Lucerne (Medicago sativa L. var. Palava), harvested at four successive dates over a 30-day period, was evaluated for chemical composition (dry matter, organic matter, crude protein, ether extract, crude fibre, nitrogen-free extract, neutral detergent fibre, acid detergent fibre, acid detergent lignin), amino acid contents and intestinal digestibility in dairy cows. Dry matter (r = 0.78), organic matter (r = 0.95), crude fibre (r = 0.91), neutral detergent fibre (r = 0.94), acid detergent fibre (r = 0.79) and acid detergent lignin (r = 0.48) presented positive linear correlation coefficients (r) with growth stage, whereas crude protein (r = -0.96), ether extract (r = -0.86) and nitrogen-free extract (r = -0.70) showed negative relationships. Total essential amino acid content decreased (r = -0.94) from 84.1 to 55.3 g/kg of dry matter with maturity, with r-values higher than -0.90 obtained between growth stage and contents of lysine, methionine, threonine and valine. With the exception of tyrosine (r = -0.68), r-values between growth stage and individual non-essential amino acids were all higher than -0.90. Total amino acid (r = -0.98) and nitrogen (r = -0.99) contents presented comparable tendencies with successive sampling times. Whereas no definite trends were detected for the amino acid composition of rumen incubated (16 hours) lucerne samples, the intestinal digestibility of total essential (r = -0.78), total non-essential (r = -0.58) and total (r = -0.69) amino acids as well as nitrogen (r = -0.99) decreased with growth. However, due to a small sample size (n = 4), most linear relationships between constituents and growth stage were insignificant. It can be concluded that, although limited in the sample size, this report presents information on the decrease in amino acid contents and intestinal amino acid digestibility as growth proceeds in lucerne (var. Palava) produced in the Czech Republic, which could be utilized in the feeding of ruminants.
Method according to DIRSTINE (1968) was employed to study the activities of serum and liver lipase in White Leghorn cockerels during early post-incubation ontogenesis; as to serum lipase, two embryo intervals were also studied (the 13th and 20th day of incubation). From the average value of 4.4 ummol (13th day), serum lipase activity increased to the average value of 7.5 ummol (20th day). The first day after hatching the average value was 3.5 ummol which remained almost unchanged until the 9th day, with the exception of a slight drop the third day; an increase of activities was observed on the 13th day (4.9 ummol), 15th day (3.5 ummol), 21st day (7.6 ummol), 22nd day (5.5 ummol), and 24th day (8.8 ummol). The minimum average activity of 2.5 ummol was measured the 32nd day. Liver lipase activity was observed to drop from the first-day starting value of 20.6 ummol to 9.8 ummol (the second day), with a subsequent increase to 14.9 ummol (the 4th day). The maximum values were recorded the 13th day (26.2 ummol) and the 15th day (28.7 ummol) whereas the minimum average value was obtained the 32nd day (6.3 ummol). Liver lipase activity drop on the second day of age and serum lipase activity drop on the third day with subsequent increase are probably associated with the change from yolk-sac nutrition to feeding per os. Some stabilization of serum and liver lipase occurs the 32nd day; the values found in adult fowl were almost the same as the 32nd day values.
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