Effect of inorganic selenium supplementation on selenosis in postweaning swine

A total of 72 pigs weaned at 4 wk of age were allotted by litter and weight to nine treatment groups and fed 20% protein cornsoybean meal diets supplemented with various levels of inorganic Se during a 37-d postweaning period. Eight groups were fed diets with 0, 2.5, 5.0, 7.5, 10, 15, 20 or 40 ppm Se provided as sodium selenite, while a ninth was offered the 0- and 40-ppm Se diets in separate feeders. Gains and feed intakes were similar during the trial for the 0- and 2.5-ppm Se diets. Both gain and feed intake declined as dietary Se levels above 5.0 ppm increased. At a dietary Se concentration of 40 ppm, feed consumption ceased within a few days of feeding and subsequent gains were negative. Pigs offered both the 0- and 40-ppm Se diets preferentially selected the basal as compared with the 40-ppm Se diet. When the feeders were switched at 28 d they refused the 40-ppm Se diet within a few hours. After a 17-d period, pigs fed the 20- or 40-ppm Se diet were not able to coordinate their walk, with many exhibiting an inability to stand. Alopecia was demonstrated in pigs fed 15 ppm Se or higher at 17 d, but was evident in the 5.0-ppm group at 37 d. At the termination of the trial, abnormal hoof formation at the coronary band was evident in pigs fed diets containing Se greater than or equal to 5 ppm.(ABSTRACT TRUNCATED AT 250 WORDS)     

Phenotypic measurements and various indices of lean and fat tissue development in barrows and gilts of two genetic lines from twenty to one hundred twenty-five kilograms of body weight

Two genetic lines with different lean gains were evaluated for various body measurements and indices of lean tissue in barrows and gilts from 20 to 125 kg of BW. One genetic line was identified as the low-lean line [280 g of fat-free lean (FFL)/d], and the second line was the high-lean line (375 FFL gained/d). The experiment was conducted as a completely randomized design using a 2 x 2 x 5 factorial arrangement of treatments in 6 replicates (n = 120 pigs). The 2 genetic lines and sexes were provided ad libitum access to cornsoybean mixtures that met or exceeded their required amino acid requirements for their respective lean gain potentials. Six pigs of each sex and genetic line were slaughtered initially and at 25-kg of BW intervals to 125 kg of BW. Pigs slaughtered were measured for height, width, and length using metal calipers. Backfat and LM area were measured using real-time ultrasound, with backfat depth also measured using A-mode ultrasound technology. Longissimus muscle area and back-fat thickness at the 10th rib were measured on the chilled carcass. Data was analyzed using the MIXED procedure of SAS, with the animal as the experimental unit. Shoulders (P < 0.05) and lumbars (P < 0.05) were wider in the low-lean genetic line and in barrows. Gilts and the high-lean genetic line had less backfat and greater LM areas than the low-lean genetic line. As BW increased, there was a greater increase in FFL tissue and lower backfat depths in the high-lean vs. the low-lean genetic line. This resulted in a greater divergence of measurement values as BW increased. Femur weight, length, and cortical wall thickness were greater in the high-lean genetic line, but the differences were not significant. The high-lean genetic line had a greater (P < 0.01) organic matrix content in the femur and less ash, resulting in a lower percentage of bone ash (P < 0.01). The results indicate that differences occurred phenotypically between pigs having more muscle (wider hams) or more fat (wider shoulder and lumbar). As BW increased, the high-lean pigs had an increase in lean tissue, particularly after 75 kg of BW, and less backfat and less bone mineralization, whereas the low-lean line pigs had increased backfat and greater bone mineralization. Real-time ultrasound measurements using various formulas to estimate lean tissue produced values close to those determined from carcass measurements at 100 and 125 kg of BW.     

Pod yield performance and stability of peanut genotypes under differing soil water and regional conditions

Genetic gains of cultivated peanut (Arachis hypogaea L.) have increased harvest index and disease tolerance, resulting in improved yield potential and broad-range adaptability of peanut cultivars to United States (U.S.) peanut production regions. Although this strategy has been successful, future yield increases may require peanut cultivars specifically adapted to environmental and management systems of a particular production region. Irrigation is one major management factor that varies across U.S. production regions and influences yield stability. Therefore, peanut germplasm selection for developing specifically adapted cultivars depends on knowledge of genotypic (G) pod yield responses to irrigation (M) across contrasting environmental (E) conditions (G × E × M interaction). The objectives of this 2-year study were to characterize germplasm by: (i) examining genotypic pod yield response to irrigation at locations in Florida and Texas; and (ii) estimating the genotypic pod yield performance and stability using genotype plus genotype-by-environment interaction (GGE) biplots. At the Florida location, genotypes New Mexico Valencia C (NMVC), COC 041, and Chico responded positively to increasing water application, whereas FloRun? ‘107?, C76 16, and FlavorRunner 458 responded negatively. Genotypes C76 16, ICGS 76, Chico, and ICGV 86015 had pod yields greater than the population mean. The genotype ICGS 76 had both high pod yields and stability. Pod yields of Chico were greater at the southwest locations, whereas ICGV 86015 had greater pod yields at the southeast locations. These results demonstrate a range in adaptability of distinct peanut genotypes that can be used in breeding programs for developing improved cultivars.

Abbreviations: G × E: genotype-by-environment interaction; G × E × M: genotype-by-environment-by-management interaction; G × M: genotype-by-management interaction; NMVC: New Mexico Valencia C; TWRPET: total water received as a percentage of ET_o     

Field performance in agricultural settings of a wireless temperature monitoring system based on a low-cost infrared sensor

Continuous measurement of plant canopy temperature is useful in both research and production agriculture settings. Industrial-quality infrared thermometers which are often used for measurement of canopy temperatures, while reliable, are not always cost effective. For this study a relatively low-cost, consumer-quality infrared thermometer was incorporated into a wireless monitoring system intended for use in plant physiological studies and in agricultural production settings. The field performance of this low-cost wireless system was compared to that of a typical research system based on an industrial-quality infrared thermometer. Performance was evaluated in terms of: reliability of data acquisition, quality of seasonal temperature measurements, seasonal stability of the consumer-quality infrared sensor, and the equivalence of temperatures measured by the consumer-quality and industrial-quality temperature sensors. Results indicate that for many common uses of plant temperature data, the two sensors provide functionally equivalent results. The cost savings and ease of use associated with the low-cost wireless temperature monitoring system present advantages over the higher-cost industrial-quality sensors which may make them a viable alternative in many agricultural settings.     

Cowdria ruminantium infection in ticks in the Kruger National Park.

Adult Amblyomma hebraeum ticks, the principle vector of heartwater (cowdriosis) of domestic ruminants in southern Africa, were collected in pheromone traps placed in Kruger National Park, an exclusively wildlife sanctuary in South Africa. These ticks transmitted Cowdria ruminantium, the rickettsial agent causing heartwater, to a susceptible goat, resulting in acute, fatal disease. C ruminantium was isolated in bovine endothelial cell culture from the plasma of this animal during the febrile stage of the disease and transmitted to susceptible goats, causing fatal heartwater. The prevalence of C ruminantium infection in 292 ticks was determined by polymerase chain reaction (PCR) analysis to be 1.7 per cent (95 per cent confidence interval 0.71 to 4.0 per cent). A DNA probe analysis, which is less sensitive than PCR, detected infection in three of the five PCR-positive ticks. The remaining infections were below the detection limit of the DNA probe, which is approximately 70,000 organisms. This is the first evidence that a vector-wildlife cycle of transmission of C ruminantium can be maintained independently of domestic ruminants.     

Resistance of leopard tortoises and helmeted guineafowl to Cowdria ruminantium infection (heartwater).

Experimental infection trials were conducted to investigate susceptibility of leopard tortoises (Geochelone pardalis) and helmeted guineafowl (Numida meleagris) to infection with Cowdria ruminantium, the causative agent of heartwater, a tickborne disease of domestic and wild ruminants. Ten guineafowl were inoculated intravenously with a virulent dose of C. ruminantium derived from bovine endothelial cell cultures, and four leopard tortoises were exposed to C. ruminantium infection by the feeding of infected Amblyomma hebraeum ticks. Uninfected A. hebraeum ticks (on both tortoises and guineafowl) and Amblyomma marmoreum ticks (on tortoises only) were fed on the animals during weeks 2 and 3 post-exposure in an attempt to detect infection. These ticks were analyzed for C. ruminantium infection by xenodiagnosis and with the C. ruminantium-specific pCS20 polymerase chain reaction (PCR) assay. Attempts to detect infection in ticks fed on either species were negative by both tests. These results suggest that leopard tortoises and helmeted guineafowl are refractory to C. ruminantium infection and, therefore, are unlikely to be capable of introducing heartwater directly into new areas. However, leopard tortoises are efficient hosts of A. marmoreum and A. hebraeum and are likely to be important epidemiologically in the transport and maintenance of these tick vector species.     

Effects of dietary dried whey and corn oil on weanling pig performance, fat digestibility and nitrogen utilization

Two experiments were conducted to evaluate the effects and interactions of dietary levels of corn oil (0 vs 6%) and dried whey (0 vs 25%) on performance of young pigs during a 4-wk postweaning period. The first experiment, conducted in five replicates as a 2 x 2 factorial in a randomized block design, evaluated gain and feed intakes of 172 pigs weaned at 21 d of age. Pigs were bled at weekly intervals, and samples were assayed for serum triglyceride and urea concentrations. In a second experiment, 36 barrows in three replicates were used to evaluate the same treatments on apparent digestibility and absorption of fat and N retention during each week of a 4-wk postweaning period. The dietary inclusion of dried whey resulted in greater gains and feed intakes and reduced feed-to-gain ratios during each week of the postweaning period, with the largest relative improvement occurring during wk 1. Supplemental corn oil did not enhance pig gains the first 3 wk postweaning, but response improved by wk 4. Feed intakes were slightly (P less than .10) lower when corn oil was provided. The inclusion of corn oil resulted in an improved feed-to-gain ratio (P less than .01), particularly evident during wk 3 and 4 postweaning. Neither gain nor feed utilization were improved by added corn oil during the initial 2-wk postweaning period regardless of dried whey addition. Apparent digestibilities of fat were unaffected at each weekly interval by dietary dried whey inclusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of pregnancy and lactation on the body composition of first-litter female swine

A total of 64 gilts initially weighing 120 kg were used to evaluate body composition occurring during pregnancy and lactation. All animals were fed a 14% protein corn-soybean meal diet. Eight gilts were slaughtered each at breeding, 57 and 105 d postcoitum and at 5 and 25 d postpartum, with a corresponding number of nongravid females killed at similar periods except at 5 d postpartum. Chemical composition of the empty body (ingesta-free) and maternal body (empty body minus reproductive products) was determined. Gravid gilts were heavier with larger quantities of water, protein and fat than nongravid gilts by the termination of pregnancy, but these differences were attributable to the products of conception. After the reproductive tissue components were subtracted, no indication of pregnancy anabolism was evident. Hydration in gravid swine was evident at 105 d postcoitum but was attributed to the higher water contribution from conceptus products, not maternal tissue. Maternal body fat appeared to fluctuate during gestation and lactation, whereas body protein and ash content were less affected. Both the empty body and maternal body contained approximately 83.5% protein and 16.5% ash when expressed on a fat-free dry basis, suggesting that compositional changes during reproduction largely reflect water and fat content changes in the dam's body. Carcass measurements generally reflected body compositional data.     

Efficacy of dietary D-alpha-tocopherol and DL-alpha-tocopheryl acetate for weanling pigs.

A 2 x 3 factorial experiment in a randomized complete block design was conducted using a total of 180 weanling pigs in five replicates. The study evaluated the efficacy of two dietary vitamin E sources (D-alpha-tocopherol, DL-alpha-tocopheryl acetate) added at three dietary levels (16, 48, 96 IU/kg) during a 35-d postweaning trial. Pigs within each treatment were fed two similarly fortified vitamin E diets in sequence; the first contained 40% milk products and was fed to 14 d, and the second contained 20% milk product and 5% fat and was provided from 15 to 35 d postweaning. Five pigs per pen per replicate were bled weekly for serum analysis of alpha-tocopherol, Se, cholesterol, triglyceride, and glutathione peroxidase (GSH-Px) activity. At the end of the trial, one pig per pen was randomly selected and killed with liver, loin, lung, and heart excised and frozen for tocopherol analysis. Postweaning gains, feed intakes, and efficiencies were similar between the two vitamin E sources and at the various dietary levels. Serum tocopherol concentrations were consistently higher when D-alpha-tocopherol was provided. Vitamin E sources and levels had no effect nor did they influence weekly serum Se, cholesterol, or triglyceride concentrations or GSH-Px activity. A serum and tissue interaction (P less than .05) response occurred between dietary vitamin E source x level with alpha-tocopherol concentrations increasing linearly (P less than .01) as dietary vitamin E level increased, but at a higher rate when D-alpha-tocopherol than when DL-alpha-tocopheryl acetate as fed.(ABSTRACT TRUNCATED AT 250 WORDS)