Behavior of immunologically castrated barrows in comparison to gilts, physically castrated barrows, and intact male pigs.

The behavior of immunologically castrated barrows (IC; with Improvest; Zoetis, Parsippany, NJ) was compared with that of intact males (IM), physically castrated barrows (PC), and gilts (G). The study used 160 commercial crossbred pigs in a randomized complete block design (blocking factor was start date of study) and was performed over an 8-wk period from 16 wk of age (67.2 ± 2.50 kg BW) to a final BW of 126.5 ± 6.05 kg. The first Improvest dose was given to IC at the start of the study (d 0), and the second dose was given 28 d later. Pigs were housed in single-gender groups of 4 and had ad libitum access to feed and water. General, aggressive, and sexual behaviors were observed over a 12-h period from 0600 to 1800 h by the same trained investigators on d -1 (d prior to first dose), 13, 27 (day prior to second dose), 34, 41, and 55 of study (end of test). General behaviors (number of pigs lying, sitting, standing, at feeder, and at drinker) were recorded every 10 min in all pens (10 pens/gender), and aggressive (bites, head butts, and fights) and sexual (mounts) behaviors were recorded continuously over the 12-h period on a subsample of 4 pens/gender. There was no difference ( > 0.05) between the genders for lying, sitting, or drinker-related behavior. For the 4-wk period prior to second dose, a greater percentage of PC and G were at the feeder ( < 0.05) than IC or IM (8.0%, 7.4%, 10.2%, and 9.3% for IC, IM, PC, and G, respectively; SEM = 0.44). However, after the second dose, the percentage of pigs at the feeder was similar ( > 0.05) for IC, PC, and G and was greater ( < 0.05) for those genders than IM (10.1%, 7.1%, 10.0%, and 8.8%, respectively; SEM = 0.50). Prior to the second dose, the incidence of aggressive behaviors was generally greater for IC and IM compared with PC and G; however, after the second dose, the incidence of aggressive behaviors was similar for IC and PC and lower ( < 0.05) for those genders than for IM. The frequency of mounts for IC was greater ( < 0.05) than for PC before (25.5, 27.3, 2.5, and 1.5 total mounts/pen, respectively; SEM = 4.37) but not after ( > 0.05; 3.3, 33.3, 0.25, and 0.25 total mounts/pen, respectively; SEM = 1.15) the second dose. These results suggest that prior to the second Improvest dose, the behavior of IC was similar to that of IM and transitioned to become more similar to the behavior of PC after the second dose.

Growth performance of immunologically castrated (with Improvest) barrows (with or without ractopamine) compared to gilt, physically castrated barrow, and intact male pigs.

The study used a randomized complete block design (blocking factor was date of start on test) with 5 treatments: 1) physically castrated barrows (PC), 2) intact males (IM), 3) gilts (G), 4) immunologically castrated barrows (IC), and 5) immunologically castrated barrows fed ractopamine at 5 mg/kg (IC+RAC). The study used 192 pigs and was performed from the 16 wk of age (67.2 ± 2.52 kg BW) to a pen mean BW of 132.5 ± 3.60 kg. For IC+RAC, ractopamine was fed for the final 23 d of the study. Pigs were housed in groups of 4 (10 groups for PC, IM, G, and IC and 8 groups for IC+RAC) in a finishing building at a floor space of 1.18 m(2)/pig. Diets were formulated to meet requirements of IM except that the diet for the IC+RAC fed during the ractopamine feeding period was formulated to meet requirements of pigs on that treatment. Pigs had ad libitum access to feed and water throughout the study period and were individually weighed at the start, wk 2 and 4, and subsequently every week until the end of study. For the overall study period, IC had greater (P ≤ 0.05) ADG than the other genders (1,150, 1,024, 1,064, and 954 g/d for IC, PC, IM, and G, respectively; SEM = 25.8) and required fewer days to reach slaughter weight than the other genders (58.1, 61.6, 61.6, and 66.5 d for IC, PC, IM, and G, respectively; SEM = 1.26). Overall ADFI was less (P ≤ 0.05) for IM and G than IC and PC, which were similar (P > 0.05) in this respect (3.11, 3.06, 2.68, and 2.75 kg/d for IC, PC, IM, and G, respectively; SEM = 0.061). Overall G:F was greater (P ≤ 0.05) for IM than the other genders; IC had greater overall G:F than PC and G, which were similar in this respect (0.371, 0.335, 0.397, and 0.347 kg/kg for IC, PC, IM, and G, respectively; SEM = 0.0068). Immunologically castrated barrows had greater (P ≤ 0.05) ADG (30.7%) and ADFI (22.5%) than PC from the second week following the second Improvest dose to the end of the study. During the ractopamine feeding period, IC+RAC had greater (P ≤ 0.05) ADG (11.6%) and G:F (17.3%) than IC. The results of this study confirmed previously observed gender differences and effects of ractopamine on growth performance and that IC grew faster and had greater feed efficiency than PC during the study period.

Effects of immunological castration (Improvest) on changes in dressing percentage and carcass characteristics of finishing pigs.

The objective was to determine which tissue components contributed to the reduction in carcass yield of immunologically castrated (IC) barrows when compared to physically castrated (PC) barrows. The carcass yield of an IC barrow is less than the carcass yield of a PC barrow. This has historically been attributed to the presence of testicles, but the testes have only accounted for approximately 0.25% of live weight. This experiment included PC barrows, intact males, IC barrows, IC barrows fed ractopamine hydrochloride, and gilts. When the pigs reached 15 wk old, they were weighed, assigned to treatments (intact male or IC barrow), and penned in groups of 4 pigs per pen. Pigs designated for immunological castration were given injections at approximately 16 wk old and approximately 20 wk old. Pigs were eligible for harvest 33 d after the second injection when the average weight of the pen reached 130 kg. Immunologically castrated barrows lost on average 0.7% units more live weight during transport and lairage than PC barrows, intact males, or gilts. Physically castrated barrows had a 1.43% unit advantage over IC barrows in carcass yield. The differences in yield can be attributed to differences in testicles, reproductive tract, intestinal mass, gut fill, and some visceral organs. Testicle weight accounted for a 0.28% unit reduction in carcass yield of IC barrows when compared to PC barrows. Additional reproductive tract weights accounted for differences of 0.10% units. Intestinal mass (empty large intestine, small intestine, and stomach) was 0.2% units heavier in IC barrows when compared to PC barrows. Livers from IC barrows were 200 g heavier (P < 0.05) and kidneys were 40 g heavier than the same organs in PC barrows. These 2 organs combined for a 0.15% unit difference in carcass yield between IC and PC barrows. Gut fill, testicles, reproductive tract, intestinal mass, and the liver and kidney accounted for 0.97 of 1.43% unit differences in carcass yield between IC and PC barrows. Immunologically castrated barrows had less marbling than PC barrows, but there were no other differences in pork quality parameters. Cutability differences were less than reported in previous experiments, but IC barrows still had a 1.0% unit advantage in lean cutting yield and a 0.7% unit advantage in carcass cutting yield when compared to PC barrows.

Interactive effect of ractopamine and dietary fat source on pork quality characteristics of fresh pork chops during simulated retail display.

Crossbred pigs (n = 216) were used to test the interactive effect, if any, of ractopamine (RAC) and dietary fat source on the performance of finishing pigs, pork carcass characteristics, and quality of LM chops during 5 d of simulated retail display (2.6 degrees C and 1,600 lx warm-white fluorescent lighting). Pigs were blocked by BW and allotted randomly to pens (6 pigs/pen), and, after receiving a common diet devoid of RAC for 2 wk, pens within blocks were assigned randomly to 1 of 4 diets in a 2 x 2 factorial arrangement, with 5% fat [beef tallow (BT) vs. soybean oil (SBO)] and RAC (0 vs. 10 mg/kg). Diets were formulated to contain 3.1 g of lysine/Mcal of ME and 3.48 Mcal/kg of ME. Across the entire 35-d trial, pigs fed RAC had greater (P < 0.01) ADG and G:F, but RAC did not affect (P = 0.09) ADFI; however, performance was not affected (P >or= 0.07) by dietary fat source. Carcass weight, LM depth, and lean muscle yield were increased (P < 0.01), whereas fat depth was decreased (P = 0.01), in carcasses from RAC-fed pigs; however, carcass composition measures were similar (P >or= 0.27) between fat sources. Feeding 10 mg/kg of RAC reduced (P

Measuring synthesis rates of nitrogen-containing polymers by using stable isotope tracers.

The major N-containing polymer compounds in the body include protein, RNA, and DNA. The endogenous gastrointestinal secretions as well as the portal-drained visceral and peripheral immune responses are basic physiological functions. Elevated endogenous secretions and immune activities, as affected by developmental stages, diets, and management factors, decrease the availability of dietary nutrients for peripheral muscle synthesis and deposition. Measurements of in vivo protein, RNA, and DNA synthesis rates associated with the viscera, peripheral immune cells, and skeletal muscles should, in principle, be the sensitive biochemical and cellular endpoints for studying factors affecting nonruminant nutrition, metabolism, and growth. The selection of stable isotope tracers for precursors, routes of tracer delivery, and mass spectrometric analyses of tracer enrichments are the major methodological considerations. To measure in vivo protein, RNA, and DNA synthesis rates, oral feeding with heavy water (2H2O), and continuous infusion of [U-13C]glucose and [15N]Gly intravenously for labeling the sugar moieties ribose and deoxyribose and de novo purine base synthesis have been established. Flooding doses of tracer Phe, for example, L-[ring-2H5]Phe, via the i.p. route are reliable and cost-effective for measuring in vivo protein synthesis rates, especially for the viscera in small nonruminants. Therefore, measurements of the major N-containing polymer synthesis rates in the viscera, the peripheral immune cells, and muscles through oral feeding with 2H2O and/or i.p. flooding doses of Phe tracers are the emerging tools for studying nonruminant nutrition, metabolism, and growth under research and field test conditions.

Gastric cannulation of pregnant sows.

The purpose of this project was to study the effect of superalimentation in lactating sows through permanent, surgically placed, gastric cannulas. A surgical technique was developed to install gastric cannulas into pregnant sows to allow superalimentation by introducing feed through the cannula. After induction of general anesthesia, a flexible, T-shaped cannula (22 mm outside diameter) was surgically placed in the dorsal portion of the greater curvature of the stomach and exteriorized through the tenth intercostal space approximately 30 cm left of the dorsal midline. Cannulas were installed on day 85 +/- 5 days of gestation. Anesthesia, surgical procedures, and the subsequent presence of the cannula did not affect the size or number of live pigs at birth. In addition, the prevalence of stillbirths and mummified fetuses was not significantly different than that of noncannulated sows. The gastric cannulas did not affect lactation performance, as litter size and weight were unaffected when compared with that in noncannulated controls. Postmortem examination of euthanatized sows revealed adhesions of the gastric wall to the abdominal wall, thus eliminating the possibility of leakage of the gastric contents into the peritoneum. Detrimental effects of the cannulas on gastric function or capacity were not detected, and cannulas could be maintained through multiple parities.

Porcine zona pellucida: association of sperm receptor activity with the alpha-glycoprotein component of the Mr = 55,000 family.

The immunogenicity and sperm receptor activity of five preparations of the major porcine zona pellucida glycoprotein family ZP3 (Mr = 55,000) were investigated. These included (1) ZP3, a chromatographically purified preparation of the 55,000 family; (2) ZP3 alpha, and (3) ZP3 beta, the two-component glycoproteins of the ZP3 family; (4) ZP3-EBGD, a partially deglycosylated preparation of ZP3 obtained by enzymatic treatment; and (5) ZP3-DG, a chemically deglycosylated preparation of ZP3. Titer studies using mouse and rabbit antisera prepared against each preparation yielded the following order of immunogenicity: ZP3 and ZP3 beta greater than ZP3-EBGD and ZP3 alpha greater than ZP3-DG, indicating that ZP3 becomes less immunogenic as more carbohydrate is removed. Pretreatment of intact zona with the various antisera prior to zona exposure to sperm resulted in an inhibition of sperm attachment to those zona treated with antibodies to ZP3, ZP3-EBGD, and ZP3 alpha. Pretreatment of zona with antibodies to ZP3 beta and ZP3-DG had no effect on sperm attachment. Studies involving pretreatment of boar sperm with the various ZP3 preparations prior to their use in a sperm-zona attachment assay and investigations involving displacement of the radiolabeled ZP3 preparations from sperm by unlabeled ZP3 preparations also yielded findings similar to the antibody studies. Collectively, these data indicate that ZP3 alpha probably functions as a zona receptor for boar sperm and that carbohydrate has an important role in maintaining the functional integrity of the ZP3 alpha glycoprotein.