A gonadotropin-releasing factor vaccine (Improvac) and porcine somatotropin have synergistic and additive effects on growth performance in group-housed boars and gilts1,2

A total of 48 Duroc × (Landrace × Large White) gilts of 33.2 kg BW were used to investigate the influence of immunocastration and diet on growth performance and carcass, meat and fat quality. Four treatments were arranged factorially (2 × 2) with two sexes (immunocastrated gilts: IG v. entire gilts: EG) and two dietary treatments (a commercial feedstuff as control v. granulated barley as a single major ingredient) provided during the finishing period (from 103 to 126 kg BW). There were four replicates of three pigs per treatment. At the end of the trial, the IGs grew faster ( P < 0.05) and ate more feed ( P < 0.05) than the EGs. Carcasses from the IGs had thicker backfat depth than those from the EGs ( P < 0.01) and carried out a lower percentage of rejected carcasses ( P < 0.05) at slaughterhouse owing to lack of fat. Meat from the IGs tended to have higher intramuscular fat (IMF) content in the Longissimus thoracis (LT) muscle than that from the EGs ( P = 0.09). In addition, immunocastration increased the total saturated fatty-acid proportion in subcutaneous fat and IMF ( P < 0.001) and decreased the total monounsaturated fatty acid (MUFA) and total polyunsaturated fatty acid (PUFA) percentages in subcutaneous backfat ( P < 0.05 and P < 0.001, respectively) and in IMF ( P < 0.01 and P = 0.06, respectively). The use of a diet based on granulated barley during the finishing period had no effect on growth performance but tended to increase IMF content in the LT muscle ( P < 0.06), and increased MUFA ( P < 0.05) and decreased PUFA ( P < 0.01) proportions in omental fat. It is concluded that immunocastration of gilts intended for dry-cured ham industry improved some aspects of growth performance and carcass and meat quality, whereas granulated barley had scarce effect on productive traits and fatty-acid profile but tended to improve IMF content.

Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 98%

The effect of immunocastration and a diet based on granulated barley on growth performance and carcass, meat and fat quality in heavy gilts

Daza

Latorre

Olivares

et al. 2014

“…Immunization against GnRF is an alternative method of inhibiting sexual Nutritional requirements of anti-GnRF immunized boars 1771 development and aggressive behaviours in the late finisher phase and reducing the accumulation of boar taint compounds in carcass fat. This results in a reduction in plasma gonadotrophins and testosterone (Bonneau et al, 1994;Dunshea et al, 2001;McCauley et al, 2003;Oliver et al, 2003). The reduction in testosterone as a result of immunization against GnRF has a profound effect upon behaviour (Rydhmer et al, 2010).…”

Section: Resultsmentioning

confidence: 99%

The effect of immunization against GnRF on nutrient requirements of male pigs: a review

Dunshea

Allison

Bertram³

et al. 2013

In most countries, male pigs are physically castrated soon after birth to reduce the risk of boar taint and to avoid behaviours such as fighting and mounting. However, entire male pigs are more feed efficient and deposit less fat than barrows. In addition, many animal welfare organizations are lobbying for a cessation of castration, with a likelihood that this could lead to inferior pork unless an alternative method is used to control boar taint. An alternative to physical castration is immunization against gonadotrophin releasing factor (GnRF) which allows producers to capitalize on the superior feed efficiency and carcass characteristics of boars without the risk of boar taint. From a physiological perspective, immunized pigs are entire males until shortly after the second dose, typically given 4 to 6 weeks before slaughter. Following full immunization, there is a temporary suppression of testicular function and a hormonal status that resembles that of a barrow. Nutrient requirements will be different in these two phases, before and after full immunization. Given that there have been few published studies comparing the lysine requirements of entire males and barrows in contemporary genotypes, it is useful to use gilt requirements as a benchmark. A series of meta-analyses comparing anti-GnRF immunized boars and physical castrates and use of nutritional models suggest that the lysine requirement of entire males before the second immunization is 5% higher than for gilts, from 25 to 50 kg BW, and by 8% from 50 to 95 kg. Given that the penalty in growth performance for having inadequate dietary lysine is greater in males than in gilts or barrows, it is important to ensure that lysine requirements are met to obtain the maximum benefits of entire male production during this phase. After the second immunization, the lysine requirement of immunized males decreases and may become more like that of barrows. In addition, a consistent effect of full immunization is a marked increase in voluntary feed intake from about 10 days after the second dose. Putting these together, the estimated lysine requirement, expressed in terms of diet composition, falls to 94% of the gilt level. Although general principles can be described now, further research is needed to fully define the lysine requirements of immunized boars. It is important that the temporal pattern of tissue deposition rates and feed intake be explored to be incorporated into models to predict nutrient requirements over the period of rapidly changing metabolism.Keywords: finishing pigs, growth, boars, nutritional requirements, immunological castration. ImplicationsMale pigs immunized against gonadotrophin releasing factor are physiologically entire males for most of their life and as such they should be fed as entire males at least up until the second immunization. Shortly after that time, testicular function is suppressed and the hormonal and metabolic status rapidly adjusts to resemble that of a physical castrate. As a consequence, feed intake and tissue deposition ch...

“…Australia) and comparisons have been made with entire males. An experiment conducted by Oliver et al (2003) gives interesting indications concerning the performance of immunocastrates and entire males, although its aim was to determine the consequence of the use of Improvac R combined with daily injections of porcine somatropin.…”

Section: Immunocastrationmentioning

confidence: 99%

Resource efficiency and economic implications of alternatives to surgical castration without anaesthesia

Roest

Montanari

Fowler

et al. 2009

This paper presents an analysis of the economic implications of alternative methods to surgical castration without anaesthesia. Detailed research results on the economic implications of four different alternatives are reported: castration with local anaesthesia, castration with general anaesthesia, immunocastration and raising entire males. The first three alternatives have been assessed for their impact on pig production costs in the most important pig-producing Member States of the EU. The findings on castration with anaesthesia show that cost differences among farms increase if the anaesthesia cannot be administered by farmers and when the veterinarian has to be called to perform it. The cost of veterinarian service largely affects the total average costs, making this solution economically less feasible in small-scale pig farms. In all other farms, the impact on production costs of local anaesthesia is however limited and does not exceed 1 hct per kg. General anaesthesia administered by inhalation or injection of Ketamin in combination with a sedative (Azaperone, Midazolan) is more expensive. These costs depend heavily on farm size, as the inhalation equipment has to be depreciated on the largest number of pigs possible. The overall costs of immunocastration -including the cost of the work load for the farmer -has to be evaluated against the potential benefits derived from higher daily weight gain and feed efficiency in comparison with surgical castrates. The economic feasibility of this practice will finally depend on the price of the vaccine and on consumer acceptance of immunocastration. The improvement in feed efficiency may compensate almost entirely for the cost of vaccination. The main advantages linked to raising entire males are due to the higher efficiency of feed conversion, to the better growth rate and to the higher leanness of carcass. A higher risk of boar taint on the slaughter line has to be accounted for. Raising entire males should not generate more than 2.5% of boar taint among slaughter pigs, in order to maintain the considerable economic benefits of better feed efficiency of entire males with respect to castrates.