Retrospective study of 103 presumed cases of tick (Ixodes holocyclus) envenomation in the horse

Objective Review 103 cases of presumed tick envenomation in horses. Design Retrospective study. Method Variables, including date of presentation, age, breed, weight, presence of ticks, gait and respiration scores, duration of recumbency, treatment, outcome and complications were recorded. A series of univariable screening tests were performed and used in a multivariable logistic regression model. Results There were a total of 103 cases affecting 10 breeds, aged between 1 week and 18 years of age. Horses >6 months old and weighing >100 kg had a higher odds of death than those <6 months old and <100 kg. Cases were seen from North Queensland to the central coast of New South Wales and were more likely to present in the warmer months. There was no association between the number of ticks found on an animal and death. Horses with a higher respiratory score had higher odds of dying, but there was no association between gait score and survival. Horses recumbent >120 h after presentation had higher odds of dying. Complications were reported in 35% of horses. The odds ratio for survival was higher for horses receiving >0.5 mL/kg of tick antiserum. Overall, 74% of horses survived. Multivariable modelling was limited by the small sample size. Conclusion In general, tick envenomation in horses follows the geographic distribution of Ixodes holocyclus. Tick antiserum administered at >0.5 mL/kg increases the odds of survival. It would appear that the complications associated with managing a recumbent horse increase the odds of death.     

Antibody prevalence of low-pathogenicity avian influenza and evaluation of management practices in Minnesota backyard poultry flocks

Low‐pathogenicity avian influenza (LPAI) viruses have caused illness in poultry and humans with poultry contact. To determine whether there is evidence of exposure to avian influenza viruses (AIV) among backyard poultry in Minnesota and their human caretakers, 150 flocks of backyard birds were sampled for antibodies to AIV from August 2007 through December 2008. One hundred flocks were tested through routine slaughter surveillance by the Minnesota Board of Animal Health and an additional 50 flocks were contacted and sampled by study investigators. Blood was collected from 10 to 13 birds from each flock and a survey of biosecurity and management practices was administered to the flock owner. Blood samples were tested by agar gel immunodiffusion (AGID) for influenza A antibodies. Tested flocks had a median flock size of 100 birds (range: 12–800 birds), and were most commonly owned for meat for personal use (81% of respondents), fun or hobby (58%) and eggs for personal use (56%). Although 7% of flock owners reported that their birds had shown respiratory signs in the previous 3 months, only 1 of 150 flocks tested positive for influenza by AGID. Antibodies to LPAI H6N1 were detected in the positive flock. The owner of the positive flock did not have antibodies to H6 or other common AIV. Based on the findings of this study, the risk of transmission of LPAI viruses from backyard poultry to owners in Minnesota appears to be low under current conditions and management practices.     

Glucose and insulin responses to different dietary energy sources in Thoroughbred broodmares grazing cool season pasture

The objectives of this study were to characterize the glycemic and insulinemic responses of Thoroughbred broodmares fed late spring pasture only or a mixture of pasture and a high starch or low starch feed and to test hypotheses about differences in the glycemic and insulinemic effects of these dietary regimes. A group of 15 mares were divided into three treatment groups; pasture and high starch feed (PHS), pasture and low starch feed (PLS), and pasture only (PO) and maintained in these groups for 4.5 months prior to this study. These groups were maintained on a single pasture that was temporarily divided into three sections. The study protocol was conducted over two days. On day 1 the mares were fed their respective treatments and on day 2 all mares were allowed access to pasture only. On both days plasma glucose and insulin were measured in samples taken over a 7.5 h period. Baseline measurements for glucose and insulin were not different between any of the treatment groups on either day (P > 0.05). The baseline insulin concentrations of these pasture-kept mares (26.7 ± 8.3 mIU/L) were high compared to those reported from stall-kept horses. Plasma glucose and insulin on day 1 were influenced by treatment group, sample time, and an interaction between treatment and time (P < 0.05). On day 2 there was no significant influence of treatment group (P > 0.05). Glucose and insulin rose to higher (P < 0.01) peak concentrations in the PHS group on day 1 when compared to the PLS and PO groups, with no difference (P > 0.05) detected between the PLS and PO groups. These results are reflected in greater areas under the concentration-time curves for glucose and insulin in the PHS group on day 1 (P < 0.05). On day 2 there were no differences in any of the glucose and insulin characteristics for any of the treatment groups (P > 0.05). These results indicate a clear difference in the glycemic and insulinemic effect of the PHS feed compared to the PLS and PO groups. Of further interest are the glucose and insulin characteristics of these pasture-kept mares that indicate a low insulin sensitivity and high insulin secretory response. This study provides further information on factors influencing glycemic and insulinemic responses in horses.     

Comparing the 2000 and 2005 factors affecting the selling price of feeder cattle sold at Arkansas livestock auctions

The objectives of the study were to determine how factors affecting the selling price of feeder calves changed from 2000 to 2005 and to examine the perception that discounts narrow or even disappear as calf supplies decrease and selling prices increase. Data from weekly Arkansas livestock auctions were collected from January 1 to December 31 in 2000 and 2005. Data included calf sex, breed type, color, muscle score, horn status, frame score, fill, condition, health, and BW. Mean selling prices for 2000 and 2005 were $92.91 +/- 15.05 and $118.32 +/- 15.13 (mean +/- SD; $/45.45 kg), respectively. Individual price observations were subtracted from the respective annual means and became the dependent variable. The selling prices for feeder calves sold in groups of 2 to 5 calves and in groups of >/= 6 calves were greater in 2005 than 2000 (P < 0.001). Steers received a greater premium ($6.48 +/- 0.09 vs. $6.02 +/- 0.08; mean +/- SE) and bull calves received greater discounts ($0.30 +/- 0.14 vs. $1.68 +/- 0.09) in 2005 than in 2000. Breeds types that increased in value from 2000 to 2005 were Angus x Hereford, Angus, Angus x Charolais, and Brahman (P < 0.001). Breed types that received a reduced selling price in 2005 compared with 2000 (P < 0.001) were one-fourth Brahman Cross, Charolais, Charolais x Limousin, Hereford x Limousin, Limousin, Limousin x one-fourth Brahman, Longhorn, Saler and Simmental. Yellow-white face, black-white face, black, and gray feeder calves received an increase in selling price from 2000 to 2005 (P < 0.001). Although fewer horned feeder calves were sold in 2005 (P < 0.01), they received greater discounts in 2005 than 2000 (-$2.86 +/- 0.16 and -$0.51 +/- 0.09; P < 0.001). In 2005, large-framed feeder calves did not receive the premium detected in 2000, but medium-framed feeder calves in 2005 received a greater selling price compared with 2000. Feeder calves with a muscle score of 1 received a greater premium in 2005 compared with 2000 ($2.58 +/- 0.06 and $0.02 +/- 0.09, respectively; P < 0.001). Feeder calves with a muscle score of 2 were discounted in both years, but the discount in 2005 was not as great as in 2000 (P < 0.001). Full and tanked feeder calves received greater discounts in 2005 than in 2000 (P < 0.001). Discounts for fleshy and fat feeder calves were greater in 2005 than in 2000. Most factors affecting the selling price of Arkansas feeder calves in 2000 affected the selling price in 2005. Although feeder calf supplies were smaller in 2005 than 2000, many discounts increased.     

Effects of source of supplemental zinc on performance and humoral immunity in beef heifers

Two experiments were conducted to evaluate receiving-period performance, morbidity, and humoral immune response, as well as finishing performance and carcass characteristics of heifers fed different sources of supplemental Zn. In Exp. 1, 97 crossbred beef heifers (initial BW = 223.4 kg) were fed a 65% concentrate diet with no supplemental Zn (control) or 75 mg of supplemental Zn/kg of DM from Zn sulfate, Zn methionine, or Zn propionate. During a 35-d receiving period, heifers were monitored daily for signs of bovine respiratory disease. Serum samples were collected for Zn analysis on d 0, 14, and 28. After the receiving period, heifers were adapted to and fed a high-concentrate diet with no supplemental Zn for 42 d. Heifers were then assigned to finishing diet treatments, with the same concentrations and sources of supplemental Zn as during the receiving period and fed for an average of 168 d. Serum samples also were obtained on d 0 and 56 of the finishing period and at the end of the study. During the receiving period, control heifers had a greater (P < or = 0.05) BW and G:F on d 35 than heifers in the other treatments, but no differences were observed among treatments for morbidity or serum Zn concentrations (P > or = 0.50). For the finishing period, DMI and ADG did not differ among treatments; however, overall G:F tended (P = 0.06) to be less for control heifers than for heifers in the 3 supplemental Zn treatments. On d 56 of the finishing period, control heifers tended (P = 0.06) to have a lower serum Zn concentration than heifers in the 3 supplemental Zn treatments. In Exp. 2, 24 crossbred beef heifers (initial BW = 291.1 kg) were fed the same 4 treatments as in Exp. 1 for a 21-d period. The humoral immune response to treatments was determined by measuring specific antibody titers after s.c. injection of ovalbumin on d 0 and 14. Body weights and blood samples for serum Zn concentration and ovalbumin IgG titers were collected on d 0, 7, 14, and 21. Serum Zn concentration and specific ovalbumin IgG titers did not differ (P > 0.10) among the 4 treatments on any sampling day. Results from these 2 studies showed no major differences among the sources of supplemental Zn for receiving period morbidity, ADG, DMI, and humoral immune response of beef heifers; however, a lack of supplemental Zn during an extended finishing period tended to negatively affect G:F.     

Effect of previous locoweed (Astragalus and Oxytropis species) intoxication on conditioned taste aversions in horses and sheep

Locoweed species (Astragalus and Oxytropis spp.) are a serious toxic plant problem for grazing livestock. Horses and sheep have been conditioned to avoid eating locoweed using the aversive agent LiCl. The objective of this study was to determine if previous locoweed intoxication affects food aversion learning in horses and sheep. Horses and sheep were divided into 3 treatment groups: control (not fed locoweed and not averted to a novel feed); locoweed-novel feed averted (fed locoweed and averted to a novel feed); and averted (not fed locoweed and averted to a novel feed). Animals in the locoweed-novel feed averted groups were fed locoweed during 2 periods of 21 and 14 d, respectively, with each feeding period followed by a 14-d recovery period. Animals were averted to a novel test feed at the end of the first locoweed-feeding period, and periodically evaluated for the strength and persistence of the aversion. During the first recovery period, locoweed-novel feed averted horses ate less (9.5% of amount offered) of the test feed than did control horses (99.8%) and did not generally differ from averted horses (0%). During recovery period 2, locoweed-novel feed averted horses (4.3%) differed (P = 0.001) in consumption (% of offered) of the test feed from controls (100%) and the averted group (0%). Locoweed-novel feed averted sheep differed (P = 0.001) from controls (14.4 vs. 99.5%, respectively, during recovery period 1), whereas locoweed-novel feed averted sheep did not differ (P > 0.50) from averted sheep (0.6%). During the second recovery period, control sheep (100%) differed (P < 0.05) from averted (0%) and locoweed-novel feed averted (12.2%) groups. Two intoxicated sheep (locoweed-novel feed averted) partially extinguished the aversion during the first recovery period, but an additional dose of LiCl restored the aversion. Two of 3 intoxicated horses had strong aversions that persisted without extinction; 1 horse in the locoweed-novel feed averted group had a weaker aversion. These findings suggest that horses and sheep previously intoxicated by locoweeds can form strong and persistent aversions to a novel feed, but in some animals, those aversions may not be as strong as in animals that were never intoxicated.     

Cattle selected for lower residual feed intake have reduced daily methane production

Seventy-six Angus steers chosen from breeding lines divergently selected for residual feed intake (RFI) were studied to quantify the relationship between RFI and the daily rate of methane production (MPR). A 70-d feeding test using a barley-based ration was conducted in which the voluntary DMI, feeding characteristics, and BW of steers were monitored. The estimated breeding value (EBV) for RFI (RFI(EBV)) for each steer had been calculated from 70-d RFI tests conducted on its parents. Methane production rate (g/d) was measured on each steer using SF(6) as a tracer gas in a series of 10-d measurement periods. Daily DMI of steers was lower during the methane measurement period than when methane was not being measured (11.18 vs. 11.88 kg; P = 0.001). A significant relationship existed between MPR and RFI when RFI (RFI(15d)) was estimated over the 15 d when steers were harnessed for methane collection (MPR = 13.3 x RFI(15d) + 179; r(2) = 0.12; P = 0.01). Animals expressing lower RFI had lower daily MPR. The relationship established between MPR and RFI(15d) was used to calculate a reduction in daily methane emission of 13.38 g accompanied a 1 kg/d reduction in RFI(EBV) in cattle consuming ad libitum a diet of 12.1 MJ of ME/kg. The magnitude of this emission reduction was between that predicted on the basis of intake reduction alone (18 g x d(-1) x kg of DMI(-1)) and that predicted by a model incorporating steer midtest BW and level of intake relative to maintenance (5 g x d(-1) x kg of DMI(-1)). Comparison of data from steers exhibiting the greatest (n = 10) and lowest (n = 10) RFI(15d) showed the low RFI(15d) group to not only have lower MPR (P = 0.017) but also reduced methane cost of growth (by 41.2 g of CH(4)/kg of ADG; P = 0.09). Although the opportunity to abate livestock MPR by selection against RFI seems great, RFI explained only a small proportion of the observed variation in MPR. A genotype x nutrition interaction can be anticipated, and the MPR:RFI(EBV) relationship will need to be defined over a range of diet types to account for this.     

Temporal changes in circulating levels of plasma interleukin-8 during peripartum period in Murrah buffaloes (Bubalus bubalis) under subtropical climate

The objective of this study was to elucidate the changes in circulating levels of plasma interleukin-8 (IL-8) during peripartum period in Murrah buffaloes (Bubalus bubalis). IL-8 was estimated in blood plasma of healthy peripartum Murrah buffaloes (n = 6) on days ±30, ±15, ±5, ±3, ±1 and 0 pre- and postpartum with respect to the day of parturition (day 0) in each of the two different seasons (hot–humid and spring). The mean microclimate Temperature–Humidity Index (THI) during spring season was significantly lower (p < 0.01) than the corresponding THI in hot–humid season. In both the seasons, plasma IL-8 remained lower in prepartum period (≤46.56 ± 14.08 pg/ml during spring and ≤ 73.18 ± 18.56 pg/ml during hot–humid season) than in the postpartum period (≥51.41 ± 13.82 pg/ml during spring and ≥ 84.13 ± 16.97 pg/ml in hot humid season). During spring, the IL-8 levels were significantly higher (P < 0.05) on days +5 and +15 postpartum in comparison to the IL-8 levels on days −30, −5, and −3 prepartum. During hot–humid season, IL-8 level was significantly higher (P < 0.05) on day +30 as compared to the IL-8 levels on days −30 and −5 prepartum. The correlation between IL-8 and mean microclimate THI was significant (r = 0.25, P < 0.01). From the results, it is concluded that peripartum period in buffaloes is associated with an inflammatory response leading to significantly higher plasma IL-8 during parturition and postpartum period than in the pre-partum period.     

多糖和寡糖的体外发酵特性及其对鸡盲肠微生物菌群的影响

本研究采用体外累积发酵产气法和16SrDNA指纹图谱鉴定技术研究了来自香菇、银耳和黄芪的天然免疫活性多糖(LenE,TreE和AstE)及酵母胞壁甘露寡糖(MOS)对鸡肠道微生物菌群及其发酵特性的影响。结果表明,三种多糖提取物的总糖含量均占干物质的60%以上,而MOS总糖含量在90%以上。多糖和寡糖具有不同的发酵模式;MOS、AstE和LenE三种糖的发酵模式相似,呈一阶段发酵模式;TreE呈两阶段的发酵模式。三种糖中,MOS和AstE发酵速度较TreE快。MOS和AstE在发酵后总VFA产量最高,pH最低;黄芪多糖发酵后产生较多的直链脂肪酸和较低的氨。这些多糖和寡糖提取物影响肠道微生物的活性和组成成分,体现在发酵模式和发酵终产物的显著改变上。以上研究结果表明,来自香菇、银耳和黄芪的天然免疫活性多糖(LenE,TreE和AstE)及酵母胞壁甘露寡糖(MOS)在体外发酵后,均具有显著改变鸡盲肠微生物发酵终产物的含量和盲肠微生物活性的作用。