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Nutrition Was Key Topic at UK Turkey Conference

by 5m Editor
5 May 2010, at 12:00am

Five papers at this year's Turkey Science and Production Conference covered the most important topic of nutrition. For ThePoultrySite, editor Jackie Linden, selects the highlights.


In his welcome presentation at the fourth Turkey Science and Production Conference in Macclesfield earlier this year, organiser Dr James Bentley expressed his pleasure at the record number of delegates at the event as well as the high standard of the papers.

In all, there were almost 200 delegates from 23 different countries and on the programme were 19 papers covering health/disease, nutrition, practical management and marketing of the final product. The record number of commercial sponsors of the event is also testament to the support provided to this tight-knit industry.

Feeding Techniques for Turkey Breeders

Continually striving to develop a bird that will deliver the optimum performance package, turkey breeders have been improving health traits as well as weight and breast meat potential in the commercial product and egg production and hatchability in the parent stock, explained Dr Peter Woodward of Aviagen Turkeys at the start of his presentation. For both male and female lines, this requires some control of bodyweight, albeit not to the extent of broiler breeders, he said.

Control of female bodyweight

Full feeding of turkey breeder hens from a medium or a heavy line would result in poor egg production and an increase in mortality from problems such as prolapse and egg peritonitis, explained Dr Woodward. He continued that it is necessary to control growth, and particularly the amount of fat in the abdominal cavity, by restricting feed intake by females in quantitative or qualitative terms.

Outlining these two restriction methods, he went on to discuss timed feeding and skip-a-day feeding programmes. Turkey breeder hen weight can be controlled to a target using several different techniques, he said, adding that Aviagen has invested heavily in research to gain a better understanding of the developmental requirements of Nicholas female parent lines. Work is currently underway in Europe to relate developmental profiles to egg production.

For the females, Dr Woodward concluded that it is important for hens to be in a physiologically positive status at the end of the rearing stage so that they can respond to photostimulation, whilst having enough reserves to support the birds through any natural periods of weight loss.

Control of male bodyweight

Turning his attention to turkey males, Dr Woodward highlighted the practical difficulty in simultaneously controlling the weight of males and females in a mixed group from an early age and with a single feeding system. Males have a much higher protein requirement during the starter phase than the females, for example. However, it is just as important to control the bodyweight of the males as overly heavy males produce less semen, are more difficult to handle and have higher mortality. In allow the development of the best males before final selection, it is important to match the males' body weigh to the target, as for the females.

Dr Woodward went on to outline qualitative and quantitative restriction techniques for male turkeys, offering guidelines for controlled feeding starting at 20 or 29 weeks of age.

Conclusions

He concluded that control of weight development of breeders is necessary to exploit the genetic potential of today's strains. Males benefit from some level of quantitative restriction, while female lines can currently be brought into production by feeding low-density diets, said Dr Woodward.

Looking to the future, Dr Woodward raised the prospect of the need to control females bodyweight through quantitative restriction. He warned that this will require the industry to make significant investment in feeding equipment. In the meantime, he added, the breeding companies will invest further in developing understanding of the nutrient requirements of their birds for optimum performance.

Other Papers on Nutrition and Feeding

Use of guanidino acetic acid in all-vegetable diet for turkeys

Dr Andreas Lemme of Evonik-Degussa in Germany reported three experiments in which turkeys diets were supplemented with guanidino acetic acid (GAA; CreAmino). He explained that GAA is the natural precursor of creatine in the metabolism of many animals, including poultry. Creatine and GAA are found in animal products but it has been hypothesised that they may be limiting turkey performance in today's all-vegetable diets.

Summarising the experiments he presented, Dr Lemme said that the results indicate supplemental GAA is effective in turkey nutrition, confirming previous findings in broilers. The most consistently improved parameter was feed conversion, implying that GAA improves the utilisation of dietary nutrients, and possibly that GAA has its effect by stimulating energy metabolism through creatine.

Efficacy of organic minerals in turkey diets

In opening his presentation, Dr Curtis Novak of Land O'Lakes Purina Feeds in Kansas City, USA, said that trace mineral nutrition of turkeys has been largely neglected in the last 20 or more years, yet modern turkeys are very different from their predecessors of previous decades. He highlighted that breeding companies and commercial turkey producers tend to use higher levels of manganese, zinc, iron, copper and selenium than those given in earlier reference sources, including the NRC requirements published in 1994. Furthermore, feed formulations have changed over the years and new feed additives, such as phytase, commonly used in modern diets were unheard of when the so-called 'book requirements' were set.

Little work has been done with turkeys, he explained. However, he noted that supplementing a breeder diet with zinc methionine improved the immune function of the progeny compared to zinc sulphate, and progeny tibia weight and bone zinc content were higher than with zinc oxide. Furthermore, T-cell activity (a measure of immune function) was improved when zinc was supplemented in the diet as the methionine complex compared with zinc sulphate.

Dr Novak concluded that the use of organic minerals are good sources of these nutrients, and that they could be used commercially to reduce reliance on inorganic minerals, while maintaining performance, increasing immune function and protecting the environment by reducing the excretion of trace minerals.

Role of mycotoxins in causing leg weakness

In a review paper, Andrew Robertson of Biomin summarised the effects of the various groups of mycotoxins, citing several examples of the effects of these toxins on the general health of turkeys and on leg problems in particular.

He highlighted particularly that tibial dyschondroplasia, articular gout, rickets and deficiencies of calcium and phosphorus are very real consequences of mycotoxin contamination of the diet. The potential for problems is further increased by the combined effects of multiple mycotoxins – as often found in practice – and the possibility of indirect effects on immune suppression.

Mr Robertson emphasised the need to minimise fungal infections and the development of mycotoxins at all stages of production from field to feed trough. He added that the combination of mycotoxin binders plus bio-transformation along with bio-protection through plant and algal extracts, for immune stimulation and liver protection, give the most complete security for the protection of turkeys against leg weakness caused by mycotoxins.

Amino acid digestibilities in feed ingredients for turkeys

As with the previous speakers, Dr Ariane Helmbrecht commented that while ileal amino acid digestibilities in feed ingredients for broiler feeds have been extensively investigated, there have been few studies in turkeys. At this conference, she reported her work with researchers at the University of Warmia and Mazury in Poland. They used four-week-old male turkeys and assessed the ileal digestibility of amino acids in soybean meal, peas, yellow lupins, rapeseed meal and sunflower meal.

From the results, she concluded that there are some significant differences in ileal amino acid digestibility between the two species, and so it is not appropriate to extrapolate values obtained in broilers to turkeys.

May 2010