Browsing by Author "Wang, Chong"

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    Comparison of Commercial Real-Time Reverse Transcription-PCR Assays for Reliable, Early, and Rapid Detection of Heterologous Strains of Porcine Reproductive and Respiratory Syndrome Virus in Experimentally Infected or Noninfected Boars by Use of Different Sample Types
    Gerber, Priscilla F.; O'Neill, Kevin; Owolodun, Olajide; Wang, Chong; Harmon, Karen; Zhang, Jianqiang; Halbur, Patrick G.; Zhou, Lei; Meng, Xiang-Jin; Opriessnig, Tanja (American Society for Microbiology, 2012-12-05)
    The aims of this study were to compare three commercial porcine reproductive and respiratory syndrome virus (PRRSV) real-time reverse transcription-PCR (RT-PCR) assays for detection of genetically diverse PRRSV isolates in serum, semen, blood swabs, and oral fluids collected from experimentally infected boars and to evaluate the effects of sample pooling. Six groups of three boars negative for PRRSV were each inoculated with one of six PRRSV isolates (sharing 55 to 99% nucleotide sequence identity in ORF5). Samples were collected on days -2, 1, 3, 5, 7, 14, and 21 postinoculation (p.i.) and tested by one of three commercially available real-time RT-PCR assays(VetMax from Applied Biosystems, Foster City, CA [ abbreviated AB]; VetAlert from Tetracore, Rockville, MD[TC]; and AcuPig from AnDiaTec GmbH, Kornwestheim, Germany [ AD]). At day 1 p.i., all assays detected at least one positive sample in each group. The highest detection rates were on days 3 and 5 p.i. Between days 1 and 7 p.i., serum samples had the highest detection rate (90%) with 100% agreement between tests, followed by blood swabs (kappa value of 0.97) and semen (kappa value of 0.80). Oral fluids had the lowest detection rates (AB, 55%; TC, 41%; AD, 46%) and the highest disagreement between kits (kappa value of 0.63). Pools of five samples did not reduce the detection rates if there was one positive sample with a large amount (cycle threshold,< 30) of viral RNA in the pool. Serum and blood swab samples had shorter turnaround times for RNA extraction. The AB assay had a 1.6-times-shorter PCR time. In summary, serum and blood swabs had the best performance with highest detection rates and agreement between assays and the shortest turnaround times.
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    Ruminal volatile fatty acid absorption is affected by elevated ambient temperature
    Bedford, Andrea; Beckett, Linda; Harthan, Laura; Wang, Chong; Jiang, Ning; Schramm, Hollie H.; Guan, Leluo; Daniels, Kristy M.; Hanigan, Mark D.; White, Robin R. (2020-08-04)
    The objective of this study was to investigate the effect of short-term elevated ambient temperature on ruminal volatile fatty acid (VFA) dynamics and rumen epithelium gene expression associated with the transport and metabolism of VFA. Eight ruminally cannulated Holstein heifers (200 kg) were used in a factorial, repeated measures experiment with two treatments and two periods. During the first period, animals were provided with feed ad libitum and housed at 20 degrees C. During the second period, one group (HS) was housed at 30 degrees C and fed ad libitum. The other group (PF) was housed at 20 degrees C and pair-fed to match the intake of the HS group. During each period, animals were kept on treatment for 10 day, with sample collection on the final day. In the second period, indicators of heat stress were significantly different between PF and HS animals (P<0.05). There was a thermal environment effect on butyrate production (P<0.01) that was not associated with feed intake (P=0.43). Butyrate absorption decreased in HS animals (P<0.05) but increased in PF animals (P<0.05) from period 1 to period 2. There was a feed intake effect on BHD1 expression (P=0.04) and a tendency for a thermal environment effect (P=0.08), with expression increasing in both cases. Expression of MCT4 was affected by feed intake (P=0.003) as were all NHE genes (NHE1, NHE2, and NHE3; P<0.05). These results indicate that with low feed intake and heat stress, there are shifts in rumen VFA dynamics and in the capacity of the rumen epithelium to absorb and transport VFA.
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    Weaning Performance of Beef Cattle Calves Based on Concentrate Intake
    Wang, Chong; Li, Dongping; Yang, Jinyong; Xia, Yuefeng; Tu, Yan; White, Robin R.; Gao, Hui; Diao, Qiyu; Mao, Huiling (MDPI, 2019-12-20)
    This study was conducted to investigate the effects of weaning based upon different concentrate intake on growth performance, health, and antioxidant status of Southern Chinese Cattle. Thirty female calves were used in the trial. Weaning strategy was the primary variable of interest and treatments included weaning when a calf consumed 1000 (W1000), 750 (W750), or 500 (W500) g of starter for three consecutive days. All calves received colostrum within 4 h of birth and colostrum intake was monitored to ensure all calves consumed 1.5 L within 12 h of birth. Calves were then fed fresh milk up to 2 L/d for 7 days. Between d 7 and 13, calves were fed a liquid feed composed of 50% fresh milk, and 50% milk replacer (MR) at maximum rate of 3 L/d. For the remainder of the study, calves were provided 3 L/d MR. Concentrate (starter), and grass hay were available ad libitum starting on d 1. Milk, MR, starter, and hay intakes were recorded daily. Calf body weights and measurements were recorded at birth and every 4 wk until weaning. Average weaning ages were 48 ± 4.5, 58 ± 4.6, and 65 ± 4.8 for W500, W750, and W1000, respectively. Between wk 8 and wk 21, calves in the W500 and W750 treatments had higher (p < 0.05) starter intakes than calves in the W1000 treatment. Body height, body length, circumference of cannon bone, circumference of the chest did not differ with weaning strategy (p > 0.05). There was no difference in body weight (BW) and average daily gain (ADG) on wk 5 when any of the calves were weaned (p > 0.05). In wk 9, BW of calves in W1000 tended to be higher than that of W750 and W500 (p = 0.10). However, calves in W1000 lost their BW advantage in wk 13. Calves’ ADG was not different during the whole experiment period among treatments. Calves in W750 had higher plasma BHBA and the total antioxidant capacity which has been associated with a positive impact on health. Data in this experiment suggest that weaning when calves consume 750 g of starter can enhance ADG, DMI, feed efficiency, and selected blood parameters compared with weaning when calves consume 500 g of starter.