Reducing protein levels makes the feed less expensive but also causes a reduction in performance. Increasing protein will improve performance but make the diet more expensive. Profitability depends on the cost of feed and the income generated from sales. The optimal diet will be different for each production operation depending on the circumstances. The consequences of changing diets can be predicted by using this data.

Ross calculated the change in profitability (margin) due to altering the protein level in the diet. It is calculated for four production situations; broiler growing, broiler integration with no portioning, 50% portioning and 100% portioning. Figure 2 shows the effect of changing protein level within each production situation. Profitability for each production situation is shown relative to the level of protein recommended in the manual, which is expressed as 100.

It is not possible to compare absolute profitability between situations using figure 2, which shows very clearly how dietary protein level influences the profitability. Broiler growing appears to be relatively more sensitive to changes in protein level than integrated operations. This is a result of the combined effects of liveweight, FCR and feed cost which determine the profitability in a broiler growing operation. Integrated operations are affected by processing performance and resulting incomes, which seem to be relatively less sensitive to changes in protein level.

These data suggest that margins in integrated operations do not reach a maximum in the range analysed although there is a diminishing return above the recommended protein level. The continuing increase in profitability at higher levels of protein is driven by the increased yields seen with high levels of protein in these trials. Profitability for integrated operations with high levels of portioning is more sensitive to dietary protein level. This is due to the greater responsiveness of high value portions compared to eviscerated carcasses.

This is a "unique" solution for a standard set of conditions. Should protein be relatively more ‘expensive’ than in Europe, there is likely to be a more rapid decline in profitability above recommended levels. This is caused by the increasing cost of producing high protein diets while yield has reached its plateau.

In conclusion, the economic analysis shows that the whole production process must be examined to determine the optimal protein level to maximise profits. Reducing feed costs may make the cost side of the equation look good but the resulting loss in growth, FCR and yield will have negative effects on profitability. As costs and incomes change and in different types of operation, the optimum protein level to maximise profit will change.

Antibiotic Growth Promoters

Antibiotic Growth Promoters (AGP) are widely used in monogastric diets in order to improve growth and performance. Their mode of action is through the modification of the intestinal flora of the animal. Most target Gram positive organisms (Clostridium and Streptococcal bacteria) which are associated with poorer health and performance of the animal. By reducing microbial destruction of essential nutrients, increased synthesis of vitamins and other growth factors occur. The intestinal wall becomes thinner and enhanced absorption and utilisation of nutrients occur. AGP’s are absorbed minimally from the gut and do not have a systemic action. There is therefore no risk of residues in the meat.

The response of animals to AGP’s is variable and this is probably dependent upon the environment in which they are raised and the diet that they are offered. As AGP's exert little or no benefits on the performance of germ free animals, it is clear that their effect is related to their antimicrobial activity rather than being caused by direct interaction with the physiology of the animal.

The presence of intestinal microflora is thought to reduce animal efficiency through the following mechanisms (Bedford, 2000):

In addition to their growth promoting role, they are known to control such clinical diseases as necrotic enteritis and cholaniohepatitis (caused by Clostridium perfringes).

Research using semi-synthetic diets has shown that the "energy cost" of the gut microflora in broilers was at least 10% of the total AME. Estimates using pooled data (Rosen, 1995) would suggest that the average benefit of feeding AGP's such as bacitracin, is an improvement of FCR of approximately 3%, with a range of 0 to 5%. Data published by Ross Breeders (Ross Tech 99/37) is more comprehensive.

The routine use of AGP's in poultry feed is coming under close scrutiny due to the concern of bacterial resistance (the scientific community) and general health reason (the consumer). If any product is used for an extended period, some bacteria will attain resistance and so proliferate in the bird. Thus AGP’s tend to become less efficient over time and thus shuttling of products to use a different product every 6 months or so is now standard practice.

The transfer of the "resistance" factor from one microbe to another is becoming of greater concern in human medicine. It is for this reason that the use of AGP’s has now been banned in the EU.

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As you may remember from our last newsletter our nutritionist in training, Steve Kyriazis, is currently gaining some farming experience at Kanhym’s Middleburg farm. He has been running the Artificial insemination (AI) station for a while and has sent us the following contribution.

AI has proven to be a contentious topic of discussion over the last couple of months. Many farmers have opened up to the possible benefits of AI and have put themselves at the mercy of those "in the know". To the average farmer, AI does hold some very real benefits in terms of top quality genetics, and the speed with which these genes are manifest in one’s herd. There are also health and ease of management pros, as well as some significant returns in terms of weight gains and carcass grading as a result of the superior genes entering the fold. The problem is that the practical application of this simple and effective technique has proven a little trickier than expected because of some key factors that need to be heeded in order to achieve maximum returns.

Here are some suggestions that might help one succeed:

Provided all is well in the boar house and management is sound, the laboratory and its procedures are the beginnings of success, or failure. Boar semen is sensitive to fluctuations in temperature and correct control in the lab are an absolute necessity:

Semen must be cooled as fast as possible after collection and dilution, in order to slow the sperm-metabolic rate. This causes a reduction in its usage of its limited nutrient resources (from the extender).

The cooler the semen, the longer its shelf life. The optimum temperature for storage is between 16º and 17ºC. Below 15ºC the sperm suffer from cold shock and never recover, while above 20ºC sees an increase in the metabolic rate. Causing sperm to use nutrient reserves too quickly, thus shortening their storage life and efficacy.

The transport of semen is an important step in the chain of events. Long distance transport necessitates the use of thermostatically controlled coolers while for shorter distances the use of a good quality cooler box (with ice bricks) is adequate. A storage facility on the farm should be equipped to maintain correct temperatures indefinitely (never in a fridge where temperatures drop to 5-8ºC). Semen tends to settle in the bottom of the sachet, which causes the sperm to use up the nutrients in the immediate vicinity. Inverting the sachet gently will remix the semen and evenly spread it throughout the sachet.

Heat detection and stimulation is important when using AI. The use of a vasectomised boar and time spent watching sows and gilts for signs of oestrous are important and must be performed to the best of one’s ability. When preparing to inseminate, remove only the semen required from the cooler. This prevents semen from spending long times at the incorrect temperature or in the sunlight. Semen should be brought to body temperature gradually using ones body heat. Sperm must be handled with care so as not to cause any physical damage.

AI is a technique that requires a fair deal of precision on the part of both semen producer, and the farmer using AI. The process of successfully applying the AI method to ones herd depends on many factors and in the final analysis only good teamwork will yield the desired results.

During the work that I carried out towards my Phd degree we conducted a study to better understand the dynamics involved in water use and quality in agriculture. The idea was to examine the validity of existing water quality guidelines in their application to South Africa’s unique circumstances.

Data and maps of the distribution of groundwater sampling points where water constituent levels exceeded the recommended maximum over the last five years, where obtained from the Directorate: Geohydrology of the Department of Water Affairs and Forestry (Map 1).

With reference to the above information, an experiment was conducted where different levels of Calcium in the drinking water were tested. Commercial diets were fed to these birds, the only variable being different Calcium levels in the water.

Images from the scanning electron microscope taken from the eggshells in the above two treatments are shown in Figures 1 and 2. As can be seen, the shells of hens receiving 200 mg/l of Calcium are much more compact and the higher breaking strength can therefore be understood.

Egg receiving 200 mg/l of added Calcium to the drinking water (outer shell to the left).

These Pictures have been removed because it is to big if you would like them please contact us.

Zearalenone is a resorcyclic acid lactone compound with estrogenic properties and it is capable of binding to oestrogen receptors. Pigs are particularly susceptible to Zearalenone toxicity which elicit the following hyperestogenism toxicity signs (Etienne and Dourmand 1994):

Pre pubertal gilts: Reddening and swelling of the vulva, increased size of the uterus, mammary enlargement, and rectal and vaginal prolapse.

Boars: Testis atrophy, nipple enlargement, and rectal prolapse.

Mature sows: Prolonged oestrus, ovarian atrophy, pseudopregnancy, abortion, increased embryonic mortality, stillbirths, and birth of weak piglets often suffering from straddle leg.

Toxic levels: Pigs are very sensitive to Zearalenone and within the species, prepubertal gilts seem most sensitive (Dickman and Green, 1992).

Zearalenone toxins are often present in feed as indicated by the commonly swollen and reddened vulvas in prepubertal gilts, which is sometimes even seen in new-born litters. The widespread presence of Zearalenone contamination is also confirmed in tests conducted by the Maize Trust Out of 57 samples tested during the 2001-harvesting season, 55 contained traces of Zearalenone (<0.1 ppm) while only 2 samples contained more than 0.1 –ppm Zearalenone.

The cost of Zearalenone toxicity to the pig industry is difficult to access. The only tangible cost is the direct expenditure on Mycotoxin binders. Production losses caused by Zearalenone are impossible to determine – these losses are probably confined to units using mouldy ingredients or having poor grain or feed storage facilities. The reasons why reproduction losses from Zearalenone are believed to be small are as follows: