The aim of the review is to present mechanisms of digestion in horses through a functional description of the digestive system’s structure with emphasis on nutrient digestibility. In the era of an increasingly intensive and specialised sport usage of horses, also the significance of balancing their dietary nutrient value in accordance with individual requirements of these animals is gaining in importance. At the same time, it is not possible to meet nutritional requirements of a sport horse without knowledge about feed utilisation. In many farm animal species, digestibility is measured postmortem or via complicated and expensive cannulation of the digestive system. In horses, these methods are not applied due to ethical approaches or other limitations (e.g. sport horses); therefore, the importance of marker-based techniques is growing, although not much data is published in the available literature (Sales, 2012). Moreover, in contrast to other non-ruminants, horses are naturally adapted to a constant intake of large quantities of roughages. However, during intensive sport training, they are primarily fed concentrated diets with high amounts of easily digestible, non-structural carbohydrates and reduced amounts of dietary fibre fractions. Therefore, the risk of metabolic diseases and behavioural disorders in the horse increases.
The aim of the study was to investigate experimentally the effects of restricted or ad libitum feeding in the far-off period on performance of dairy cows. Two groups of Polish Holstein-Friesian cows having 19 animals in each group were allotted to two planes of nutrition in the far-off period from -56 to -22 days. The ADLIB group was fed ad libitum (DMI 12.9 kg) while in the RES group the dry matter intake was restricted by 3 kg DM compared to the average dry matter during the last 7 days in the ADLIB group. Average daily energy intake decreased from 8.90 UFL in the ADLIB to 6.83 UFL in the RES group. In the close-up period and after parturition, the cows of both groups were given the same diet. In restrictively fed cows, there was a tendency to a greater decrease in BCS during both the dry period (P=0.09) and lactation (P=0.07). After parturition milk production, fertility indices and blood concentration of IGF-1, insulin and glucose were not significantly affected by the far-off treatment. In the RES group, lower BHBA 3 days before calving and on day 5 of lactation and lower NEFA on day 28 of lactation were recorded. Also in this group higher levels of glucose 3 days before calving, triiodothyronine (T3) on days -30 and 5, and thyroxine (T4) on days -3 and 28 were observed. It is concluded that restricted feeding in the far-off period positively affected blood indicators of lipomobilization during the transition period, but had little effect on performance of lactating cows. In spite of low energy, high-fibre diet offered ad libitum in the faroff period resulted in the energy overfeeding compared to the INRA system recommendation.
The aim of the study was to investigate the effect of BCS (Body Condition Score) on the calving day and its decrease during early lactation on the biochemical blood indices and reproductive performance. One hundred and thirty-one Polish Holstein-Friesian cows were divided into three groups according to the North-American body condition score on the calving day (AC≤3.5 point BCS; MID 3.51-3.75 point BCS; FAT>3.75 point BCS) and according to the decrease in BCS during early lactation (HG >0.49 point BCS; WEL 0.49-0.25 point BCS, L<0.25 point BCS). In current study, significant interaction between change of BCS during early lactation and time of blood sampling on BHBA concentration was observed. In the AC group (≤3.5 BCS), the highest concentrations of glucose on 3 and 5 d of lactation compared to the MID and FAT groups and of insulin on 28 d and also IGF-I on 5 and 28 d of lactation compared to the FAT group were recorded. In the FAT group, the highest concentration of NEFA on 3 and 5 d compared to the AC group and of BHBA on 28 d of lactation compared to the MID group was recorded. The body condition score on the parturition day affected the reproductive performance; in the FAT group (>3.75 BCS) the lowest conception rate of the first insemination, insemination index and thereby the longest days open were observed. The highest decreases in BCS (HG >0.49 points) resulted in increased concentrations of NEFA on 3 d and of BHBA on 3 and 5 d. Moreover, in the HG group, the lowest concentration of T3 on 3, 5 and 28 d as compared to the WEL group was recorded. We concluded that the BCS (>3.5 points) on the calving day had a significantly negative effect on the metabolic status of dairy cows in the postpartum period estimated by the concentration of biochemical blood indices characterising carbohydrates (IGF-I, insulin) and lipid (NEFA, BHBA) metabolism and also the reproductive performance such as the conception rate of the first insemination, insemination index, days open. We suggested that the blood serum concentrations of IGF-I and NEFA were the most sensitive biochemical markers of the metabolic status of dairy cows in our study.