobin concentrations were higher (P less than .05) in Se-E-injected supplemented calves at 1 mo of age but not at 5 or 7 mo of age.(ABSTRACT TRUNCATED AT 250 WORDS)     

Observations on ascites in nine cattle

Signs of ascites were observed in only nine of 1863 cattle examined over a period of five years. The ascites was most commonly associated with either primary or secondary cardiac disease; cattle with ascites have a poor prognosis because the condition is usually assocaited with terminal disease. Two animals had cor pulmonale with chronic pneumonia, three had cardiomyopathy, one had bacterial endocarditis, two had thrombosis of the caudal vena cava and one had diffuse abdominal epithelioid mesothelioma.     

Observations on Banteng cattle in Sabah

Summary Records kept between 1966 and 1971 on a herd of domesticated Banteng cattle(Bos (Bibos) banteng) in Sabah are analysed for reproductive and productive data. Birth weights (male and female respectively) were16·88 kg and15·64 kg. Growth rates for the first 6 months were0·33 kg per day (male) and0·30 kg per day (female). Age at first calving was32·37±4·76 months and calving interval12·8±2·12 months. Mortality was less than5 per cent per annum. Under conditions of nutritional stress, Banteng cattle are able to maintain body condition and high fertility (93 per cent). A timid temperament limits the utilisation of these cattle under extensive conditions.

---

Sumario Los registros mantenidos entre 1966 y 1971 en un hato de ganado Bantang domesticado (Bos (Bibos) banteng) en Saba son analizados por datos de reproducción y producción. Los pesos al nacimiento (machos y hembras respectivamente) fueron de 16,88 kg y 15,64 kg. Las tasas de crecimiento para los primeros seis meses fue de 0,33 kg por dia (macho) y 0,30 kg por dia (hembra). La edad al primer parto fue de 32,37±4,76 meses y el intervalo entre partos 12,8±2,12 meses. La mortalidad fue menor del 5 por ciento por a?o. Bajo condiciones de stress nutricional, el gandao Banteng mantiene la condición corporal y una alta fertilidad, 93 por ciento. El temperamento tímido limita la utilidad de este ganado bajo condiciones extensivas.

---

Résumé Les performance enregistrées entre 1966 et 1971 sur un troupeau de Banteng domestiques (Bos bibos banteng) à Sabah ont été examinées tant en ce qui concerne la reproduction que la productivité. A la naissance, les poids des males et celui des femelles ont respectivement été de 16,88 kg et 15,64 kg. Les gains de poids, pour les six premiers mois, ont été de 0,33 kg par jour pour les males et 0,30 kg par jour pour les femelles. L'age au premier vêlage a été de 32,37±4,76 mois et les intervalles entre vêlages de 12,8±2,12 mois. La mortalité n'a pas atteint 5 p. 100 par ans. Dans des conditions alimentaires très difficile, le bétail Banteng est apte à se maintenir en bon état, avec une haute fertilité (93 p. 100). Le tempérament craintif du Banteng fait qu'il ne peut être complètement mis à profit dans les conditions de l'élevage extensif.

     

Comparison of 3 methods of selenium assessment in cattle.

Three tests are routinely done to assess blood status of selenium in cattle: serum selenium, whole blood selenium, and glutathione peroxidase. The objective of this study was to compare the various analytical methods for determining blood selenium status in groups of mature cows and beef calves. Twenty to 30 blood samples per herd were collected from 8 beef herds in central Alberta and 1 dairy in Alberta herd twice a year from the spring of 1992 through the fall of 1995, and once from 185 spring calves in 2 beef herds in Saskatchewan. Serum and whole blood samples were submitted to 1 laboratory and whole blood samples were submitted to a 2nd laboratory. Samples for glutathione peroxidase determinations were submitted to a 3rd laboratory. Pearson's correlation coefficients and Cohen's kappa were calculated for each possible comparison among the different measures. The best agreement was observed between serum and whole blood analysis within Laboratory A. The remaining comparisons reflected poor agreement. Comparison of herd-level assessment resulted in better agreement than comparison of individual sample results among laboratories and procedures for all combinations tested. Serum selenium analysis was the only laboratory procedure for which external reference material was utilized. Serum selenium, whole blood selenium, and glutathione peroxidase measure different compartments of the blood selenium pool. The time frame of interest, supplementation practices, and the stability of recent dietary intake determine the optimum assessment method for individual animals or herds. Determination of the serum status or of blood selenium is more consistently measured at the herd-level than for individual samples.     

Effects of selenium supplementation in cattle on aquatic ecosystems in northern California.

The potential impact on aquatic ecosystems of supplementing the diets of beef cattle with selenium (Se) was studied on 4 northern California ranches. All study sites included an area of concentrated use by cattle that had diets supplemented with Se. In each case, a stream flowed through the site and provided a control sampling area upstream and a treated sampling area downstream. Specimens of water, sediment, algae, aquatic plants, aquatic invertebrates, and fish were analyzed fluorometrically for total Se content. Significant differences in Se concentration were not found between specimens from upstream control areas and those from downstream areas subjected to use by Se-treated cattle. Evidence was not found that Se supplementation in cattle at maximal permitted concentrations caused Se accumulation in associated aquatic ecosystems.     

Thyroid hormone concentrations in selenium deficient and selenium sufficient cattle

Selenium deficient calves when compared to selenium supplemented calves had increased plasma thyroxine concentrations and decreased plasma tri-iodothyronine concentrations. These changes in the selenium deficient calves were accompanied by significant increases in plasma urea and creatinine concentrations and decreased plasma alkaline phosphatase activity. The demonstration that low selenium status can cause imbalances in thyroid hormone metabolism may provide an explanation for some of the effects of the deficiency.     

Observations on the numbers of the tickRhipicephalus appendiculatus on the ears of Zebu cattle in relation to hierarchical status in the herd

Summary A herd of21 East African Zebu cattle was observed when leaving a holding paddock and subsequently whilst grazing. The ranking positions of each animal in the herd over three periods during the dry season were ascertained. Frequent collections were also made of the adultRhipicephalus appendiculatus attached to the ears. It was shown that animals which tended to be at the front of the herd carried most ticks and therefore an animal's hierarchical position in the herd influenced the number of ticks which attached to it.This work was done whilst R.M.N. and T.E.F. were serving as Animal Health Officers with the Food and Agricultural Organization of the United Nations in a Government project for the improvement of tick control methods in Tanzania, supported by the United Nations Development Programme.     

Effect of selenium supplementation and source on the selenium status of horses

This study was conducted to determine the effect of Se supplementation and source on the Se status of horses. Eighteen 18-mo-old nonexercised horses were randomly assigned within sex to 1 of 3 treatments: 1) control (CTRL, no supplemental Se, 0.15 mg of Se/kg of total diet DM); 2) inorganic Se (INORG, CTRL + 0.45 mg of Se/kg of total diet DM from NaSeO3); or organic Se [ORG, CTRL + 0.45 mg of Se/kg of total diet DM from zinc-L-selenomethionine (Availa Se, Zinpro, Corp., Eden Prairie, MN)]. Horses were acclimated to the CTRL diet (7.1 kg of DM alfalfa hay and 1.2 kg of DM concentrate per horse daily) for 28 d. After the acclimation period, the appropriate treatment was top-dressed on the individually fed concentrate for 56 d. Jugular venous blood samples were collected on d 0, 28, and 56. Middle gluteal muscle biopsies were collected on d 0 and 56. Muscle and plasma were analyzed for Se concentrations. Glutathione peroxidase activity was measured in muscle (M GPx-1), plasma (P GPx-3), and red blood cells (RBC GPx-1). Data were analyzed as a repeated measures design. Mean plasma Se concentration on d 28 and 56 was greater (P < 0.05) for Se-supplemented horses compared with CTRL horses, and tended (P < 0.1) to be greater in ORG vs. INORG on d 28. Mean muscle Se concentration and P GPx-3 activities increased (P < 0.05) from d 0 to 56 but were not affected by treatment. Mean RBC GPx-1 activity tended to be greater (P < 0.1) in ORG than INORG or CTRL horses on d 28, and tended to be greater (P < 0.1) for INORG compared with ORG horses on d 56. Mean RBC GPx-1 activity of INORG and ORG horses was not different from that of CTRL on d 56. Mean M GPx-1 activity decreased (P < 0.01) from d 0 to 56. In conclusion, zinc-L-selenomethionine was more effective than NaSeO3 at increasing plasma Se concentration from d 0 to 28; however, both supplemental Se sources had a similar effect by d 56. No difference in Se status due to Se supplementation or source could be detected over a 56-d supplementation period by monitoring middle gluteal muscle Se, M GPx-1, or P GPx-3. Results for RBC GPx-1 also were inconclusive relative to the effect of Se supplementation and source.