Long-stemmed vs. cut haylage in bales--Effects on fermentation, aerobic storage stability, equine eating behaviour and characteristics of equine faeces

Wrapped forages used in equine nutrition are often conserved long-stemmed, although cutting or chopping the herbage prior to ensiling has been shown to produce a larger and/or faster production of lactic acid and a prolonged aerobic storage stability in other ensiling systems. An experiment comparing conservation and feeding of cut and long-stemmed grass haylage in bales was therefore completed. Bale characteristics, chemical and microbial composition of the conserved haylage and aerobic storage stability of opened bales were compared between cut and long-stemmed haylage, as well as effects of the two forage treatments on equine eating behaviour and faecal characteristics. The experimental design of the feeding experiment was a cross-over with 10 horses divided into two groups in two periods, with each period being four weeks. Bale weight, dry matter loss during fermentation, chemical composition and aerobic storage stability was similar between cut and long-stemmed haylage. Dry matter losses during fermentation were less than 10g/kg in both forage treatments. Microbial composition differed only in counts of enterobacteria, which were slightly higher (P=0.004) in the cut haylage compared to the long-stemmed haylage. The aerobic storage stability test lasted for five days during which both forage treatments were stable. Ethanol content decreased in both cut and long-stemmed haylage with increasing number of days of aerobic storage. When horses were fed cut haylage, faecal pH was slightly higher and faecal content of acetic acid were slightly lower than when horses were fed long-stemmed haylage, but differences were small and not considered to be biologically important. Faecal particle size distribution was similar when horses were fed cut or long-stemmed haylage. Eating time (min/kgDM) was similar, chewing rate (chews/min) was slightly higher (P=0.01) and number of chews/kgDM was lower (P<0.0001) when horses were fed cut haylage compared to long-stemmed. Differences were very small (84 vs. 82chews/min for cut and long-stemmed haylage respectively), but the implications of this difference over 24h or longer periods is not known. Individual variation among horses was larger than differences due to cut or long-stemmed forage in both eating behaviour and faecal characteristics.