No abstract

The objective of this experiment was to quantify ruminal digestive processes that could help to identify factors limiting DMI when silages differing in grass maturity were fed to dairy cows. Four silages were harvested at 1-wk intervals from a primary growth of a timothy-meadow fescue sward, resulting in feeds with digestible OM content in DM (D-value) of 739, 730, 707, and 639 g/kg in the order of succeeding harvest date. Four ruminally cannulated dairy cows were given ad libitum access to these silages supplemented with 7 kg concentrate per day in a 4 x 4 Latin square design. Rumen function was clearly affected by decreasing digestibility of silage fed. Passage rate of digestible NDF (DNDF) and indigestible NDF (INDF) increased, but it could not prevent the accumulation of DM, NDF, DNDF, and INDF into the rumen when silages of progressing grass maturity were fed. The greatest proportional increases in rumen pool were found in INDF and in medium particles (separated by wet sieving and measuring 315 to 2,500 microm). The passage of medium INDF particles decreased (P < 0.01) linearly (from 0.0365/h to 0.0281/h) with increasing maturity of grass ensiled, and it was slower than passage of small (80 to 315 microm) particles (on average 0.0524/h). Particle size reduction of large INDF particles to medium INDF particles was slower (P < 0.001) in the early cut silages (0.0216/h to 0.0484/h) but reduction of medium INDF particles to small INDF particles was faster (P < 0.001) in early cut silages (0.0436 to 0.0305). Passage of medium size particles and(or) rate of medium particle breakdown to small particles were potential intake-constraining properties of low digestibility forages, whereas large particle reduction to medium particles seemed not to be limiting. The increased feed intake of the early-cut silages was accompanied by decreased rumen fill, suggesting that rumen fill was not at least solely responsible for feed intake control.

No abstract

Based on potential health benefits, there is a need to develop effective strategies for enhancing milk fat concentrations of cis-9 18:1, 18:3 n-3 and conjugated linoleic (CLA) content in milk without compromising the sensory or storage characteristics of processed milk or dairy products. Sixteen Finnish Ayrshire dairy cows were used in a cyclic change-over experiment with four 21-d experimental periods and a 4 x 2 x 2 factorial arrangement of treatments to evaluate the effects of forage conservation method, concentrate level and supplements of propylene glycol (PG), and their interactions on milk fatty acid composition and vitamin content. Experimental treatments consisted of four conserved forages offered ad libitum, supplemented with two levels of a standard concentrate (7 or 10 kg/d) and PG (0 and 210 g/d) fed as three equal meals. Primary growths of timothy and meadow fescue sward were conserved by ensiling with none (NA), an inoculant enzyme preparation (IE) or a formic acid based (FORM) additive or as hay 1 week later. Conservation of grass by drying rather than ensiling resulted in lower forage 18:2n-6, 18:3n-3, total fatty acid and fat-soluble vitamin concentrations. In spite of lower intakes, milk fat 18:2n-6 and 18:3n-3 content was higher (P < 0.05) for hay than for silage diets (12.1, 9.6, 9.6 and 9.3 and 5.00, 3.51, 4.27 and 2.93 g/kg total fatty acids, for hay, NA, IE and FORM silages, respectively). Forage conservation method had no clear effects on milk trans 18:1 or CLA content. Compared with silage, hay diets resulted in milk containing lower (P < 0.001) riboflavin, alpha-tocopherol and beta-carotene concentrations, but had no effect on ascorbic acid, thiamine, pyridoxine or retinol content. Feeding more concentrates had no effect on milk fatty acid composition or milk vitamin content, other than lowering (P < 0.001) 16:0 concentrations from 348 to 338 g/kg fatty acids. Supplements of PG led to small (P < 0.05) increases in milk 13:0 anteiso and 15:0 content from 1.06 and 11.3 to 1.22 and 12.6 g/kg fatty acids and reduced (P < 0.05) the concentrations of ascorbic acid (16.1 v. 15.1 g/kg milk).

No abstract

Four silages were prepared at 1-week intervals from a primary growth of timothy-meadow fescue sward. They were offered to 32 Finnish Ayrshire cows and supplemented with 7 or 10 kg of concentrate containing 0 or 1·15 kg rapeseed meal (RSM). The basal concentrate consisted of barley, oats and molassed sugar-beet pulp (2: 2: 1) and minerals. Diets were arranged 4 × 2 × 2 factorially in a cyclic change-over experiment with four periods of 21 days each.Silages contained 739, 730, 707 and 639 g digestible organic matter (D value) per kg dry matter (DM) for harvests I, II, III and IV, respectively. All dietary factors had marked effects on the performance of the cows but generally interactions between treatments could not be detected. A decrease of 10 g/kg in silage D value decreased energy-corrected milk (ECM) production of the cows by 0·50 kg/day and silage DM intake by 0·162 kg/day. An increment of 1 kg concentrate DM decreased silage DM intake by 0·61 kg and yielded 0·55 kg more ECM per day. Inclusion of RSM into the concentrate increased daily ECM production by 1·7 kg and silage DM intake by 0·60 kg/kg RSM when substituting the basal concentrate. Milk yield and yields of milk constituents decreased curvilinearly with delayed date of harvest the difference being greatest between the last two cuts and thus closely reflected the changes in silage D value. Milk protein concentration increased as apparent digestibility (P < 0.001) and concentrate level in the diet increased (P < 0.001). Milk fat concentration was not affected by the dietary treatments.Marginal ECM production responses to estimated metabolizable energy (ME) intake were higher when intake was manipulated with the date of silage harvest (0·138 kg ECM per MJ additional ME) compared with increased concentrate feeding (0·103); highest response was achieved by RSM feeding (0·244). Additional intake of calculated amino acids absorbed from the small intestine (AAT) manipulated by silage harvest time resulted in the highest marginal response (0·59 g milk protein per g additional AAT), while increased concentrate feeding and inclusion of RSM were equal (0·50 v. 0·49, respectively). Improving silage quality by earlier harvest resulted in higher milk yield, and in greater efficiency in the use of increments of estimated ME and AAT than was seen with increased concentrate feeding. Protein supplementation improved milk production irrespective of silage harvest date.

Aim:  Lactic acid bacteria (LAB) strains shown to have broad‐spectrum antimicrobial activity were screened for potential as grass silage inoculants. The strains capable of rapidly lowering the pH of the grass matrix and with low proteolytic activity were assessed in laboratory‐scale silos in a grass matrix containing natural microbial flora. Methods and Results:  Screening of nine candidate strains was performed first in a grass extract medium. The four most promising strains were selected on the basis of growth rate in the medium, capacity to reduce pH and ability to limit the formation of ammonia‐N. The efficiency of the selected strains was further assessed in a laboratory‐scale ensiling experiment. Untreated (no additive) and formic acid served as controls. All tested inoculants improved silage quality compared with untreated. With one exception (Pediococcus parvulus E315) the fermentation losses in the inoculated silages were even lower than in the acid‐treated control silage. Pure lactic acid fermentation was obtained in the timothy‐meadow fescue silage with all inoculants. The results obtained in the ensiling experiments were consistent with those of the screening procedure, which appeared to predict correctly the potential of LAB as silage inoculants. The strains with a low ammonia production rate in the grass extract medium behaved similarly in the silage. Especially in this respect the strain Lactobacillus plantarum E76 was superior to the other candidates. Conclusions:  The screening method using grass extract proved to be useful in strain selection. Significance and Impact of the Study:  The rapid screening method developed for the LAB strains provides a useful tool for more systematic product development of commercial inoculant preparations. Time consuming and laborious ensiling experiments can be limited only to the most promising strains.

The objective of this study was to evaluate the production and physiological responses of dairy cows to the substitution of fava bean for rapeseed meal at 2 protein supplementation levels in grass silage-based diets. We used 6 primiparous and 6 multiparous Finnish Ayrshire cows in a cyclic changeover trial with a 2×3 factorial arrangement of treatments. The experimental diets consisted of formic acid-treated timothy-meadow fescue silage and 3 isonitrogenous concentrates containing either rapeseed meal, fava bean, or a 1:1 mixture of rapeseed meal and fava bean at low and high inclusion rates, resulting in concentrate crude protein (CP) levels of 15.4 and 19.0% in dry matter. Silage dry matter intake decreased linearly when rapeseed meal was replaced with fava bean, the negative effect being more distinct at the high CP level than the low (-2.3 vs. -0.9kg/d, respectively). Similarly, milk and milk protein yields decreased linearly with fava bean, the change tending to be greater at the high CP level than the low. Yield of milk fat was lower for fava bean compared with rapeseed meal, the difference showing no interaction with CP level. Especially at the high CP level, milk urea concentration was higher with fava bean compared with rapeseed meal indicating better utilization of protein from the rapeseed meal. The apparent total-tract organic matter digestibility did not differ between treatments at the low CP level, but digestibility was higher for fava bean than for rapeseed meal at the high CP level. Plasma concentrations of essential amino acids, including methionine and lysine, were lower for fava bean than for rapeseed meal. Compared with rapeseed meal, the use of fava bean in dairy cow diets as the sole protein supplement decreased silage intake and milk production in highly digestible formic acid-treated grass silage-based diets.