RESUMEN

Effect on nylon-bag digestibility of rolling and steam-flaking as such or followed by grinding through a 1-mm screen was studied in wheat, barley and maize grains. Digestibilities of ground grains were not different, irrespective of rolling or steam-flaking, except flaked and ground barley, which was less digestible than ground barley. Rolled and flaked grains were less digestible than ground grains, except for rolled wheat which was not different from ground wheat. These results suggest that particle size due to grinding is more important than other methods of processing. Dry matter and protein degradabilities of steam-flaked grains were investigated by in sacco technique and compared with unprocessed grains. Dry matter degradability during incubation periods up to 24 h was reduced for steam-flaked wheat and barley, but increased for flaked maize. Protein degradability was lower for flaked grains.

Asunto(s)

RESUMEN

Three experiments were conducted to investigate the effect of virginiamycin. Digestibility was determined with wethers, fed a diet of 0.65 maize silage and 0.35 concentrate on a dry matter basis (Experiment I) or a complete dry feed (Experiment II) at maintenance, and with growing bulls fed a maize silage diet ad libitum supplemented with 7.5 g concentrate per kg live weight (Experiment III). Virginiamycin was incorporated at 0 or 65 ppm in the concentrate and 0 or 25 ppm in the complete dry feed. No significant effect on dry or organic matter digestibility was observed, although digestibilities of protein and ether extract were reduced by virginiamycin in experiments I and II, respectively. Rumen fermentation was studied in experiments I and II. Virginiamycin increased acetic acid concentration and reduced butyric acid concentration in experiment I, but exerted no significant effect in experiment II. An interaction between diet type and virginiamycin was found for the C2/C3 ratio. Nitrogen balance, measured in experiment III, was not affected by virginiamycin.

Asunto(s)

RESUMEN

Two experiments have been conducted to study the effect of virginiamycin in a maize silage diet (I) or a complete dry feed (II). Virginiamycin was incorporated at 0 or 65 mg per kg concentrate which was fed at 0.75% of the live weight of 43 Belgian white-red bulls (I), or at 0 or 25 mg per kg complete dry feed for 24 Belgian white-blue bulls (II). In the first experiment daily gain was increased by virginiamycin from 1.28 to 1.38 kg without effect on intake, but with an improved feed conversion from 5.99 to 5.60 kg dry matter/kg gain. In the second experiment daily gain, daily dry matter intake and feed conversion were not influenced by virginiamycin. The differences between experiments may suggest that the response to virginiamycin probably depends on the diet type, although no significant interaction was found between diet type and virginiamycin with regard to growth rate (P greater than 0.10). In both experiments, fasting weight loss, dressing percent and carcass classification and composition were not affected by virginiamycin.

Asunto(s)

RESUMEN

Three rumen-fistulated cows fed maize silage and concentrates were supplemented with either soybean oil meal or urea, associated or not with isoacids. The isoacids increased the volatile fatty acid concentration, lowered the ruminal ammonia concentration and in sacco dry matter disappearance and did not influence blood parameters.

Asunto(s)

RESUMEN

117 white-red beef bulls were involved to investigate the effect of lasalocid-sodium when fed either during the grazing period, or the finishing period, or during both subsequent periods. The ionophore was fed at 250 mg daily per head incorporated in 1 kg dry sugar beet pulp on pasture and at 65 mg per kg concentrate afterwards (corresponding with 27 ppm in the ration DM). The finishing diet consisted of maize silage ad libitum and 0.75 kg concentrate per 100 kg liveweight per day. On pasture lasalocid significantly increased daily gain form 0.6 to more than 0.7 kg, without affecting the grazed area per animal. During the finishing period growth rate was only slightly affected by lasalocid, but feed intake was reduced (P less than 0.05) and feed conversion improved (P less than 0.05). Feeding lasalocid permanently for more than 400 days did not reduce these positive effects. Cumulative daily gain, total feed intake per head and feed conversion were 1.12 kg, 2176 kg dry matter (DM) and 4.70 kg DM. These figures amounted to 1.05 kg, 2283 kg DM and 5.16 kg DM when no lasalocid was fed; 1.06 kg, 2141 kg DM and 4.87 kg DM when lasalocid was only fed during the finishing period and 1.09 kg, 2246 DM and 4.99 kg DM when lasalocid was only fed during the grazing period. Daily gains of 1.05 and 1.06 kg were significantly lower (P less than 0.05) than 1.12 kg. Most carcass data were unaffected, except fatness. The permanent feeding of lasalocid increased carcass fatness, mainly as the result of a higher final weight.

Asunto(s)

RESUMEN

In a 14-week experiment beginning at week 4 postpartum, with 40 individually housed autumn calving cows a system of flat rate feeding (F) was compared with standard feeding (N). The basal ration consisted of a restricted amount of maize silage and ad libitum grass silage. Average daily concentrate DM consumed was 6.3 and 6.5 kg for treatment F and N respectively. Treatment F resulted in a non-significant higher forage DM intake. Covariant adjusted yields of milk (27.8 and 27.9 kg/d) and 4% fat corrected milk (28.3 and 28.3 kg/d) were not decreased by treatment F. The system of concentrate allocation had no effect on either milk composition or body weight changes. The results are discussed in relation to other data.

Asunto(s)

RESUMEN

Two trials were conducted with 32 and 39 finishing Belgian white-red bulls, treated with anabolic agents during 55 to 60 days prior to slaughter. Xenobiotic androgens and estrogens, together with (Exp. I) or without progesterone (Exp. II) were injected at three-week intervals. Diets consisted of maize silage and 7.5 g concentrate daily per kg liveweight. Half of the animals within each experiment received an antibiotic for the entire fattening period lasting about 285 days. Lasalocid-sodium (Exp. I) and virginiamycin (Exp. II) were incorporated at 65 mg per kg concentrate. Anabolic agents improved average daily gain from 1.06 to 1.20 kg (P less than 0.10) and from 1.24 to 1.42 kg (P less than 0.05) respectively. In both trials steroidal growth promoters stimulated intake and improved feed efficiency (P less than 0.10). Feed antibiotics did not significantly affect daily gain during this short term finishing period. A reduced feed intake (P less than 0.05) and improved feed conversion were observed for lasalocid, while there was no difference for virginiamycin. Dry matter intake amounted to 80.5 and 76.3 g per kg metabolic weight and 9.02 and 8.41 kg per kg gain, respectively for control and lasalocid treated animals. The data were 79.6 and 80.3 g and 7.30 and 7.34 kg, respectively, for the experiment with virginiamycin. No significant interaction between anabolics and antibiotics was obtained with respect to gain and feed efficiency. Dressing percentage, carcass composition, carcass grading and meat traits were not affected by anabolic treatment or antibiotic supplementation.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)