Assessment of general risk posed from transgenic (T) animals is important to their future contributions to society. Identification of potentially harmful properties of transgenic livestock is the initial step in a risk assessment. We previously developed and characterized transgenic swine containing a mammary-specific transgene (bovine a-lactalbumin, bALAC) that results in increased milk production in sows. We are currently determining whether bALAC is expressed in tissues of T swine other than the lactating mammary gland and whether the transgene DNA (Tg) crosses into nontransgenic control (C) swine under various physiological and physical conditions. The specific aims addressed in the present study were to determine (1) whether the Tg can be transferred directly by physical association or contact; (2) whether the Tg can be transferred directly via mating; (3) whether the Tg can be transferred directly during gestation and parturition; and (4) whether the Tg can be transferred directly during lactation. The T animals utilized in these studies are in at least generation 10 and have stable incorporation of the Tg. Comparable age- and weight-matched animals, T and C, were housed together allowing general contact that is normal in swine production, for either 180, 220, or 250 days of age after weaning. Swine typically ingest saliva, regurgitated food, and stool or urinary products, as well as other bodily fluids and cells during normal housing. In the second study, vaginal, cervical, uterine, oviductal, and ovarian tissues from C females on 2, 7, or 90 days after mating to T males, and penis, bulbourethral gland, urethra, testis, and epididymis tissues from C males on 2 or 7 days after mating to Tg females were collected. The presence of Tg in tissues from all C animals was tested by using PCR. We have analyzed for the presence of the Tg in various tissues [including mammary gland, salivary gland, skin (sebaceous gland), muscle, lung, liver, kidney, brain, ovary, oviduct, uterus, cervix, vagina, penis, bulbourethral gland, urethra, testis, epididymis, blood, inner and outer placental membranes and intestine]. Results indicate no presence of the Tg in tissues of C animals (n = 28) after co-habitation for 180, 220, or 250 days (n = 305 samples analyzed) or at 2 (n = 7), 7 (n = 16), or 90 (n = 6) days post-mating (n = 72, 192, or 71 samples analyzed, respectively). At Day 112 of gestation, all the samples (n = 78 samples analyzed) from nontransgenic piglets (n = 13) whose dam was aTg female were negative except for the outer placental membrane (n = 13), which screened positive for the transgene. This is not surprising because the outer placental membrane is in close contact with the uterus of the Tg dam. Finally, control piglets (n = 4) that were cross-fostered (3 days after birth) and suckled Tg dams showed no evidence of the transgene in their tissues (n = 20 samples analyzed) at weaning. The present results suggest that there is no horizontal Tg transmission between T and C pigs caused by rearing, mating, gestation, or lactation. This project was supported by USDA BRAG Project #2005-03799.

Assessment of general risk posed from transgenic (T) animals is important to their future contributions to society. Identification of potentially harmful properties of transgenic livestock is the initial step in a risk assessment. Direct and indirect impacts of potential harmful properties of T livestock need to be evaluated at 3 levels, namely (1) characterization of how the transgene, its product, and the T livestock behave in their immediate environment, that is, in their barn or pen; (2) determination of possible impacts of large-scale release of T livestock, that is, if they were to be integrated into the larger population of food animal livestock; and (3) determination of the more complex environmental and safety consequences of their release into livestock populations. We previously developed and characterized transgenic swine containing a mammary-specific transgene (bovine α-lactalbumin, bALAC) that results in increased milk production in sows. We currently are determining whether bALAC is expressed in tissues of T swine other than the lactating mammary gland and whether the transgene DNA (Tg) crosses into non-transgenic control (C) swine under various physiological and physical conditions. The specific aims addressed in the present study were to determine: (1) whether the Tg can be transferred directly from T animals to C animals by physical association or contact and (2) whether the Tg can be transferred directly from an adult T animal to an adult C animal via mating. The T animals utilized in these studies are in at least generation 10 and have stable incorporation of the Tg. Comparable age- and weight-matched animals, T and C, were housed together allowing for general contact that is normal within swine production, for either 180, 220, or 250 d of age after weaning. Swine due to their behavior ingest saliva, regurgitated food, and stool or urinary products, as well as other bodily fluids and cells during normal housing. In a second study, vaginal, cervical, uterine, oviductal, and ovarian tissues from C females on 2, 7, or 90 d after mating to T males and penis, bulbourethral gland, urethra, testis, and epididymis tissues from C males on 2 or 7 days after mating to Tg females were collected. The presence of Tg in tissues from all C animals was tested via PCR. We have analyzed for the presence of the Tg in various tissues [including mammary gland, salivary gland, skin (sebaceous gland), muscle, lung, liver, kidney, brain, ovary, oviduct, uterus, cervix, vagina, penis, bulbourethral gland, urethra, testis, epididymis, and intestine]. Results indicate no presence of the Tg in tissues of C animals (n = 28) after co-habitation for 180, 220, or 250 d (n = 305 samples analyzed) or at 2 (n = 5), 7(n = 14), or 90 (n = 2) d post-mating (n = 60, 174, or 24 samples analyzed, respectively). The present results suggest that there is no horizontal Tg transmission between T and C pigs due to rearing or mating. This work provides a critical step toward providing rigorous scientific data for risk assessment of transgenic livestock. This project supported by the USDA BRAG Project #2005-03799.

Assessment of the general risk posed by transgenic animals is important to their future contributions to society. Identification of potentially harmful properties of transgenic livestock is the initial step in a risk assessment. Direct and indirect impacts of potential harmful properties of transgenic livestock need to be evaluated at 3 levels: (1) characterization of how the transgene, the transgene product, and the transgenic livestock behave in their immediate environment; that is, in their barn or pen; (2) determination of possible impacts of large-scale release of transgenic livestock; that is, if they were to be integrated into the larger population of food animal livestock; and (3) determination of the more complex environmental and safety consequences of their release into the livestock population. We previously developed and characterized transgenic swine containing a mammary-specific transgene (bovine α-lactalbumin, bALAC) that results in increased milk production in sows (Bleck et al. 1998). We are currently determining whether bALAC is expressed in tissues of transgenic (T) swine other than the lactating mammary gland, and whether the transgene (DNA; Tg) crosses into non-transgenic control (C) swine under various physiological and physical conditions. The specific aims addressed in the present study were to determine (1) whether the Tg can be transferred directly from T animals to C animals by physical association or contact, and (2) whether the Tg can be transferred directly from an adult T animal to an adult C animal via mating. The T animals utilized in these studies were in generation 10 at least and have stable incorporation of the Tg. Comparable age- and weight-matched animals, T and C, were housed together allowing for general contact that is normal within swine production, for 180, 220, or 250 days after weaning. Due to the nature of swine behavior, these animals may ingest saliva, regurgitated food, and stool and urinary products as well as other bodily fluids and cells during normal housing and establishment of dominance hierarchy. In a second study, vaginal, cervical, uterine, oviductal, and ovarian tissues were collected from C females on 2 or 7 days after mating to T males. The presence of Tg in tissues from all C animals was tested via PCR. We have analyzed for the presence of the Tg in various tissues, including mammary gland, salivary gland, skin (sebaceous gland), muscle, lung, liver, kidney, brain, ovary, oviduct, uterus, cervix, vagina, and intestine. Preliminary results indicate no presence of the Tg in tissues of C animals (n = 20) after cohabitation for 180, 220, or 250 days (n = 201 samples analyzed) or at 2 (n = 3) or 7 (n = 5) days post-mating (n = 38 and 59 samples analyzed, respectively). This work provides a critical first step toward providing rigorous scientific data for risk assessment of transgenic livestock. The USDA BRAG Program, Project No. 2005–03799, supported this work.

Two studies were conducted at two locations to evaluate growth performance and carcass characteristics of growing-finishing pigs fed diets containing either YieldGard Rootworm corn (MON 863), a non-transgenic genetically similar corn (RX670), or two conventional nontransgenic corn hybrids (DK647 and RX740). A randomized complete block design with a 2 x 4 factorial arrangement of treatments (two genders and four corn hybrids) was used. Study 1 used 72 barrows and 72 gilts (progeny of Danbred sires x [Danbred x NE White line] dams grown from 22.7 to 117.0 kg BW). Pigs were housed in a modified open-front building in single-gender groups of six (six pens per dietary treatment). Study 2 used 80 barrows and 80 gilts (progeny of PIC 337 sires x C22 dams) grown from 29.5 to 114.9 kg BW. Pigs were housed in an environmentally controlled finishing building in single-gender groups of five (eight pens per dietary treatment). The test corns were included at a fixed proportion of the diet in both studies. Animals had ad libitum access to feed and water. Pigs were slaughtered at the end of the growth period using standard procedures, and carcass measurements were taken. There were no diet x gender interactions for growth performance or carcass measurements in either study. In both studies, overall ADG, ADFI, and G:F were not affected by corn hybrid. There was no effect of corn hybrid on carcass or LM quality measurements in Study 1. In Study 2, LM protein content was less (P< 0.05) for pigs fed RX740 compared with those fed either MON 863 or RX670; however, there was no effect of corn hybrid on other LM composition measures or on quality traits. In both studies, differences between barrows and gilts for growth and carcass traits were similar to previous research. These results suggest that the YieldGard Rootworm corn (MON 863) results in equivalent growth performance and carcass quality to nontransgenic corn hybrids in growing-finishing pigs.

Two studies were conducted at two locations to evaluate growth performance and carcass characteristics of growing-finishing pigs fed diets containing either glyphosate-tolerant Roundup Ready (event nk603) corn, a nontransgenic genetically similar control corn (RX670), or two conventional sources of nontransgenic corn (RX740 and DK647). A randomized complete block design (three and four blocks in Studies 1 and 2, respectively) with a 2 x 4 factorial arrangement of treatments (two genders and four corn lines) was used. Study 1 used 72 barrows and 72 gilts (housed in single-gender groups of six; six pens per dietary treatment) with initial and final BW of approximately 22 and 116 kg, respectively. Study 2 used 80 barrows and 80 gilts (housed in single-gender groups of five; eight pens per dietary treatment) with initial and final BW of approximately 30 and 120 kg, respectively. Pigs were housed in a modified open-front building in Study 1 and in an environmentally controlled finishing building in Study 2. The test corns were included at a fixed proportion of the diet in both studies. Animals had ad libitum access to feed and water. Pigs were slaughtered using standard procedures and carcass measurements were taken. In Study 1, overall ADG, ADFI (as-fed basis), and gain:feed (G:F) were not affected (P > 0.05) by corn line. In Study 2, there was no effect of corn line on overall ADFI (as-fed basis) or G:F ratio. In addition, overall ADG of barrows fed the four corn lines did not differ (P > 0.05); however, overall ADG of gilts fed corn DK647 was greater (P < 0.05) than that of pigs fed the other corn lines. There was no effect (P > 0.05) of corn line on carcass yield or fatness measurements in either study. Differences between barrows and gilts for growth and carcass traits were generally similar for both studies and in line with previous research. Overall, these results indicate that Roundup Ready corn (nk603) gives equivalent animal performance to conventional corn for growing pigs.