ESTIMATION OF HAY ENERGY VALUE WITH A REGRESSION EQUATION

Jasna M. A. STEKAR^a), F. ZAGOŽEN, A. GOLOB
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: English

ABSTRACT
825 random samples of hay, 655 the first cut and 170 aftergrass, were analysed according to Weende analysis. The results were accounted with the statistical package SPSS so that multiple regessions were calculated for the starch equivalent (SE) and net energy for lactation (NEL) for all samples and separately for the first cut and aftergrass respect. The equations were carried out with the stepwise inculding the separate nutrients. All multiple regression coefficients (R) were very higly significant. For the first cut samples, the estimation of SE on the base of all nutrients was very accurate (R=0.9796, s.e.=1.4502). For the practice, it is sufficient to estimate it with the crude fibre (CF) and crude protein (CP) contents only (R=0.9613, s.e.=1.9861). In the case of estimation of NEL it is necessary to take into account all nutrients (R=0.9429, s.e.=0.1822). It is possible to estimate SE well with all nutrients (R=0.95488, s.e.=0.14164) in afftergrass. For NEL CP, ether extract and nitrogen-free extractives (R=0.93487, s.e.=0.14164) are sufficient. When the samples are not defined, SE and NEL should be estimated with all nutrients (R=0.97186, s.e.=1.69134 resp. R=0.95646, s.e.=0.15974).

CHEMICAL COMPOSITION AND NUTRITIVE VALUE OF GRASS, CONSERVED BY VARIOUS METHODS

J. ŽGAJNAR^a), A. LAVRENČIČ, J. STOPAR
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: English

ABSTRACT
Chemical composition, apparent digestibility, degradability of dry matter and crude protein in the rumen at 1.5, 3, 6, 12, 24 and 48 hours after incubation, and the effective degradability of crude protein and nutritive value were established in deep frozen grass and in silages, made from unwilted grass, unwilted grass conserved with 0.4 % EnsimaxÒ , and wilted grass. When fresh unwilted grass (201 g per kg DM) was ensiled very carefully in 1 m³ silos, no significant differences in chemical composition, degradability, apparent digestibility and nutritive value were observed in comparison to silage conserved with EnsimaxÒ . Silage from wilted grass was significantly less digestible and had 17 % less digestible crude protein (DCP), starch equivalent (SE) and NEL (MJ) per kg DM compared to silage from unwilted grass.

THE EFFECT OF THE SILAGE ADDITIVE PLANTANAZE^® ON THE CHEMICAL COMPOSITION AND IN VITRO DIGESTIBILITY OF DIRECT CUT GRASS SILAGE

D. BABNIK^a), Jasna M.A. STEKAR, Jože VERBIČ, Alenka MALENŠEK
^a) Kmetijski inštitut Slovenije, Hacquetova 17, SI-1000 Ljubljana, Slovenia

Original scientific paper
Language: Slovene

ABSTRACT
The effect of the silage additive Plantanaze^®, which contained lactic acid bacteria (L. plantarum, P. pentosaceus) and cellulolytic enzymes, on the chemical composition and the in vitro digestibility of direct cut grass silage was tested in laboratory silos. The silos were opened after 271 days. The silage with the addition of Plantanaze^® contained in comparison with the control silage more sugars (32 vs. 11 g kg^-1 DM, P< 0.05) and less crude fibre (284 vs. 295 g kg^-1 DM, P< 0.05), cellulose (312 vs. 318 g kg^-1 DM, P< 0.05) and ADF (352 vs. 358 g kg^-1 DM, P< 0.05). The concentrations of crude protein, ash, ADL, NDF and hemicelluloses were not significantly different. The in vitro digestibility of OM according to Tilley and Terry (1963) was not-significantly higher (65.6%) in the silage with Plantanaze^® than in the control (64.7%). Non-significantly higher was also the OM digestibility which was estimated on the basis of chemical composition and the amount of gas produced during the in vitro incubation of samples with rumen liquor (63.0% vs. 62.2%). Because of lower mass losses (4.45 vs. 6.97 kg t^-1 ensiled forage, P< 0.001) and somewhat higher concentration of NEL (5.01 vs. 4.93 MJ kg^-1 DM) the loss of NEL in the silage with the addition of Plantanaze^® was lower (3.8 MJ NEL t^-1 ensiled forage) than in the silage without silage additive (62.0 MJ NEL t^-1 ensiled forage).

THE EFFECT OF SEASON ON THE CONCENT OF UREA IN MILK OF COWS

Marija RAJČEVIČ^a), I. JAZBEC, Marija SIRK, J. LEVSTEK
^a) Poslovni sistem Mercator, d.d., Dunajska 107, SI-1000 Ljubljana, Slovenia

Original scientific paper
Language: Slovene

ABSTRACT
Cows of Friesian breed from the farms A and B were taken into research in the years 1992 - 1994 to determine the urea (and protein) in milk and to establish the deficient or sufficient supply with protein. Winter and summer periods were studied separately. On the both farms the content of urea in milk increased in summer, on the farm A it was on average (n=60) 5.24 ± 0.57 mmol/l and on the farm B (n=68) 7.82 ± 0.804 mmol/l. In the winter the urea in milk was on average (n=60) 3.57 ± 0.534 mmol/l on the farm A and 5.01 ± 0.745 mmol/l (n=100) on the farm B. On the both farms the difference in the average concentration of urea between the winter and summer was statistically highly significant (p=0.001) and is due to nutrition regime or to unbalance of rations with energy and protein.

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