RAPE CAKE AS A RESIDUE IN PRODUCTION OF T HE BIO-OIL IN NUTRITION OF LAYING TYPE OF HENS

Rape cake as a residue in bio-oil obtained by cold pressing is a feed which has not been yet fully investigated. The work has been aimed at studying the nutritive value, dietetic properties, optimal representat ion in feed mixture for laying type of hens, the effect on production of eggs and their technological quality. Feed-balance trial has been c onducted with laying type of hens Shaver Starcross 288 at the age of 4 2 to 48 weeks which were placed individually in three-battery cages. T he trial consisted of the control group (n = 19) in which laying hens were fed with the feed mixture commonly used in production conditions HYD-10-KZ, and of two experimental groups (each of them had n = 24) wh ich were fed with the rape cake (Tab. I). The experimental group P-RV5 the feed mixture was added with 5% of rape cake and the experimental group P-RV10 consisted of 10 % rape cake. Goitrogenic action of rape c ake was reduced by fortification of the feed mixture by potassium iodi de (1 mg/kg of rape cake). Hens were fed ad libitum. Based on chemical analyses the nutritive value of rape cake and the content of natural hazardous substances was found, and the intake of feed, use of nutrien ts from feed, live weight of laying hens, egg production and technolog ical value of eggs. On the basis of excreted non-digested nutrients, n itrogen and phosphorus environment load was estimated. Rape cake is a protein feedstuff of high nutritive value (Tab. II), where the ratio b etween saturated and unsaturated fatty acids in them is 6.75 : 93.25. 1 kg of fat-free mass of rape oil seed cake contains 25.16 mmol glucos inolates and 11.62 mmol sinigrin (Tab. III). Of the other natural haza rdous substances it contains progoitrin, gluconapin, sinalbin and napo laifern. By administration of feed mixture with a ratio of 10 % rape o il cake the lower consumption of this feed mixture, crude protein, nit rogen-free extract, organic matter and total and non-phytate phosphoru s and raised intake of fat were recorded statistically confirmed (P < 0.05). Insignificant live weight gain 17.71 to 73.75 g was recorded du ring trials (Tab. V). In studying the retention of nutrients (Tab. VI) statistically significantly lower amount (P < 0.05) of nitrogen-free extract and organic matter retained in the body of laying hens by admi nistration of feed mixture with a ratio of 10 % rape cake. Higher egg- yield (Fig. 1) was recorded in experimental groups. Statistically sign ificant decrease in eggs (P < 0.05) was in the experimental group whic h was administered the feed mixture containing 10 % of rape cake. The quality of egg shell expressed in weight and share (Fig. 2) was not af fected by the investigated nutrition. By studying the environment load (Tab. VII) the differences in excretion of nitrogen in droppings amon g groups were not statistically confirmed. Statistically significant d ecrease (P 0.05) in amount of excreted phosphorus in droppings was rep orted in the experimental group in which the laying hens were fed with the feed mixture containing 5 % rape cake.