Effect of feed restriction on the performance and behaviour of pigs immunologically castrated with Improvac®

Effect of Changes in Dietary Net Energy Concentration on Growth Performance, Fat Deposition, Skatole Production, and Intestinal Morphology in Immunocastrated Male Pigs

Nutritional requirements of heavy immunocastrated (IM) pigs and therefore appropriate feeding strategies have not yet been determined. Thus, the effects of changes in dietary net energy (NE) content were studied in 41 IM pigs, fed ad libitum diets with low, medium, and high NE content (LNE, MNE, and HNE diets, with 8.5, 9.3, and 10.0 MJ NE/kg, respectively), from 84 days of age until slaughter at an average age of 172 days and an average body weight of 122.5 kg. In the period from 143 to 170 days of age, there was a tendency for a greater NE intake (p = 0.08) in pigs fed the HNE diet along with greater (p < 0.01) backfat gain. Dietary treatment affected carcass composition, as lower backfat thickness (p = 0.01) and lower area of fat over the longissimus muscle (p = 0.05) were observed in the LNE and MNE pigs. In addition, greater lean meat content (p = 0.04) was observed in the LNE pigs. Reducing the NE of the diet by replacement of cereals and soybean meal with high-fiber ingredients resulted in lower indole production in the ascending colon (p < 0.01) and greater skatole production (p < 0.01) in the cecum. Greater villus area, width, height and perimeter, crypt depth, and thickness of the intestinal mucosa in the jejunum, ileum, ascending colon, and descending colon were found in the LNE group (p < 0.01) than in the HNE group, while those in the MNE group was intermediate. Cell proliferation was not affected by dietary treatment (p > 0.05). The present results show that a reduction in dietary NE concentration lowers lipid deposition, without affecting performance or energy efficiency in IM pigs. This technique provides an advantage in terms of improved leanness, without affecting growth rate in IM pigs after immunization, which is particularly important when the backfat thickness is a determinant of carcass value and IM pigs are fattened to higher weights (e.g., in heavy pig production) or when a longer delay between immunization and slaughter is practiced.

Increasing the Dietary Concentration of Lupinus albus L. Decreased Feed Intake and Daily Gain of Immunocastrated Male Pigs

Simple Summary

Boar taint is a major cause of consumer complaints about pork but it can be eliminated by immunizing entire males against gonadotrohpin releasing factor (immunocastrated males). However, immunocastrated males have increased feed intake and backfat compared to entire males, which is an issue in countries such as Australia, where producers are penalized for high backfat. The inclusion of an in-feed ingredient, albus lupins, is one way to suppress the voluntary intake of IC male pigs and subsequently their fat deposition, but the appropriate quantity to include in the diet had not been determined. Albus lupins are thought to reduce feed intake due to slower transit of feed through the digestive system, which then influences satiety. The albus lupin concentration to maximize growth rate, minimize feed intake, maximize carcass weight and minimize backfat depth was 120, 142, 62.7 and 138 g/kg, respectively.

Abstract

An experiment was conducted to determine the appropriate dietary concentration of albus lupins that would lower feed intake and decrease backfat while optimizing the effect on the growth rate of immunocastrated male pigs. The pigs were fed albus lupins (varying from 0 to 200 g/kg) from 2 weeks after the last immunization against GnRF for 14 d prior to slaughter (where d 0 is the day of the last immunization against GnRF). Increasing the dietary albus lupin concentration decreased daily gain for d 15 to 28 (p = 0.004). Daily feed intake also decreased as the concentration of the albus lupins increased for d 15 to 28 (p < 0.001). Carcass weight and backfat decreased as the concentration of dietary albus lupins increased (p = 0.011 and p = 0.024, respectively). The albus lupin concentration to maximize growth rate, minimize feed intake, maximize carcass weight and minimize backfat depth was 120, 142, 62.7 and 138 g/kg, respectively.

Strategies to Meet Nutritional Requirements and Reduce Boar Taint in Meat from Entire Male Pigs and Immunocastrates

This paper reviews the current knowledge on the nutritional requirements of entire male and immunocastrated pigs to obtain an efficient growth, low boar taint level, and good carcass and meat quality. We present the reasons for offering entire males ad libitum access to the diets in order to optimize their protein deposition potential. Boar taint is one of the major issues in the production of entire males; therefore, the impact of various skatole- and indole-reducing feed ingredients is discussed regarding their efficiency and the possible mechanism affecting skatole and indole production in the hindgut. Entire males have lean carcasses, so their intramuscular fat content can be lower than that of surgical castrates or females and the adipose tissue can be highly unsaturated. The possible nutritional strategies to counteract these effects are summarized. We conclude that immunocastrates can be fed similarly to entire males until the second vaccination. However, due to the metabolic changes occurring shortly after the second vaccination, the requirements for essential amino acids are markedly lower in immunocastrates than in entire males.

Improvac induces immunocastration by affecting testosterone levels and disrupting spermatogenesis in male broiler chickens

Immunocastration (vaccination against Gonadotropin-releasing hormone (GnRH)) has been regarded as a friendly substitution to physical castration in animals. To date, a few studies have reported the use of Improvac for immunocastration in boar and one study in broiler chickens; however, there is an apparent dearth of scientific evidence regarding the application of Improvac for immunocastration in birds. In the present study, we evaluated the effects of Improvac-based immunocastration on testosterone levels and spermatogenesis in broiler chickens and the effects of Improvac on the expression of genes related to testosterone biosynthesis and metabolism as well as spermatogenesis. The birds were randomly divided into 4 groups (n = 30 each): Control group (non-immunized), Early group (immunized with Improvac at week 3), Late group (immunized with Improvac at week 6), and Early + Late group (immunized with Improvac at weeks 3 and 6). Immunization with Improvac significantly improved the average daily gain compared to the Control group. Of note, following Improvac vaccination, the reproductive efficiency was significantly decreased in male broiler chickens. Furthermore, parameters such as the serum testosterone concentration, spermatogenesis, and the expression levels of genes related to testosterone metabolism (Cyp17A1, Cyp19, HSD3B1, and HSD17B3) and spermatogenesis (Cyclin A1 and Cyclin A2) were significantly reduced in the immunized groups compared to the Control group. Taken together, these findings reveal that immunization against GnRH can be achieved, at least partially, in male broiler chickens. The results of our study also support the hypothesis of using Improvac as an alternative solution to caponization, with considerably improved animal welfare.

Sustainability of Pork Production with Immunocastration in Europe

Immunocastration, a technique to replace surgical castration of piglets, consists of two consecutive vaccinations to induce antibodies which transiently suppress testicular functions and avoid boar taint. It is a method to ensure both a high product quality and a high level of animal welfare. The impact of immunocastration on the three pillars of sustainability has been studied extensively. While all aspects of sustainability have been studied separately, however, a contemporary global overview of different aspects is missing. In immunocastrates, performance results are better than in barrows, but worse than in boars. The environmental impact of pork production with immunocastrates is lower than with barrows, but higher than with boars. The level of aggression is considerably lower in immunocastrates compared to boars. Societal concerns are mainly related to food safety, and are not supported by scientific evidence. After second vaccination, immunocastrates switch from a boar- to a barrow-like status. Therefore, the timing of second vaccination is a fine-tuning tool to balance advantages of boars with environmental and economic benefits against increased risk of welfare problems and boar taint. Nevertheless, both synergic and conflicting relationships between the pillars of sustainability must be communicated along the value chain to produce tailored pork products.

Effect of feed restriction and initial body weight on growth performance, body composition, and hormones in male pigs immunized against gonadotropin-releasing factor

Pigs immunized against gonadotropin-releasing factor (GnRF) have increased carcass fatness compared to entire males; however, the timing of this increase in fatness after the second immunization against GnRF has not been determined. An experiment was conducted to identify and compare the growth performance, body composition, and physiological changes in immunocastrated males (IC males) at different BW and feeding levels. A total of 64 pigs were used in a 2 × 2 × 2 factorial experiment with the treatments being 1) sex (entire males or IC males), 2) initial BW (45.9 kg [light] or 78.3 kg [heavy]), and 3) feeding regime (2.5 times maintenance [restricted] or ad libitum). The pigs were individually housed, and the diets were fed for 4 wk after the second immunization against GnRF until slaughter at either 68.4 kg BW (light) or 105.8 kg BW (heavy). Immunocastrated males on a restricted feed intake had a lower ADG compared to entire males from d 15 to 28 and d 0 to 28 ( 0.011 and 0.011, respectively). Fat deposition was not affected by sex from d 0 to 14, but from d 15 to 28 IC males deposited 45 g/d more fat than entire males ( = 0.025). Immunocastrated male pigs fed ad libitum deposited 87 g/d more fat from d 15 to 28 than entire males fed ad libitum ( = 0.036). However, there was no difference in fat deposition between IC males and entire males when feed intake was restricted from d 15 to 28. Plasma urea nitrogen levels were greater in IC males compared to entire males from d 7 after the second immunization against GnRF ( 0.05 for d 7, 10, 14, 21, and 28). Plasma concentrations of IGF-1 were lower for IC males compared to entire males on d 3, 7, 10, and 28 ( 0.05 for all days). The following conclusions were made: 1) when pigs are immunized at a light BW (50 kg) and/or are on a restricted feed intake, they have a reduced propensity to deposit fat; however, the restriction in feed intake adversely affects growth rate. 2) The majority of fat deposition for males immunized at heavy BW (80 kg) occurs from d 15 to 28 after the second immunization against GnRF.

The Effect of Lupinus albus on Growth Performance, Body Composition and Satiety Hormones of Male Pigs Immunized against Gonadotrophin Releasing Factor

Two hundred and ninety four pigs were used with the aim to develop a dietary management strategy using Lupinus albus L. (albus lupins) to reduce the increase in feed intake and subsequent increase in carcass fatness in pigs immunized against gonadotrophin releasing factor (immunocastrates; IC males) and entire male pigs in the late finishing stage. From day (d) 0 to 28, IC males fed the control diet grew faster (p = 0.009) than entire males fed the control diet but there was no difference in growth rate between sexes for pigs fed albus lupins for 14 days pre-slaughter (Albus 14) or pigs fed albus lupins for 28 days pre-slaughter (Albus 28). From d 15 to 28, IC males receiving the Albus 14 diet grew more slowly (p < 0.001) than entire males receiving the Albus 14 diet. From d 15 to 28 (p < 0.001), IC males fed the control diet ate more feed than entire males fed the control diet, although there was no difference between sexes in feed intake of the Albus 14 and Albus 28 diet. Immunocastrates had a lower backfat when fed either Albus 14 or Albus 28 compared to the control diet, although there was no difference between diets for entire males. There was also a trend for pigs on the Albus 14 and Albus 28 diets to have a higher lean deposition (p = 0.055) and a lower fat deposition (p = 0.056) compared to the pigs on the control diet. Pigs fed the Albus 28 diet had a lower plasma ghrelin concentration compared to pigs fed the Albus 14 or the control diet (p = 0.002). Pigs fed the Albus 28 diet had a higher peptide YY concentration than those fed the control or albus 14 diet (p = 0.004). The inclusion of albus lupins at 20% in the diets of IC male pigs for either 14 or 28 days pre-slaughter was successful in reducing feed intake, body fat and backfat to similar levels of entire males. However, the growth rate of the IC male pigs was impacted more than would be desirable.

The Effect of Lupinus albus and Calcium Chloride on Growth Performance, Body Composition, Plasma Biochemistry and Meat Quality of Male Pigs Immunized Against Gonadotrophin Releasing Factor

Simple Summary

Pigs immunized against gonadotrophin releasing factor (immunocastrated (IC) males) have an increased feed intake, growth rate, back fat and fat deposition compared to entire males. It is desirable to develop management strategies to limit the increase in feed intake and fat deposition in IC males. This experiment used in-feed ingredients (Lupinus albus (albus lupins) or a combination of calcium chloride and sodium tri-polyphosphate (mineral salts)) to try to suppress the voluntary feed intake of IC male pigs and subsequently fat deposition. Mineral salts decreased feed intake with no effect on fat deposition while albus lupins reduced both feed intake and fat deposition in pigs.

Abstract

Two hundred and ninety-four pigs were used to assess the effect of two ingredients (Lupinus albus (albus lupins) or a combination of calcium chloride and sodium tri-polyphosphate (mineral salts)) on growth performance, body composition and objective meat quality of pigs immunized against gonadotrophin releasing factor (immunocastrates) and entire male pigs in the late finishing phase. Pigs fed mineral salts ate less feed than those fed the control diet with no effect on growth rate (p > 0.05), backfat (p > 0.05) or fat deposition (p > 0.05). Pigs fed albus lupins had a reduced feed intake (p < 0.001 for all time periods), lower growth rate (p < 0.001 for all time periods), lower backfat (p < 0.005) and decreased fat deposition (p < 0.001 for all time periods) compared to those fed the control diet or mineral salts. From day (d) 0–28 pigs fed mineral salts had a better feed conversion ratio (p = 0.001) than those fed albus lupins who in turn had an improved feed conversion compared to the control diet. Immunocastrates had thicker backfat than entire males at the end of the experiment (p < 0.001), however, feeding albus lupins to immunocastrated males reduced backfat thickness to similar to entire males fed the control diet (p = 0.01). With the exception of the increased muscle pH at 45 min post-exsanguination in mineral salts and albus lupins compared with the control diet (p = 0.03) there was no effect of diet on objective pork quality. Pork from IC males had a higher ultimate pH (p < 0.001), was lighter (L*; p = 0.003), more yellow (p = 0.008) and had a higher drip loss (p < 0.001) compared to entire males. Albus lupins show potential in reducing the increase in feed intake and backfat associated with immunocastration. Mineral salts may be useful in situations where a reduction in feed intake and an improvement in feed conversion is desired and reducing fat deposition is not the objective.

Lysine requirement for growing-finishing immunocastrated male pigs

Eighty boars (19.3 ± 2.49 kg) were vaccinated twice (100 and 128 days of age) against gonadotropin releasing hormone (Vivax™ vaccine), for a randomised block design study aiming to evaluate five digestible lysine (DLys) level treatments, with three phase-feeding per treatments (9-8-7; 10-9-8; 11-10-9; 12-11-10 and 13-12-11 g/kg) during the growing-finishing phases (54-100, 100-128 and 128-155 days of age, respectively). Pigs were fed their respective diets ad libitum from 54 to 155 days and weighed at 100, 128 and 155 days. Pig loin (Longissimus dorsi) area, loin depth and backfat thickness were measured by ultrasound at 100 and 155 days. Hot carcass weight, meat quantity and meat yield were measured at slaughter. From 54 to 100 days (pre-immunocastration), DLys levels linearly improved pig feed conversion and loin area, the level of DLys for minimum feed conversion and maximum loin area was 13 g/kg. However, DLys levels had no effect on the performance of boars from 54 to 128 days (pre-immunocastration), nor on the performance and carcass parameters of immunocastrated male pigs between 54 and 155 days. A sequence of diets containing 9, 8 and 7 g/kg of DLys fed from 54 to 100, 100 to 128 and 128 to 155 days, respectively, meet the requirement of growing-finishing immunocastrated male pigs.