Cultivating alfalfa mixed with timothy: Changes in harvest and nutritive value.
The cultivation area of alfalfa has expanded in Estonia. The hybrid alfalfa breeded in Jõgeva (Medicago varia Mart.) and the imported alfalfa (Medicago sativa L.) are being cultivated in unmixed sowings as well as in the mixed sowings with grasses. The complex experiment aimed at the determination of the optimum proportion of timothy in the alfalfa mixture and the investigation of changes of the nutritive value was carried out in the Juuliku Experimental Farm on the soddy-calcarous sandy clay soil from 1999–2000.
The timothy was added to the unmixed sowings of the alfalfa varieties from Estonia and United States in the quantities of 0, 2, 4 or 6 kg ha-1 (according to the experimental variation) in order to achieve the proportion of timothy of 20–40% in the harvest.
The weather conditions did not favour the growth of alfalfa in 2000. The cool, dry period with the night frosts lasted until the middle of May. The September was also dry and with the night frosts. Thus the first and the third harvests of the three-mowing utilisation were grown under droughty and cool weather conditions.
The zootechnical analysis (Weende scheme) was carried out; the digestibility of organic matter was determined in sacco; the content of Metabolizable Energy (ME) and the Protein Balance Value (PBV) were calculated on the basis of the measured parameters.
The results indicated that the addition of timothy 2 kg ha-1 resulted in the 80% share of alfalfa in the harvest of the first mowing in case of all used alfalfa varieties. The timothy addition 4 kg ha-1 led to the 70% content of Estonian varieties and 75% content of American varieties in the harvest respectively. The addition of 6 kg ha-1 this figure was <60% for Estonian varieties and 70% for American varieties. The effect of timothy sowing ratio on the botanical composition was smaller in the harvest of the second and third mowing.
The addition of timothy to the seed mixture increased the yield of dry matter by 37% in case of Estonian varieties (timothy 4 kg ha-1) and by 36% for American varieties (timothy 2 kg ha-1). The third harvest of American varieties constituted 20% of total harvest, the Estonian varieties practically lacked the third harvest.
The analysis of the chemical composition showed no credible difference between the alfalfa varieties. The increase of the sowing ratio of the timothy reduced the protein and Ca content while not affecting the crude fibre, P and K content.
The variation of the sowing ratio of timothy did not influence the dry matter ME content. The varieties Karlu and WL 252 HQ had the first harvest with the higher nutritive value and the variety WL 324 had the lower nutritive value respectively.
In order to estimate of the protein value was calculated the PBV. It was positive. The increase of the timothy sowing ratio decreased the PBV and it approached nil in case of 25–30% proportion of timothy in the harvest of the first mowing. The PBV of the harvest of the third mowing was 2–3 times that of previous mowings and the effect of timothy sowing ratio was absent.