Abstract
This study investigated the influence of different loading levels, cutting and mixing times on total mixed ration (TMR) homogeneity delivered along the feeding alley of dairy cows. The TMR homogeneity along the alley was investigated according to three mixing wagon loads (40, 70 and 100% of the nominal capacity), three cutting times (4, 5 and 6 min) and three mixing times (4, 5 and 6 min). The diet (70:30 forage/concentrate ratio) was supplied by a two-screws vertical mixing wagon (maximum nominal capacity, 21 m3). A preliminary variance analysis of chemical parameters was performed on samples collected in the mixing wagon: samples of released TMR were taken at the beginning, in the middle and at the end of the feeding alley (50 m long). The chemical parameters of the diet revealed no significant effects on the homogeneity of the samples for cutting time (p>.05). Mixing wagon loading affected crude protein (CP) (p < .05) and neutral detergent fibre (NDF) content (p < .01), while mixing time influenced dry matter (DM) of the diet (p < .05). The loading level of the mixing wagon affected the difference of the collected samples from the formulated diet for ash content. The 70% of the nominal capacity load of the mixing wagon showed the lower difference values between expected and chemically determined NDF (p < .01), CP (p < .05) and ether extract (EE) (p < .05) content in the diet. The DM and NDF differences along the alley, affected by mixing times (p < .05), showed a poor uniformity of ingredients during distribution, although samples uniformity at wagon level.HighlightsThe efficiency of a two-screw vertical mixing wagon on total mixed ratio uniformity was evaluated on diet samples delivered along the feeding alley.Three loading levels, three cutting and three mixing times were considered for the mixing wagon.Mixing wagon loading affected CP and NDF content; mixing time influenced DM and NDF content at the delivery points.
Highlights
The total mixed ration (TMR) system for dairy cows nutrition was introduced to provide a consistent supply of nutrients to rumen microbes, to optimise rumen function and improve the efficiency of nutrient utilisation, in some circumstances it may not accurately reflect the formulated diet, slightly varying day by day (Sova et al 2014)
TMR homogeneity and feed particle size distribution are of primary importance in dairy cow nutrition, but these elements are often subdued to the efficiency of the mixing wagon that can be limited by the loading level and cutting and mixing times among others factors (Buckmaster 2009a, 2009b)
The following items i) loading level of the mixing wagon (100, 70 and 40% of maximum nominal capacity); ii) cutting time of roughage (4, 5 or 6 min.) and iii) mixing time of TMR (4, 5 or 6 min) were considered independent variables in the model, affecting TMR uniformity, or dry matter (DM), crude protein (CP), ether extract (EE), neutral detergent fibre (NDF) and ashes values differences of the samples collected at the feeding trough (5 samples at the beginning 0 m; 5 samples in middle 25 m; 5 samples at the end, 50 m) from respective chemical parameters of the formulated diet collected in the wagon
Summary
The total mixed ration (TMR) system for dairy cows nutrition was introduced to provide a consistent supply of nutrients to rumen microbes, to optimise rumen function and improve the efficiency of nutrient utilisation, in some circumstances it may not accurately reflect the formulated diet, slightly varying day by day (Sova et al 2014). Together with the balance between the components of the diet to allow suitable rumen condition, the feed particle size distribution and the physical effectiveness of the diet lead to adequate rumination stimuli and intensity of rumen fermentation (Zebeli et al 2011). In this view, TMR homogeneity and feed particle size distribution are of primary importance in dairy cow nutrition, but these elements are often subdued to the efficiency of the mixing wagon that can be limited by the loading level and cutting and mixing times among others factors (Buckmaster 2009a, 2009b). For the above described reasons, the aim of this trial was to determine the influence of different combinations of loading levels, cutting and mixing times on homogeneity of dairy cows TMR along the feeding alley
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