Reproductive and economic impact following controlled introduction of cattle persistently infected with bovine viral diarrhea virus into a naive group of heifers.

The reproductive impact following controlled introduction of animals persistently infected (PI) with bovine viral diarrhea virus (BVDV) was evaluated in BVDV-naive heifers. Heifers were randomly allocated into two groups: an unexposed control herd (n = 34) and a herd exposed to five persistently infected (PI) animals for 7 mo, beginning 50 days before the breeding season (n = 34). Initiation of the BVDV-challenge was timed to mimic either direct contact with PI calves born in the previous calving season or accidental introduction of PI herd additions prior to the breeding season. The PI animals represented BVDV Types 1a (n = 3), 1b (n = 1) and 2 (n = 1). Two BVDV-free, seropositive bulls were used in each group for 78 days breeding seasons. In both groups, 33 of 34 heifers became pregnant, with similar distribution of fetal ages. Two heifers in each group aborted (etiology undetermined). In addition, one calf was born dead and one calf died 3 days post-partum in the BVDV-exposed group. One calf in the unexposed group died 4 mo post-partum. No calves, including the stillborn calf and the two calves that died prior to weaning, were persistently infected with BVDV. In summary, introduction of PI cattle to a group of BVDV-naive heifers 50 days prior to the breeding season did not negatively impact reproductive performance. To the contrary, the active immunity that developed following field exposure to BVDV provided effective reproductive and fetal protection during the breeding season and subsequent gestations, despite continuous exposure to PI animals until approximately midgestation. Although BVDV can have potentially devastating reproductive effects, timing of infection is a critical determinant in the outcome of a BVDV infection. A controlled breeding season with introduction of herd additions at less critical reproductive time points can mitigate the negative reproductive health consequences of BVDV.

Inactivation at various temperatures of bovine viral diarrhea virus in beef derived from persistently infected cattle.

Bovine viral diarrhea virus (BVDV) is a pestivirus that is enzootic in most cattle populations throughout the world. This virus is present throughout the body of persistently infected (PI) cattle. Previous research has not assessed the cooking temperature at which BVDV in meat from PI cattle can be inactivated. Therefore, muscle tissue from 6 PI cattle was harvested, refrigerated, frozen, and heated to various internal temperatures. The concentration of virus present was determined by virus isolation. Average cell culture infective doses (50% endpoint; CCID(50)) of BVDV per gram of frozen, uncooked meat from PI cattle were 10(5.85) CCID(50)/g of whole cuts and 10(6.02) CCID(50)/g of ground meat. The virus in whole and ground meat was consistently inactivated when cooked to temperatures greater than or equal to 75°C. A second objective of this research was to thoroughly reassess if Vero cells were permissive to BVDV infection in our laboratory to provide further indication of whether primates, including humans, might be susceptible to BVDV. Vero cells were not permissive to infection with any of 43 different strains of BVDV that readily replicated in Madin Darby bovine kidney cells. In conclusion, this bovine pathogen, which is not considered to be a human pathogen, can be inactivated by cooking ground or whole cuts of meat to 75°C or higher. Care should be taken to ensure that susceptible hosts such as pigs are not fed improperly cooked meat, meat by-products, or waste food originating from PI cattle.

Intrauterine inoculation of seronegative heifers with bovine viral diarrhea virus concurrent with transfer of in vivo-derived bovine embryos.

Bovine viral diarrhea virus (BVDV) has been shown to be associated with single transferable in vivo-derived bovine embryos despite washing and trypsin treatment. Hence, the primary objective was to evaluate the potential of BVDV to be transmitted via the intrauterine route at the time of embryo transfer. In vivo-derived bovine embryos (n=10) were nonsurgically collected from a single Bos tarus donor cow negative for BVDV. After collection and washing, embryos were placed into transfer media containing BVDV (SD-1; Type 1a). Each of the 10 embryos was individually loaded into an 0.25-mL straw, which was then nonsurgically transferred into the uterus of 1 of the 10 seronegative recipients on Day 0. The total quantity of virus transferred into the uterus of each of the 10 Bos tarus recipients was 878 cell culture infective doses to the 50% end point (CCID(50))/mL. Additionally, control heifers received 1.5 x 10(6) CCID(50) BVDV/.5 mL without an embryo (positive) or heat-inactivated BVDV (negative). The positive control heifer and all 10 recipients of virus-exposed embryos exhibited viremia by Day 6 and seroconverted by Day 15 after transfer. The negative control heifer did not exhibit a viremia or seroconvert. At 30 d after embryo transfer, 6 of 10 heifers in the treatment group were pregnant; however, 30 d later, only one was still pregnant. This fetus was nonviable and was positive for BVDV. In conclusion, the quantity of BVDV associated with bovine embryos after in vitro exposure can result in viremia and seroconversion of seronegative recipients after transfer into the uterus during diestrus.

Effect of the degree and duration of early dietary amino acid restrictions on subsequent and overall pig performance and physical and sensory characteristics of pork.

The objective of this study was to investigate the effect of the degree and duration of early dietary AA restrictions on subsequent and overall pig performance and physical and sensory characteristics of pork. For the grower (G) and finisher-1 (F1) phases, 3 corn-soybean meal diets were formulated to contain 100, 80, or 60% of the 1998 NRC total Lys recommendations (100G, 80G, or 60G, and 100F1, 80F1, or 60F1, for the G and F1 phases, respectively). For the finisher-2 (F2) phase, a common corn-soybean meal diet was formulated to satisfy the 1998 NRC total Lys recommendation. Thirty gilts and 30 castrated males (2 gilts or 2 castrated males/pen) were randomly assigned to 5 dietary treatments (100G-100F1, 80G-100F1, 80G-80F1, 60G-100F1, and 60G-60F1) when BW was 22.7 +/- 0.3 kg. Pigs were switched to F1 and F2 diets at 50.7 +/- 0.4 and 79.9 +/- 0.5 kg of BW, respectively. Pigs had ad libitum access to feed and water. All pigs were slaughtered at 110.7 +/- 0.5 kg of BW, and LM samples were collected. Pigs fed the 60G diet had less (P < or = 0.05) ADG during the G phase and greater (P < or = 0.05) ultrasound backfat (UBF) at the end of the G phase than those fed the 100G diet. The ADG decreased linearly (R(2) = 0.70; P < 0.001) as the degree of AA restrictions became more severe. Although serum total protein (TP) and albumin concentrations in pigs fed the 60G-100F1 diets were less (P < or = 0.05) than those fed the 100G-100F1 diets at the end of the G phase, TP concentration was similar between the 2 groups at the end of the F1 phase. Likewise, ADG during the F1 phase and UBF at the end of the F1 phase in pigs fed the 60G-100F1 diets were similar to those fed the 100G-100F1 diets. Feeding the 80G diet resulted in numerically decreased ADG during the G phase, but there was no difference in ADG during the F1 and F2 phases or UBF at the end of F1 and F2 phases between pigs fed the 80G and 100G diets. Overall, pigs fed the 80G-80F1 diets had similar ADG, but less (P < or = 0.05) fat-free lean gain (LG) than those fed the 100G-100F1 diets. These pigs also had less (P < or = 0.05) serum TP and albumin concentrations than pigs fed the 100G-100F1 diets throughout the study. Pigs fed the 60G-60F1 diets had less (P < or = 0.05) overall ADG and G:F and less (P < or = 0.05) LM area and LG than those fed the 100G-100F1 diets. However, they had a greater (P < or = 0.05) subjective marbling score than those fed the 100G-100F1 diets. The results indicated that pigs fed the 80G-80F1 diets may have exhibited compensatory growth in BW gain, but not in terms of lean accretion. Growth performance and carcass traits of pigs fed the 60G-60F1 diets were reduced, indicating that the restriction may have been too severe or too long or both. Early dietary AA restrictions had no clear effect on physical and sensory characteristics of pork.

Amino acid supplementation of hydrolyzed feather meal diets for finisher pigs.

The objective of this study was to determine the possibility of replacing soybean meal (SBM) in finisher pig diets completely with hydrolyzed feather meal (FM). Forty-five gilts and 45 castrated males (57.8+/-0.8 kg of BW; 3 gilts or 3 castrated males/pen) were randomly assigned to 5 finisher-1 diets with 6 pens per diet. At an average pen BW of 81.0+/-1.4 kg, pigs were offered finisher-2 diets. Corn-SBM, finisher-1 and finisher-2 positive control (PC) diets were formulated to contain 6.1 and 4.7 g of apparent ileal digestible (AID) Lys/kg, respectively. Corn-FM negative control (NC) diets were formulated to be iso-N to the PC diets. The NC diets were supplemented with Lys and Trp (NRC; NC + Lys and Trp) to alleviate apparent deficiencies based on AID AA in FM reported by the 1998 NRC. In addition, the NC diets were supplemented further with the third limiting AA, Thr (40+3AA; NC + Lys, Trp, and Thr), and fourth and fifth limiting AA, His and Ile (40+5AA; NC + Lys, Trp, Thr, His, and Ile), based on the assumption that the apparent ileal digestibility of all indispensable AA in FM is 40%. Pigs had ad libitum access to feed and water. At the end of the study (112.1+/-1.8 kg), blood samples were collected from all pigs before slaughter. As expected, overall ADFI, AID Lys (representing indispensable AA) intake (LysI), ADG, and G:F were greater and BW gain:LysI (G:LysI) was less in pigs fed the PC diet than those fed the NC diet (P<0.001). Pigs fed the NRC diet grew slower than those fed the PC diet (P=0.004), and their G:LysI tended to be less than those fed the PC (P=0.083) or the 40+3AA and 40+5AA diets (P=0.094). Greater fat-free lean percentage (P=0.005), fat-free lean gain (LG; P<0.001), and LG:F (P<0.001) were observed in pigs fed the PC diet compared with those fed the NC diet, but their LG:F or LG:LysI was similar to those fed the NRC diet. However, LG:F (P=0.030) and LG:LysI (P=0.028) were greater in pigs fed the 40+3AA and the 40+5AA diets than those fed the NRC diet. Pigs fed the 40+5AA diet tended to utilize AID Lys more efficiently for LG than those fed the 40+3AA diet (P=0.068). Subjective meat color (P<0.001), firmness (P=0.004), and marbling (P<0.001) scores were greater in pigs fed the 40+5AA diet than those fed the 40+3AA diet. Diets seemed to have no clear effect on the weight of liver, kidney, and heart or serum urea N and triacylglycerides. Pigs fed the PC diet had more serum albumin and total protein (P<0.001), but less glucose (P=0.031) and cholesterol (P<0.001) than those fed the NC diet. Serum total protein was greater (P=0.031) in pigs fed the 40+5AA diet than those fed the 40+3AA diet. The results indicated that the corn-FM diets were not as effective as the corn-SBM diet in supporting BW gain of finisher pigs. However, the results seemed to indicate that pigs fed the corn-FM diet supplemented with the necessary AA can utilize feed and AA for BW gain and lean gain as efficiently as those fed the corn-SBM diet. Further research is needed to explore fully the optimal AA supplementation strategy to effectively utilize FM for pig production.

Prevalence of Tritrichomonas foetus in several subpopulations of Alabama beef bulls.

The objective of this study was to estimate the prevalence of Tritrichomonas foetus infections in Alabama (USA) beef bulls through prospective and retrospective surveys. The prospective survey included 240 Alabama beef bulls that were sampled between January 2005 and March 2006. Preputial smegma was collected from the 240 bulls with a dry pipette and cultured in an InPouch TF T. foetus culture pouch (BioMed Diagnostics; White City, OR, USA). The samples were evaluated microscopically once a day for 6 days for growth resembling T. foetus. To avoid false-positives due to fecal trichomonads, all suspect cultures were sent to both the Alabama Department of Agriculture Veterinary Diagnostic Laboratory in Auburn, AL, USA and the Auburn University College of Veterinary Medicine Parasitology Laboratory (Auburn, AL, USA) for polymerase chain reaction (PCR) confirmatory assays. Of the 240 bulls cultured in the prospective survey, 3 (1.25%) cultures were considered suspect on microscopic evaluation. However, PCR-based assays were negative for T. foetus, suggesting that the samples most likely contained fecal trichomonads. The retrospective analysis included 374 T. foetus cultures performed at the Alabama Department of Agriculture Veterinary Diagnostic Laboratory between October 2002 and March 2005. Of the 374 bulls included in the retrospective analysis, only 1 (0.27%) was confirmed positive by a PCR-based assay.