Mortality attributed to respiratory problems among finisher pigs in the United States

In the 1995 National Swine Study of the United States National Animal Health Monitoring System, producers identified respiratory problems as the leading cause of death in pigs during the grower/finisher phase of production. Over a six-month period, 61.7±4.1% (mean±SEM) of operations reported at least one death attributed to respiratory problems among finisher pigs (based on 388 operations representing operations with ≥300 finisher pigs in 16 states). Mean mortality attributed to respiratory problems was 0.9±0.1% of finisher pigs per operation. Stepwise logistic regression (using SAS) was used to identify factors associated with operations attributing at least one death to respiratory problems, and to identify factors associated with reporting ≥2% mortality attributed to respiratory problems. Final models were run with SUDAAN to account for the sampling strategy. Attributing at least one death to respiratory problems was associated with having ≥3000 pigs enter the grower/finisher unit over a six-month period; diagnosis of Haemophilus (or Actinobacillus) in the past 12 months; and keeping pigs in the grower/finisher unit >120 days (as compared to <100 days). Not having a farrowing facility, mean weaning age <28 days, and <50% of finisher pigs on solid concrete only were associated with reporting ≥2% mortality attributed to respiratory problems.     

Survey of small-enterprise chicken operations in the United States

The National Animal Health Monitoring System (NAHMS) Small-Enterprise Chicken study was conducted to better understand bird movement and biosecurity practices of commercial poultry operations having fewer than 20,000 chickens. A stratified random sample of 2511 operations having 1000–19,999 chickens was selected from a list maintained by the National Agricultural Statistics Service (NASS), based primarily upon data from the 2002 Census of Agriculture; 1789 (72.1%) operations participated in the study. Over one-half of operations were contract operations with breeding birds, and one-fourth were contract operations without breeding birds. Only 17% of operations were independent (noncontract) operations. Independent operations were primarily table-egg producers and to a lesser extent, growers. Independent operations were more likely to have birds other than chickens, to allow outdoor access to birds, and had less stringent biosecurity requirements compared to contract operations.     

Prevalence of species and genotypes of Cryptosporidium found in 1-2-year-old dairy cattle in the eastern United States

The prevalence of Cryptosporidium species in 1-2-year-old heifers was determined for 571 animals on 14 dairy farms in seven states on the East Coast of the United States. A fecal specimen collected directly from each heifer was processed to concentrate oocysts that were then examined by polymerase chain reaction (PCR). For every PCR-positive specimen the 18S rRNA gene of Cryptosporidium was sequenced. Cryptosporidium was identified by PCR from heifers on 13 of 14 farms. On all except four farms groups of heifers were housed in a barn or in large covered pens. Others were pastured. From many of the same farms an earlier study reported that 41% of 393 pre-weaned calves and 26.2% of 447 post-weaned calves were infected. In the present study, 11.9% of 571 heifers were infected with Cryptosporidium, 0.7% with Cryptosporidium parvum, the zoonotic species. Of 68 PCR-positive specimens characterized by gene sequencing 1, 4, 10, 24, and 29 calves were infected with Cryptosporidium suis, Cryptosporidium parvum, Cryptosporidium deer-like genotype, Cryptosporidium bovis, and Cryptosporidium andersoni, respectively. These findings demonstrate a lower prevalence of infection in 1-2-year-old dairy cattle than in younger cattle as well as a change in the diversity of species present. Consequently, the risk of humans acquiring infection with C. parvum from exposure to feces from yearling and older cattle appears much lower than from exposure to pre-weaned calves.     

Relationship between the timing of insemination based on estrus detected by the automatic activity monitoring system and conception rates using sex-sorted semen in Holstein dairy cattle

We investigated the optimal timing of artificial insemination (AI) for achieving pregnancy according to the onset/end of estrus detected by an accelerometer system in Holstein cattle. The conception rates of conventional semen were used as a reference. The conception rate from AI of sex-sorted semen was higher at −4 to 4 h (57.1%) from the end of estrus than those at −12 to −4 h (37.7%) and 12–20 h (30.3%), whereas AI at 4–12 h showed an intermediate conception rate (47.4%). Conversely, conception rates were similar in AI performed between 0 and 32 h from the onset of estrus. Regarding conventional semen, the interval from the onset and end of estrus did not affect conception rates. The present results suggest that the time of the end of estrus is the better indicator of optimal AI timing for sex-sorted semen than the onset of estrus.     

施氮对不同定植年限臂形草草场产量与质量的影响

对云南省南亚热带湿热地区的思茅曼中田畜牧场臂形草草场不同定植年限中每年施氮素与否对草场的产草量及养分含量的影响进行了调查和统计分析。结果表明：通过每年施氮肥，能明显地提高全草场的产量和质量，如以１９８６年（１２０）＊与１９８６（０）＊两不同处理在定植的第五年进行比较，一次刈割测产的干物质产量每公顷可提高达１４７．２％、粗蛋白含量则提高２３３．７％，处理间均可达到极为显著的差异（Ｆ＝９．９０＞Ｆ０．０１＝３．３６）。后随着年限的推移，施氮肥的草场产量可保持一定的稳定性之后，再出现稳中有降，而不施氮肥的处理则在定植的第三年急剧下降。为此作者等提出了试验见解，希望对曼中田以及其类似地区禾本科草场的管理上能起到一定生态循环系统的指导作用，并为抑制害草飞机草的孳生危害提供措施。