The effect of urea on the voluntary intake by calves of silages preserved with formaldehyde and formic acid

Perennial ryegrass cv. S23 was preserved by fermentation (C), or with the addition of 8.7 1 formalin (35% w/w formaldehyde) per t fresh herbage (F) or of 9.0 1 equal mixture (by vol.) of formalin and formic acid (85% w/w solution) per t fresh herbage (FF). These three silages comprised the treatments in a three-period, crossover design in which urea (u) was given at the rate of 20 g per kg dietary DM to half the animals. Twelve calves were allocated to the treatment sequences when they were approximately 12 weeks of age from within groups which had previously received diets with or without urea. Calves ate significantly (P< 0.001) less of silages F or FF than of silage C when each was offered alone, but when urea was given, intakes of silages F and FF were significantly (P < 0.001) increased such that the intakes of all three silages with urea were similar (23.6, 19.6, 19.3, 24.2, 24.2, 24.7 ± 0.51 g DM per kg LW for C, F, FF, Cu, Fu and FFu, respectively). Significantly (P<0.01) more of the DM in silage C was digested than in F or FF and the addition of urea significantly (P<0.05) increased the digestibility of DM from silage FF only (73.8, 71.3, 69.8, 74.6, 70.7, 72.5 ± 0.72% for C, F, FF, Cu, Fu and FFu, respectively). When the silages were given alone, calves spent longer eating and ruminating per kg DM ingested with F or FF than with C. The time spent on F and FF was significantly (P<0.01) reduced by the addition of urea (303, 388, 411, 297, 299, 290 ± 18.9 min per kg DM ingested for C, F, FF, Cu and Fu and FFu, respectively). The results presented suggest that urea partially alleviated the reduction in voluntary intake by calves given herbage preserved using formalin, but the mode of action was not clear.     

THE ERROR IN PREDICTING PASTURE DRY–MATTER DIGESTIBILITY FROM FOUR DIFFERENT METHODS OF ANALYSIS FOR LIGNIN

The lignin content of 50 samples of five grasses of known in vivo digestibility were determined by the methods of Armitage, van Soest and two modifications of the van Soest technique. The error in predicting DM digestibility varied from ±3.1 for tbe Armitage metbod to ±5.0 for the van Soest method. This error compares nnfavourably witb ±2.1 previonsly obtained on tbe same samples with the in vitro technique of Tilley and Terry.     

Experimental hybridization in certain diploid mexican solanum species

S. bulbocastanum is highly interfertile with S. cardiophyllum. Through the F₁ to F₅ little breakdown due to sterility or lack of plant vigour occurred. F₁ plants of a 5-species hybrid involving S. pinnatisectum, S. trifidum, S. jamesii, S. bulbocastanum, and S. cardiophyllum could also be intercrossed. One-way compatibility was frequently expressed in progenies of these interspecific crosses. It appears to be cytoplasmically controlled, although nuclear factors may be present which interact with cytoplasmic factors. The group of Mexican diploid potatoes represented by these species is potentially interbreeding and shows evidence of introgression throughout its range in central and Western Mexico.Contribution No. 169, Canada Department of Agriculture Research Station, Fredericton, New Brunswick, Canada     

LOSSES IN THE CONSERVATION OF HEAVILY-WILTED HERBAGE SEALED IN POLYTHENE FILM IN LINED TRENCH SILOS

A conservation experiment is described in which the losses in ensiling heavily-wilted herbage, of approximately 50% dry matter, in lined trench silos, with and without a polyethylene film seal, are compared. The composition and digestibility of the silages produced in the sealed silos were comparable with those of the original herbage. The content of organic acids in the sealed silos was low, suggesting that fermentation was suppressed by the partially gas-tight seal. In the unsealed silos there was considerable spoilage, 70% of the material being inedible. In the 2 sealed silos losses of dry matter were 8·2 and 5·2% and losses of SE 11·5 and 7·8%, respectively. The losses recorded are compared with those usually encountered in lined trench silos.     

Heritable necrosis of red storage cabbage

Research was carried out on heritable necrosis of red storage cabbage. Susceptibility to this type of necrosis depends on 1 incompletely recessive factor n. NN-plants always remain healthy, whereas the majority of the nn-plants become necrotic shortly after the harvest. A number of the Nn-plants also show (mostly weak) symptoms in the second half of the storage period. Minor genes may have an effect as well.Selection for resistance to necrosis should be carried out as late as possible, preferably at the end of the storage period.

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Samenvatting Onderzoek vond plaats over erfelijke necrose bij rode bewaarkool. De gevoeligheid voor dit verschijnsel wordt bepaald door 1 onvolledig recessieve factor n. N N-planten blijven steeds gezond, terwijl de meeste nn-planten korte tijd na het oogsten necrotisch worden. Bij een deel van de Nn-planten treden in de tweede helft van de bewaar-periode dat ook andere genen op resistentie tegen necrose nog een geringe invloed hebben.Voor de selectie op resistentie tegen necrose is hetvan belang dat deze zo laat mogelijk uitgevoerd wordt, dus bij voorkeur aan het eind van het bewaarseizoen.