492


EQUINE VETERINARY EDUCATION / AE / SEPTEMBER 2018


TABLE 3: Quantity of concentrate feed per meal, which equates to an intake of 1 or 2 g/kg bwt of total starch and water soluble sugar (NSC) for a 500 kg horse


Amount that could be fed and not exceed suggested thresholds (excluding chaff)


Feed (starch and WSC content as fed) 10%


25% 35% 40%


Feed example Low starch feed


Competition feed


Traditional racing feed Barley


2 g/kg bwt (approx) 10 kg


4 kg


2.9 kg 2.5 kg


1 g/kg bwt (approx.) 5 kg


2 kg 1.4 kg 1.25 kg


and cereal byproducts. Due to the widespread use of cereal byproducts in so-called ‘low energy’ feeds these feeds cannot automatically be regarded as being synonymous with ‘low starch’ or low NSC. Starch/sugar content is not unfortunately a required statutory declaration on packaging globally and therefore a direct approach to the feed manufacturer may be required to establish the NSC content of the feed if it is not offered on ancillary information such as literature or a website. Ideally, evidence that the feed produces an appropriate insulin response in any target animal group should also be available.


Effect of soaking forage on WSC Although soaking, especially at temperatures of around 16°C or higher, may significantly reduce the WSC content of a hay (Longland et al. 2014), the extent of the reduction can be variable and nonpredictable (Longland et al. 2011b) and therefore this should only be an adjunct technique to choosing a low NSC hay if required medically. If it is necessary that a low NSC intake is achieved from the forage, the authors advise that the NSC content should be measured post-soaking. It is also important to note that soaking hay results in a small loss of dry matter which may not be important in ad libitum fed animals but can be key under weight loss scenarios (Longland et al. 2011a,b; Martinson et al. 2012; Argo et al. 2015). Soaking also results in loss of some water soluble protein and other nutrients meaning that a forage balancer will be required in most cases to balance the diet.


Hygienic quality


Feed hygiene covers all the measures that are necessary to minimise health risks due to physical, chemical or biological contamination of feeds and feedstuffs (e.g. as described in the EC Regulation on Feed Hygiene No 183/2005) and this also applies to forages. The hygienic (Wichert et al. 2008; Kamphues 2013) and nutritional quality of forage (Table 2), as well as the quantity fed and the suitability of its nutritional make-up, typically should be the first area for investigation during any nutritional evaluation and in particular where there is a generalised failure to perform or thrive and during investigations of digestive disturbances (including recurrent colic, gastric ulcers, or presence of abnormal droppings). This information is also essential where recurrent airway obstruction is suspected or weight loss is desired. In any hygienic investigation, whilst the look, smell and feel are obviously important, a macroscopic evaluation should be


© 2016 EVJ Ltd


routine to look for obvious moulds and the presence of contaminants such as sand/soil, weeds and various poisonous plants (Kamphues 2013). In addition, due to the importance of water in micro-organism growth, a follow-up DM determination can be very helpful. A guide to the types and acceptable levels of bacteria, moulds and yeasts in different types of forages have been previously determined (Kamphues 2013). Hay imported from warm climates can often provide a low mould option, as can well made haylage. Hay from Northern Europe can, however, be more problematic and it can be difficult to achieve a consistently clean supply. An effective reduction in total viable count and reduction in respirable particles has been reported when hay is steamed appropriately (James and Moore-Colyer 2010), whereas prolonged soaking of hay significantly increases the mould and bacterial counts (Moore-Colyer et al. 2014). Recently, there has been more interest in the potential


impact of mycotoxins on equine health, from forage or indeed other feedstuffs. Mycotoxins can be a systemic issue, affecting for example immunity, digestive health, reproduction and overall performance (Riet-Correa et al. 2013), although little data is available to give guidance on the lower critical level of mycotoxin contamination significant for health and performance in horses. In addition, the significance of a raised mycotoxin result in hay or feed can be difficult to interpret as the impact will depend on the relative intake of the contaminated material. There are, however, recommended acceptable upper


levels of contamination and depending on the country, legal limits for certain mycotoxins (e.g. https://www.food.gov.uk/ business-industry/farmingfood/crops/mycotoxinsguidance/ animalfeed). Identification of mycotoxin contamination of forage or feed is also problematic, due to the difficulty in achieving representative samples and can be described as ‘looking for a needle’ in the proverbial haystack. However, there is now comprehensive mycotoxin screening available that canidentify over35mycotoxinswithinasingle screen (Abdel-Wahhab and Kholif 2008). Mycotoxins are very chemically robust and thermally resistant and so difficult to eliminate where suspected or identified. Steaming of hay may not destroymycotoxins, although washing of grains has been shown to reduce the contamination (Trenholm et al. 1992). Feed additives or mycotoxin binders may offer some protection whilst they remain in the digestive tract (Raymond et al. 2003) and these are sometimes included in proprietary feeds or supplements, although this will depend on the legislation present in the country where they are being fed. Mycotoxin binders would, however, need to be fed several times a day to retain efficacy and


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84