Evaluation of Improvest effects on production parameters of gilts from two different genetic sire lines

The objective was to evaluate the effects of Improvest on the performance and carcass characteristics of gilts from two different genetic sire lines and the performance of Improvest gilts with castrated male pigs. It was hypothesized that performance parameters observed for Improvest gilts would be similar to barrows, thus narrowing the performance gaps between traditionally managed gilts and barrows. Pigs were from Large White/Landrace dams and either Duroc-Pietrain (DP) or Duroc (D) sires. Females within each genetic sire line were randomized by weight to receive the first dose of Improvest (IMP) on day 25 of the study or to serve as a nontreated control (DP IMP gilt (n = 6 pens; 19 pigs/pen), D IMP gilt (n = 6 pens; 19 pigs/pen), DP CON gilt (n = 6 pens; 19 pigs/pen), D CON gilt (n = 6 pens; 19 pigs/pen). The second dose of Improvest was administered 6 wk later (i.e., day 67). Barrows did not receive Improvest (DP barrow [n = 10 pens; 19 to 20 pigs/pen], D barrow [n = 10 pens; 19 to 20 pigs/pen]). Average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F) were measured at 21 d intervals throughout the duration of the study. The targeted weight for pigs to be marketed was 133 ± 2.5 kg. Carcass characteristics and loin quality parameters were evaluated on a subset of pigs (n = 283). Improvest-treated gilts of both genetic lines had increased (P ≤ 0.05) ADG and ADFI compared to untreated gilts during the post-second dose intervals with values exceeding that of barrows from day 84 to marketing. Overall, DP IMP gilts had increased (P ≤ 0.05) G:F post-second dose compared to DP CON gilts and DP barrows, yet all other treatments were similar. As pigs were marketed at a similar weight, there was no difference in the final weight, however, DP IMP gilts and DP barrows reached market weight sooner (P ≤ 0.05) than DP CON gilts (109.9 and 111.8 vs. 114.3 ± 0.8 d). Backfat and loin weight were greater (P < 0.01) in IMP gilts versus CON gilts, while IMP gilts and barrows had similar values within each respective genetic sire line. There were no differences between treatments (P ≥ 0.08) for pH and instrumental color of the loins. When the pass rate of loins (Japanese color score ≥ 3.0 and marbling ≥ 2.0) was evaluated, IMP gilts were at intermediate values between CON gilts and barrows for each respective genetic sire line. Overall, Improvest within a genetic line improved gilt carcass measurements so that they were more similar to barrows.

The effect of timing of Improvest administration on growth performance and carcass characteristics in gilts

Improvest (IMP; Zoetis Inc., Parsippany, NJ) has been approved by the U.S. Food and Drug Administration for use in gilts. Improvest is administered twice: the first dose should be administered no earlier than 9 wk of age and the second dose (D2) at least 4 wk after the first dose. The aim of this study was to determine how the timing of IMP before harvest affects growth performance and carcass characteristics in gilts. A total of 1,632 gilts were allocated to four groups (12 pens/treatment; 34 gilts/pen): 1) a control group did not receive IMP; 2) T-early gilts received IMP on day 7 (day 0 = 10 wk postweaning), and D2 on day 40 (i.e., 35 d prior to first removal for harvest); 3) T-medium gilts received IMP on day 21 and D2 on day 56 (i.e., 19 d prior to first removal for harvest); 4) T-late gilts received IMP on day 35 and D2 on day 70 (i.e., 5 d before first removal for harvest). Pigs were selected for harvest by visual observation on days 75, 89, 103, and 117: 1) the heaviest 7 gilts/pen for each treatment on day 75; 2) the heaviest 10 gilts/pen of each treatment at day 89; 3) the heaviest 10 gilts/pen of each treatment on day 103; and 4) the remaining 7 gilts/pen on day 117. Weights and feed disappearance were recorded every 2 wk and during harvest dates to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (Gain:Feed; G:F). Generalized linear mixed models of SAS were used to analyze all variables. The increase in ADFI over Control gilts was observed 15 d post D2 and continued through 77 d post D2, with advantages in ADG occurring between 15 and 35 d post D2. Control and IMP treated gilts had similar G:F 15 to 33 d post D2. The overall ADG and ADFI from day 0 to market, final live weights, and hot carcass weights were significantly greater (P ≤ 0.05) in IMP gilts compared to Control. When G:F based on live weight was averaged across all groups (i.e., from day 0 to market), T-early had the lowest (P ≤ 0.05) G:F compared to Control, T-medium, and T-late gilts, which did not differ. Carcasses from IMP gilts had increased (P < 0.01) backfat, but similar (P = 0.5) Longissimus muscle depth, compared to Control. Within a cohort of similar aged gilts finishing during the summer, this study indicates that the trajectory of growth is enhanced within a similar window post D2 of IMP. Gilts treated with IMP had heavier carcasses with increased backfat and similar Longissimus muscle depth.

Factors affecting the production of quality ejaculates from boars

Production of acceptable quality ejaculates in boars is dependent upon the Sertoli cell population established before puberty and how effectively these cells function after sexual maturity. In general, factors affecting Sertoli cell mitosis tend to have a two-fold greater effect on sperm production compared with those affecting spermatogenesis. Birthweight is a reliable indicator of in utero testicular development and prepubertal growth rates are positively correlated with testis size and sperm production after sexual maturity. Colostrum intake and pre-weaning nutrition account for much of the variation associated with quality and quantity of ejaculates and represent opportunities to further enhance lifetime sperm production. Interactions between young boars and humans, shortly after weaning, have important effects on spermatogenesis after sexual maturity and need to be studied further. The seasonal effect on depression in semen quality is the most significant factor affecting production of acceptable quality ejaculates after puberty. Ambient temperatures, greater than those of the thermoneutral zone, have both acute and chronic effects that compromise all aspects of the male reproductive axis. Identification of genes associated with heat-tolerant phenotypes holds promise for addressing this challenge, especially in light of the current trend in global warming. Supplementation of vitamins, minerals and other compounds have positive effects on sperm production during periods in which other stressors, especially heat stress, are present and is an important mitigation strategy. Recent information on housing conditions and boar usage patterns indicate these cause relatively minor changes in sperm production, overall, but for some males can have significant, long-term effects.

Effect of immunological castration of male pigs on morphological and functional con-dition of the testicles

Changes in the priorities of the treatment of animals in the conditions of intense technology of production of livestock products are based on the necessity of wellbeing of animals. Therefore, there is a need of search for and broad introduction of generally accepted alternatives to surgery, which would use modern means of castration, particularly immunocastration. The study presents morpho-functional substantiation of practicability of using immunological castration in the conditions of industrial production of pork. At the same time, we studied immunological castration using Improvak on the morphological and physiological condition of the testicles of male pigs. The testosterone level was determined using radioimmunologic method after 2, 4, 6, 8 weeks of immunological and surgical castrations, and also in intact boars of the control group. During the slaughter, we selected biopates of the testicles in immunological castrates and pigs of the control group for histological examination. The testosterone level 2 weeks after castration was the lowest in the animals castrated using Improvak. This indicator gradually increased, and after 8 weeks was higher than in the surgically castrated pigs. In the latter, the level of testosterone gradually decreased for 8 weeks, and did not significantly change in non-castrated pigs. The last stages of spermatogenesis in immunocastrates were inhibited after the second vaccination. As a result of immunological castration, the interstitial tissue of the testicle underwent changes. Between the tubules, a spreading of the loose connective tissue was observed. Leydig cells lost hyper chromaticity of the cytoplasm and typical polygonal profile, and their functional potential decreased. This fact was confirmed by the changes in the Hertwig’s ratio. In particular, we observed decrease in the value of the nuclear-cytoplasmic ratio. There were also a time shift of mitotic cycle, low degree of differentiation of spermatogonia and rupture of the course of the subsequent stages of spermatogenesis. However, there occurred multiplication of primary spermatogonia, single cellular divisions, and in the ductus deferentes, there could be found single spermatids. Some of them formed specific cellular groups of rounded and elliptic shapes in the seminiferous tubules. These structures were absent in the testicles of the control animals. Microstructural changes in the swine after injecting Improvak were characterized by deficiency of Leydig cells, indicating absence of the normal hormonal background, as confirmed by the results of the study of testosterone level. The epithelium-spermatogenic layer was underdeveloped, and the lumens of the tubules were in some places filled with generations of spermatocytes. In some places, meiosis was observed, which also indicates insignificant functioning of the testicles. Vaccination with Improvak caused atrophy of the testicles in swine and decrease in their functional condition, allowing it to be recommended it for broader application as an alternative to surgical castration.

Animal welfare and society concerns finding the missing link

Young adults in developed countries are distanced from agriculture and the meat industry needs to do a better job of communicating with them. A major welfare concern is slaughter without stunning. Other concerns, such as poor stunning or high levels of bruising, can be easily corrected by management who is committed to maintaining high standards. Another concern is biological system overload, occurring when animals are bred for more productivity. Researchers and industry need to determine optimum production levels instead of maximums. Retailers are major drivers of animal welfare standards enforcement and they respond to pressure from both activists and consumers.