Arkell, K

Ellis, AD

Harris, P

Thomas, S

English

Nottingham Trent Institutional Repository (IRep)

Adding chopped straw toconcentrate feed: Theeffect of inclusion rate andparticle length on intakebehaviour of horsesAndrea D. Ellis1, Samantha Thomas1, Kate Arkell2and Patricia Harris3Nottingham Trent University, Southwell1, SPILLERS®, Milton Keynes2 andWALTHAM Equine Studies Group, WALTHAM Centre for Pet Nutrition3IntroductionPhysiologically horses have evolved to consume structuralherbage, which takes a considerable amount longer to chewthan cereals or processed feeds.  Previous research has high-lighted a significant reduction in chewing rates for concentra-te feed As the principal stimulus to saliva production in thehorse is mastication, the amount of saliva produced therefo-re can also be compromised when feeding concentrates,which may influence subsequent digestion as well as bufferingwithin the stomach. Dulphy et al. (1997) observed that theintake rates (dry matter per minute = DM/min) almost halvedwhen comparing hay and straw (14 g and 7.9 g DM/min,respectively), highlighting the effect of physico-chemical com-position on chewing efficiency in horses. for buffering sto-mach contents is also compromised. The inclusion of driedchopped forages or chaff has become popular but there arefew published reports on the effects of chaff length or inclu-sion rate on concentrate feed intake behaviour. The purposeof this experiment study was to investigate the effects of incre-asing the amount of straw chaff to concentrate pelletswithin ameal on such behaviour of horses.  Materials and MethodsFeed intake behaviour (chews/minute, intake time/kg WetMatter [WM]) was measured in 6 mature horses (3 large hor-ses: 670±19kg; 3 small horses: 508±12 kg) morning andevening for the following feeds, fed in approximately 1kgmeals: their normal diet mix evening feed (NDM: pellets 50%,Lucerne-straw chaff 15%, and soaked sugarbeet pulp 35%),this feed’s normal diet pellets alone (NDP), a trial pellet (PP),a trial pellet-fibre mix (80% pellets, 10% molasses and 10%short chopped lucerne) core pellet mixed with short choppedlucerne and (PF); PF the trial PF mix with added choppedstraw (at two lengths – short  [S] ~2.5 cm; long [L] ~4 cm)so that the added straw was present in the final mixture atthree inclusion rates (PF10%, 20% and 30% both for L or S). Both morning and evening (7.00 am and 17.00 pm) horseshad not received any other feed for at least 3 hours prior tofeeding times. Horses were offered 1-1.2 kg of each feed andfeed was replaced after approximately 90% of feed had beeneaten. Chews per minute were measured by direct observa-tion technique and removed feed was weighed.  Intake rate(g/minute) and chewing rate (chews/kg) were calculated frommeasurements. Feed volume was measured according to cm3occupied by a set level of each feed using volumetric flasksand a feed particle size index was calculated according tomean particle size of individual ingredients and by allowingfor sieve mesh size used during pelleting procedure.Trial feeds were fed according to a Latin Square design andthe results analysed using analysis of variance after testing fornormal distribution of data. The Spearman rank correlationtest was used to test for associations. A p-value of less than0.05 was taken as the lowest significance level. ResultsMean intake behaviour results are given in Table 1. Multi-variate analysis showed no effect of time of feeding onchews/minute, chews/kg WM or intake rate g/min. Therewas also no effect of horse group (according to size) onchews per minute. There was a significantly increased feedintake time and chews/kg WM for small horses (p<0.01,Figure 1).There was a significant effect of type of feed on intake ratesand chews/kg WM but no effect on chews/minute. IntakeEquine Nutrition Conference Hannover 2005Pferdeheilkunde 21 35Table 1 Mean intake behaviour of six horses (± standard devi-ation).Chews/minb Chews/kg WMcIntake time/kgWM (seconds)cIntake rate(g/minute)cFeeda n Mean s.d. Mean s.d. Mean s.d. Mean s.d.NDM 23 77 ± 12.8 556 ± 174.8 429 ± 108.8 147 ± 36.8NDP 24 65 ± 11.6 472 ± 113.8 435 ±   60.1 140 ± 19.4PP 27 69 ±   9.3 446 ±   99.0 388 ±   76.6 161 ± 32.1PF 28 67 ± 11.3 609 ± 185.7 552 ± 170.2 113 ± 29.8PF10L 24 68 ±   9.2 735 ± 149.8 652 ±   93.7 94 ± 15.7PF10S 24 71 ±   8.6 735 ± 120.1 626 ± 114.6 99 ± 19.4PF20L 24 66 ± 10.0 896 ± 189.8 822 ± 146.8 75 ± 13.1PF20S 24 68 ± 10.0 918 ± 205.4 822 ± 227.4 77 ± 15.6PF30L 22 68 ±   9.1 1074 ± 261.8 950 ± 183.5 64 ± 15.2PF30S 24 69 ± 1103 ± 269.2 954 ± 201.4 66 ± 15.4     a NDM = normal diet mix, NDP = normal diet pellets, PP = trial mix pellets,PF = PP and 10% chopped Lucerne, PF 10,20,30 = refers to % of chopped strawinclusion rate in PF; L = long straw (~4 cm) and S = short straw (~2.5 cm)b measuredc calculated9.7Fig 1 Mean feed intake behaviour for all feed according to hor-ses size (Large or Small) (WM = wet matter; DM = dry matter).Horse size (3 Warmblood/Irish Draught type horses: 670 ±19kg; 3 small TB type horses: 508±12 kg) in this study sho-wed no effect on chews per minute, although previous studiesreport a direct relationship between occlusal surface area andchewing rates (Janis and Ehrhardt 1988, Meyer et al. 1975).The lower intake rates observed in the small horse group weretherefore likely to be due to the smaller oral capacity of tho-se animals (Meyer et al. 1975).  There was no effect on intake behaviour from particle lengthof chaff. It would therefore be recommended to investigatethe effect of increased chaff length on passage rates and onfaecal particle size, as efficiency of feed particle reduction hasbeen directly linked to chewing behaviour in the past (Ellisand Hill 2002, Dulphy et al. 1997, Meyer et al. 1986).ConclusionA clear 120% increase in feed intake time and chews/kg wasobserved as straw chaff was added to a high DM concentra-te feed.  Such an increase, at this level of intake, is likely tolead to a beneficial increase in saliva production withoutadversely affecting passage rate although further work is nee-ded to confirm this.  ReferencesDulphy J. P., Martin-Rosset W., Dubroeucq H., Ballet J. M., Detour A.and Jailler M. (1997): Compared feeding patterns in ad libitumintake of dry forages by horses and sheep. Livestock ProductionScience 52, 49-5636 Pferdeheilkunde 21Feed digestiontimes ranged from 429±108 (NDM) to 954±201 (PF30L)seconds per kg feed as fed (WM). NDM, NDP, and PP wereeaten much more quickly with fewer chews/kg WM than thediets with added straw (p<0.001).  However, there was no significant difference between PF andPF10% (609±185 vs 735±149 chews/kg WM). In addition,there was no significant effect of adding more than 20% addi-tional straw although the number of chews/kg increased (20L896±190 vs 30L 1074±262). There was no significant effect from straw chop length (seeFigure 2). There was a significant correlation between feedvolume and chews/kg WM and between feed particle index andchews/kg WM (Spearman Rank Correlation, p<0.01; see Figu-re 3.a & b).DiscussionResults show an increase in feed intake time and chews/minu-te relative to level of chaff inclusion for treatment feed (PF+).This indicates that adding chaff at an inclusion rate of 20 %to a pellet-fibre mix will lead to significantly longer eatingperiods and increased chews/kg WM (p<0.01). This is alsolikely to lead to an increased saliva production, thus increa-sing the buffering capacity against acid in the stomach. Mey-er et al. (1986) reported that despite similar DM content offeed, hay boluses contain a much greater amount of wet mat-ter (827g/kg WM) than boluses retrieved from horses fed amixed cereal feed (685 g/kg WM) and this effect was direct-ly related to chewing time.  The correlation between feed volume and particle index furt-her confirms these results with one exception. For the normaldiet mix it is likely that the much greater wet matter content dueto inclusion of soaked sugar beet has contributed to a fasterintake rate and formation of bolus, although NDM consistedof a similar level of chaff inclusion and particle size index tothe PF10S mix (see also NDM, Figure 3b). Interestingly due tothe density and weight of sugarbeet NDM does not stand outin Figure 3a, where volume/weight ratio is measured. This isin accordance with previous observations (Ellis and Hill 2002).Therefore the beneficial effect of including chopped forages inconcentrate feed may only be true for high dry matter feed.Further research in this area is necessary. Fig 2 Mean Feed Intake behaviour (for PF10, PF20 and PF30,s.e.) according to straw chop length (Long ~ 4 cm or Short ~2.5cm).Fig 3 Correlation between chews/kg WM and Feed Volume (a)or Feed Particle Index (b) (NDM = normal diet mix).abEllis A. D. and Hill J. (2002): Feed factors affecting intake behaviourand water intake in horses. Proceedings of the 50th EuropeanAssociation of Animal Science, CairoJanis C. M. and Ehrhardt D. (1988): Correlation of relative muzzlewidth and relative insicor width with dietary preference in ungula-tes. Zoological Journal of the Linnean Society, 92, 267-284Meyer H., Ahlswede L. and Reinhardt H. J. (1975): Studies on theduration of feeding, masticatory frequency and mincing of feed inhorses. Deutsche Tierartztliche Wochenschrift, 82, 54-58Equine Nutrition Conference Hannover 2005Pferdeheilkunde 21 37Meyer H., Coenen M. and Gürer C. (1986): Investigations on salivaproduction and chewing effects in horses fed various feeds. Pro-ceedings of the 12th Equine Nutrition and Physiology Society, Gai-nesville, Florida, 92-97A. D. EllisNottingham Trent UniversitySouthwell, NG25 0LZ andrea.ellis@ntu.ac.ukThe effect of the order offeeding oats and choppedalfalfa to horses on therate of feed intake andchewing activityNathalie Brüssow1, Katrin Voigt1, Ingrid Vervuert1, TeresaHollands2, Derek Cuddeford3 and Manfred Coenen1Institute of Animal Nutrition, University of Veterinary Medicine Hannover –Foundation1, Dodson&Horrell, Ringstead2 and Royal (Dick) School of Veteri-nary Studies, Roslin3 UKIntroductionThe speed of intake varies between ~10 min/kg for concen-trates and ~45 min/kg for roughage. Associated with therapid ingestion of concentrates per unit of time is the limitedproduction of saliva (<3kg/kg feed) whilst the consumptionof roughage encourages a profuse production of saliva(~5kg/kg feed, Meyer et al. 1975 1986). Food consumptionaccounts for the major part of the time budget of equids keptunder natural conditions (Frentzen 1994). Concentrate fee-ding reduces the time spent feeding enabling other activitiessuch as work. However, for the majority of horses this ‘free’time is not used in useful activities. The consequent risk is thatabnormal behaviours such as coprophagia or crib biting areperformed and these present areas of concern for animalwelfare (McGreevy et al. 1995; Waters et al. 2002). Anothercritical aspect of using concentrates is that of low saliva pro-duction. Obviously, there is no mechanical problem for thetransport of the rather dry, ensalivated concentrate throughthe oesophagus, but problems may arise in the stomach (Ver-vuert and Coenen 2004) and may influence the function ofthe entire gut (Willard et al. 1977). Differences in saliva pro-duction per unit of feed affect the dry matter concentration ofthe gastric digesta. This interferes with digestive processes inthe stomach, in particular, the acidification of the ingestanecessary to reduce microbial activity and to condition thematerial for digestion in the small intestine. In order to offset the problems associated with the rapid con-sumption of concentrate it is common practice to recommendthat chopped roughage is mixed with the concentrate or, thatroughage be fed before providing the concentrate. However,the precise effects of these recommendations in terms of redu-cing the speed of intake are unknown. The objectives of thepresent study were to elucidate the effects of feeding oats alo-ne before or after feeding chopped alfalfa or, in admixturewith the alfalfa on feed intake and the chewing activity ofhealthy horses.Material and methodsFour horses (560±36 kg M) were used in a changeover expe-riment. The animals were individually kept on wood shavingsin boxes with free access to water. The diets (2 meals/d) con-sisted of chopped alfalfa (0.5 g crude fibre=1.6 g alfalfa/kgM x meal-1) and unprocessed oats (2 g starch=4.5 g oats/kgM x meal-1). The diets were offered alternatively in threeways; a) first alfalfa and immediately thereafter oats (A/O), b)first oats followed by alfalfa (O/A) or c), a mixture of alfalfaand oats (A-O-mix). Each diet was fed for 21 days. The timetaken to consume the feed was recorded for each horse from9 to up to 14 days depending on the type of feed. Parallelspecial halters were used which were equipped with a tube(fixed on the inner side of the strap which passes under thelower jaws), a pressure transducer and a data logger. Any jawmovement produced a signal via an increase in pressure inthe tube (the indirect method). The signals were recorded bya Gemini Data Logger®. Myography measurements were per-formed on two days for each horse per feeding session. Threeelectrodes were mounted superficially, one on the withers, theother two on the rising and the horizontal branch of the man-dibles. The signals were amplified by an electronic amplifier(EMG Signalverstärker, IED®). The software package Dasy-Lab® was used as an interface for recording and reading ofdata. The data were analysed using an analysis of variance(Statistica®) and the results are presented as mean ± stan-dard deviation (SD). ResultsThe quickest intake was recorded with the alfalfa-oats mixtu-re. The rate of intake of both oats and alfalfa was not influen-ced by the feeding order (Table 1). The chewing activity(chews/100 g) was similar for the A-O-Mix and oats at about

Adding chopped straw to concentrate feed: the effect of inclusion rate and particle length on intake behaviour of horses

Abstract

Similar works

Full text

Available Versions

Nottingham Trent Institutional Repository (IRep)