Panel examines benefit of immunological castration

Panel examines benefit of immunological castration

ZOETIS recently commissioned a panel of nutritionists, meat scientists and economists to examine the nutritional benefits associated with raising male pigs in a program using immunological castration (IC) — specifically IMPROVEST gonadotropin releasing factor analog-diptheria toxoid conjugate — compared with physical castration (PC) in North American production systems.

The panel referenced the Zoetis "Global Nutritional Guidelines" as the foundation for studying the effect of immunization to manage off odors and to establish nutrient requirements for male pigs under this program.

Zoetis provided Feedstuffs with a summary of the panel's findings, which included the following points:

* Capturing inherent advantages of raising intact male pigs. Male pigs are given IMPROVEST in the finishing phase, eliminating the need for physical castration early in life. As a result, male pigs are able to fully express their natural potential for feed-efficient growth, with all of the inherent performance advantages of intact males for the majority of the production cycle, the panel said.

Of importance, a two-dose regimen is used, meaning different nutrient requirements are needed prior to and after the second immunization to optimize pig performance, the group said.

* Nutritional impact associated with two distinct growth phases. The existence of two metabolic phases — before and after the second immunization — offers opportunities for optimizing production efficiency and carcass characteristics, the panel explained.

The first dose is administered after nine weeks of age to prime the immunological system of the male pig. During this period, intact males consume less feed, grow slightly more slowly and deposit more body protein (i.e., lean tissue) than pigs that have been physically castrated earlier in life, Daniel Nelson, a nutritionist with Zoetis, told Feedstuffs.

The second dose is administered at least four weeks after the first dose and between three and 10 weeks before the pig is marketed. This second dose temporarily suppresses testicular function as pigs transition to a barrow-like physiology and metabolism for the last few weeks of the finishing period.

Nelson said during this phase, male pigs begin to eat substantially more feed per pound of gain and increase the amount of fat in the carcass, thus attaining a desirable fat level for primal cut characteristics. This allows those pigs to increase fat levels, which is important to preserving belly quality.

* Intact males have slightly higher lysine requirements. Dietary requirements for lysine, minerals and vitamins are higher for intact males (or IC barrows until dose 2) than for gilts, the panel found. About seven days after dose 2, lysine levels for IC barrows can be substantially reduced because of increased feed intake. The Table outlines recommended dietary levels of lysine and other critical nutrients.

* Trials uncover nutritional advantages and value to producers. The expert panel quantified three nutritional advantages with immunological castration that allow producers to capture the most value from this technology, including:

1. IC barrows demonstrated a feed conversion ratio 8.41% lower than PC barrows.

2. IC barrows held a 4.28% average daily gain advantage over PC barrows.

3. IC barrows were 10-12 lb. heavier at market, with a 4-6 lb. heavier carcass at the same number of days to market as PC barrows.

In addition, the panel examined other topics of interest to the North American pork industry to ensure that the benefits of immunization can be optimized in all systems where it will be adopted, including:

* Producers feeding dried distillers grains to IC barrows and using a withdrawal period of five to seven weeks prior to slaughter are expected to harvest bellies with superior fat characteristics compared with PC barrows. The panel credited this to the higher feed intake of IC barrows after the second immunization and consequent higher body fat deposition rates that result in a more saturated fatty acid profile.

Producers who wait longer to market pigs after dose 2 will not lose the feed efficiency advantage gained in the preceding 10 weeks, the panel said. Even after the second dose, the feed efficiency of IC barrows will remain superior to PC barrows. This allows producers to market more pounds of pork with similar feed costs, thereby increasing revenues relative to costs.

* Recent studies confirmed that ractopamine has an additive effect on the growth performance and feed efficiency of IC barrows. Therefore, ractopamine should be fed according to manufacturers' instructions, noted Mark Bertram, a consultant with First Choice Livestock LLC and panel chair.


Recommended dietary levels of lysine (%) and other nutrients for pigs raised using IMPROVEST versus gilts


-Lysine (%) at weight ranges-


55-110 lb.

111-165 lb.

166-220 lb.

221-286 lb.






IC barrow





Notes: Adjust other nutrients (other amino acids, minerals such as phosphorus, vitamins) in proportion to lysine. After second immunization, increase threonine:lysine to reflect increased feed intake (61-66% of lysine). No interaction with ractopamine; effects appear to be additive. Gilts were used as the baseline for comparison because there are few published data comparing the protein or lysine requirements of contemporary intact males and barrows.

*IC barrow value may be higher.


FSIS status

In another development related to IMPROVEST, the U.S. Department of Agriculture's Food Safety & Inspection Service (FSIS) recently issued a directive regarding on-farm protocols for using IMPROVEST. This protocol accreditation helps ensure operational consistency for packers and their producer suppliers who adopt IMPROVEST that product protocols are comprehensive and will remain stable over time, according to Zoetis.

The previous FSIS "notice" acknowledged that hogs presented at harvesting facilities with the IMPROVEST quality assurance certificate are to be classified as barrows and, therefore, do not warrant testing for off odors during inspection. Changing the classification to a "directive" signals that protocols for using IMPROVEST are no longer subject to annual review, although Zoetis said it will continue to audit and refine those protocols as necessary.

"It's important that our processes for using IMPROVEST meet the highest standards on the farm and at the processing plant," said Gloria Basse, vice president of Zoetis' U.S. Pork Business Unit. "As we continue to work with packers on processing pigs raised using IMPROVEST, this FSIS status upgrade further validates IMPROVEST as a production option for the entire pork industry."


Pig toys

In cooperation with Kassel University, WEDA Dammann & Westerkamp, a company in Lutten, Germany, that specializes in pig house equipment, has developed a new kind of manipulatable material for piglets and finishing pigs.

Using rooting cones and pushing balls of bite-resistant and food-safe polyurethane mounted to the floor and brackets, the animals can act out their natural play instinct and can busy themselves while standing up, sitting or lying down, an announcement said.

The cones have been tested in various pig houses and showed consistently positive results. In particular, "re-orientated" behavior patterns like tail biting were reduced when the pigs were able to satisfy their rooting instinct.

Scientific findings have also demonstrated the practical suitability of the toys: in test groups with rooting cones, the animals used the cone significantly more frequently than animals in the comparison group with the classical chain or ball. Consequently, the atmosphere in the rooting cone groups was more tranquil than in the comparison groups, the result being that injuries visibly declined as well. The results of this so-called "screening" (visible scratch marks) were taken into account during product development, WEDA said.

The rooting cone comes in a 60 mm diameter for piglets or an 80 mm diameter for finishing pigs. The balls are mounted on a stable plastic ground plate with flexible metal springs so the movements of the balls ensure variety and resistance, and the animals remain in the center of the house instead of in corners, WEDA said.

The pushing balls were developed in direct connection with the rooting cones.

"We were well aware of the demand of pig farmers for suitable manipulatable material, especially for the farrowing section and service station," explained WEDA development manager Ralf Meyer.


Genetic potential

Pigs fall well short of their genetic potential in today's production system, which costs the industry millions of dollars in lost performance, according to a swine nutrition expert with Novus International.

Dr. Jeffery Escobar, senior manager of swine research at Novus, told a group of European producers visiting the company's headquarters in St. Louis, Mo., that despite various improvements in production efficiency, the industry does not capitalize on the full genetic potential of animals.

"There remains a vast gap between swine performance on a conventional farm and performance in a facility that is more aseptic and perhaps targeted towards research. That clearly indicates that we are way below the ceiling for the genetic potential for performance of animals," Escobar said.

"If animals are removed from conventional farm facilities and placed into an ultra-clean facility optimized for air quality, water purity, feed mix, environment, manure management and disinfection, then performance can significantly improve," he added. "What the gap illustrates is that there is progress we can make to achieve better performance by improving nutrition, management, environment and all other aspects that contribute to expressing or repressing the genetic potential of animals."

While Escobar said growing animals in such a clean environment on a full production site may be unrealistic, producers can get closer to the goal of reaching the animals' full genetic potential.

One way to improve that performance is to optimize animal feed to ensure that individual animals are receiving the ideal amount of nutrients. 

Volume:85 Issue:48

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