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TRACE MINERALS FOR SOWS - A NEW APPROACH Dr. Brian Hardy NutriVision Inc BackgroundFemale pigs derived from genetic improvement programs that have been designed to improve body protein mass do not reach mature body size until 200-250 kg in weight or 4-5th parity. Selection to increase prolificacy tends to put high demands on the young female during parity 1-3. These leaner sows tend to have lower feed intakes, resulting in the need to increase nutrient concentration in diets. Nutrient input must be adequate at all times to support maternal body growth, development of the large litter in utero and the necessary level of milk output to achieve good weaning weights. Whenever this is not achieved the sow has to draw on her own body tissues to make up for any dietary deficit. This is normally seen as a loss in body condition, elongated wean to oestrus interval, poorer conception and farrowing rate and smaller subsequent litter sizes. The main reasons recorded for culling sows is poor reproductive performance and inferior leg or foot condition. This often occurs by parity 3-4 and results in a replacement rate of 45-60% in many herds. This represents a great loss of productivity and increases the overhead cost of the breeding unit. Over recent years, sow research has concentrated on the requirements for energy, amino acids, calcium, phosphorus and chromium. Nowadays, most nutritionists formulate diets based on available nutrients, e.g. net energy, true ileal digestible amino acids and available phosphorus. Very little research has been conducted on the trace element needs of the prolific, lean genotype, and therefore most of the published estimates of requirement are probably out of date. In general, requirements have been derived based on the level required to prevent a deficiency symptom and have not been based on maximizing output or taking account of disease challenges e.g. PRRS. The trace mineral needs are generally supplied through the vitamin-trace mineral premix, which uses inorganic mineral salts e.g. sulphates, oxides, chlorides or carbonates. The levels are stated as total, not available, and commercial levels tend to be much higher than the published levels. Minerals perform various biological functions in the body, including maintenance of structural tissue (Calcium, Phosphorus, Manganese); act as enzyme catalysts (Copper, Manganese, Zinc, Iron); assist in oxygen transport (Iron in haemoglobin); regulation of membrane transport and electrolyte balance (Sodium, Potassium, Chloride); prevention of oxidative damage (Selenium, Copper) and are integral components of the hormone and immune systems (Iron, Copper, Zinc, Chromium). There are many interactions between different minerals; notable ones include Iron, Copper and Zinc and also Calcium binding to trace minerals. Many of these interactions occur due to the inorganic trace minerals dissociating after digestion into free ions and being very reactive substances. This process can reduce the bioavailability of the mineral element to the sow. Bioavailability can vary between different sources of the same mineral, the salt form in which it is supplied and even the process used in its extraction or production. Not taking account of the trace mineral content from feed ingredients can sometimes be misleading and cause imbalance between minerals e.g. high iron in phosphate sources. In recent years there has been increasing interest in organic trace minerals, which are formed by a process of chelation between a trace mineral and a hydrolysed protein, small peptides, individual amino acids or even carbohydrates (Figure 1). The strength of the bond linking the metal to the “protein,” will determine how biologically active the mineral will be in the body. If the mineral is highly soluble and weakly bound then it will dissociate into its component parts and act in a similar manner to an inorganic mineral salt. Chelation protects the trace mineral in the metal proteinate from interaction with other minerals and these are then absorbed intact into the blood system by peptide or amino acid uptake pathways rather than the normal metal ion uptake mechanism. The metal is not prone to the physico-chemical factors that can adversely affect efficient uptake of the “unprotected” ions, as found with inorganic sources. The hypothesis is that this will increase net retention, minimize excretion and increase the amount that is biologically available for productive purposes. Possibly the small peptides/amino acids will increase incorporation into the target site aiding the metabolic function e.g. metallo-proteins in enzyme systems. The bioavailability of organic trace minerals can be anywhere between 100-200% better than inorganic minerals.
The sow has a higher demand for trace minerals during the last 3-4 weeks of gestation, throughout lactation and in the first 3-4 weeks after weaning. The daily intake of “available trace mineral” over this time frame will be critical to the level of reproductive performance achieved. The timely delivery of an adequate level of metabolically active trace mineral will ensure that all processes in the body are fully supported to work at full efficiency. It has been demonstrated that a sow at 3rd parity will have less trace mineral content than a sow of similar weight that has not had any litters. Also that the larger the litter size, the lower will be the trace mineral reserve in the sow after weaning. This clearly demonstrates the need to balance input and output and to prevent the sow from being compromised and needing to mobilize her body tissues to satisfy the demand for trace minerals. Increasing the supply of trace minerals to sows during this time period may maintain reproductive performance and improve leg strength, reducing the culling rate and improving sow longevity. New ApproachSows are normally put into the farrowing room 3-7 days before the expected farrowing date. Lactation length varies from 16-21 days. Wean to oestrus interval is anticipated at 5-7 days post –weaning. Confirmation of conception is taken at 25-35 days post-breeding. There is a critical 30-60 day window from time of entry to the farrowing room to completion of breeding and establishment of the next litter, when intake of trace minerals is vital to the successful outcome of the breeding sow. Addition of organic trace minerals to the sow’s daily intake during this time has been shown to improve sow performance (Table 1). In this trial involving 477 sows on three (3) different farms, adding a combination of 50 ppm zinc, 10 ppm manganese and 10 ppm copper as metal proteinates to the base levels of 250 ppm zinc, 90 ppm manganese and 15 ppm copper for the period from weaning to 14 days post-breeding gave a 28% reduction in time from wean to oestrus, a 54% reduction in sows repeat breeding and a reduction of 68% reduction in number of sows culled. The saving of 2.3 days between weaning and breeding each time the sow has a litter e.g. 2.5 farrowings per year, equates to an extra output of 0.3 pigs per sow per year. Another study conducted by the USDA, used 142 parity 1 and 2 animals and fed an additional 5 ppm copper as metal proteinate over and above the basal level of 9 ppm copper continuously from 108 days pre-farrow until the 3rd conception was confirmed. The wean to oestrus interval was reduced from 6.8 days to 6.1 days (P<0.05) and sows bred within 7 days improved from 70% to 87% (P<0.05). Table 1. Sow productivity after feeding organic mineral for 14 days post-weaning (J.Tracy, Chelated Minerals Corporation, unpublished) Parameter Control (ppm) Treatment (Control plus Organics - ppm) Zn 250/ Mn 90/ Cu 15 Zn 50/ Mn 10/ Cu 10 Wean to estrus (days) 8.15 5.89 (P<0.01) Repeat breeding (%) 13.2 6.05 Sows culled (%) 13.2 4.2 Other trials have shown that feeding 200 ppm iron from organic sources to the sow during late gestation and in lactation can enhance the iron status of newborn piglets. This gave benefit in reducing piglet mortality, producing heavier pigs at weaning and shorter wean to breed intervals. This trial indicates that organic iron can gain access across the placental barrier. More recent work has shown that organic selenium in the form of selenium yeast fed in late gestation and through lactation can increase the selenium content of milk and liver reserve in the sow and piglet. It would appear that accumulating data indicates that metal proteinates can be more readily absorbed and incorporated into the target tissue of the sow enhancing reproductive performance and increase sow longevity. RecommendationA separate trace mineral strategy should be developed and used for the lactation diet. The recommended addition of metal proteinate to the normal level of inorganic trace mineral is 40 ppm zinc, 10 ppm copper, 10 ppm manganese and 20 ppm iron. The lactation diet should be fed from day 108 of gestation up to at least 7 days post-weaning and preferably up to the time that conception is confirmed. In time, based on more research that is underway, it may be possible to substitute some of the inorganic minerals in the premix for sows. If it is not possible to feed the lactation diet in the gestation barn after weaning the sow, then a top-dress procedure could be developed to provide a daily dose of 120 mg zinc, 30 mg copper, 30 mg manganese and 60 mg iron per day. It is also recommended that the sodium selenite in the normal premix be replaced with selenium yeast to provide 0.3 ppm. Using the above program in association with chromium picolinate or chromium yeast fed to replacement gilts for at least 6 months before first breeding and continued throughout the whole of the reproductive lifetime of the sow, should elevate the performance of the breeding herd towards 30 pigs per sow per year and improve overall profitability. The sow is treated as an individual and receives a great deal of attention. There are frequent visits to attend to lactation feeding, piglet processing and detection of oestrus and breeding activity. This new approach to boosting sow productivity and improving sow longevity should be easy to implement and monitor and be cost effective on most farms. ARTICLE PUBLISHED IN PIG INTERNATIONAL. February 2003. REPRODUCED BY KIND PERMISSION OF WATT PUBLISHING. Close
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