Variations in the milk yield and milk composition of dairy cows during lactation.

Variations in the milk yield and milk composition of a dairy cow colony (n = 23) were analyzed during 11 months of lactation. Milk yield followed a characteristic decreasing pattern in negative correlations with solid components (milk protein, lactose, total solids, milk fat). Titrable acidity (degree SH) was significantly (p < 0.1) higher in the milk of fresh-milking cows and it correlated negatively with lactose and positively with milk protein, milk fat and total solids. The concentrations of Zn, Fe and Cu tended to decrease, while Mn showed insignificant variation during lactation. Milk vitamin A showed a significant positive whilst milk vitamin E had a negative correlation with milk fat.

Variations in the yield, composition and somatic cell count of ewe's milk during lactation.

Variations in the yield, composition and somatic cell count of milk were studied in 30 grazing ewes, representing the Pleven F1 x East-Friesian Blackface, Pleven F1 and Merino genotypes, during five months of lactation. The somatic cell count (SCC) correlated negatively with milk yield and lactose whilst positively with milk protein and milk fat, except for Pleven F1 ewes which showed these correlations with reversed values. The highest milk yield with the lowest SCC was shown by the Pleven F1 x East-Friesian Blackface genotype. Lactose concentration varied in a significant negative correlation with the neutral detergent fibre content of the grass.

Variations in milk somatic cell count and haematologic values of dairy cows during lactation.

Variations in milk somatic cell count (SCC) and haematologic values were studied in a dairy cow colony of the Holstein-Friesian and Hungarian Red-Spotted breeds (n = 23) from May 1992 to July 1993. Milk and blood samples were taken approximately at monthly intervals and data were assigned into ten lunar months of lactation. After a maximum in month I, SCC dropped abruptly in month II and continued to decline through the subsequent four months, then it again tended to increase through months VII-X. The SCCs varied within the physiological range throughout the lactation period parallel with red blood cells and white blood cells constituting a major segment of the somatic cell population. Positive correlations were recorded between SCC and the blood variables (packed cell volume, red blood cell count, white blood cell count). The lactation pattern of SCC was comparable to previous observations.

Blood glutathione peroxidase enzyme activity as an index of selenium release from Permasel in ewes.

Ten Merino ewes were given a single Permasel pellet (containing 5% of elementary selenium) orally and examined for the release of selenium in the reticulum by determining glutathione enzyme activity of the whole blood haemolysate over a period of 12 months. As compared to the controls, the treated ewes exhibited a significant elevation in glutathione peroxidase activity for 8 months, indicating an acceptable persistence of the product tested.

[Influence of various feedstuffs containing fat and protein on the nitrogen metabolism of calves]. / Einfluss von verschiedenen fett- und eiweisshaltigen Futtermitteln auf den Stickstoffumsatz bei Kälbern.

Experiments concerning the nitrogen metabolism of 3-, 5-, 7-, 9-, and 11-week-old calves were carried through. The calves were daily fed 146, 219, 323 g milk replacer and differing amounts of dried skim milk (697, 761, 717, 723, 653 g). Energy consumption was dependent on the consumption of milk replacer. With increasing age, N-digestibility and N-retention from the feedstuffs diminished gradually. The smallest decrease of N-retention was observed with those animals receiving the highest amount of milk fat energy. The decrease of nitrogen digestibility can be attributed to the higher consumption of plant feedstuffs and the decrease of the biologic value of the protein. The experiments concerning the nitrogen metabolism show that a higher dosage of fat had a favourable influence on nitrogen retention. At an age of between 7 and 9 weeks correlation coefficients of between +0.50 and +0.36 were ascertained between the fat content of the feed ration and nitrogen retention. At the same age correlation coefficients of +0.60 resp. +0.53 were ascertained between the energy content of the ration and nitrogen retention. These investigations are the basis for the statement that for the nitrogen retention of calves at the age of 7 to 9 weeks feed energy (fat) is the most important factor. A close positive correlation could be observed between the crude protein consumed with the feed ration and the amount of digested nitrogen. Moderately positive correlation coefficients were calculated between the amount of nitrogen taken in resp. the amount of digestible nitrogen and the assessed amount of nitrogen at the age of 7, 9 and 11 weeks. The experiments with the nitrogen metabolism are the basis for the statement that protein and fat together determine the amount of nitrogen retention for calves fed wth moderate milk protein. For calves fed with less milk protein, 23 to 34% fat in the dry matter of the milk replacer proved to be successful. The favourable effect of a higher amount of milk replacer on nitrogen retention can also be attributed to the higher amount of chemotherapeutic sustances (vitamins, antibiotics) taken in with the milk replacer.

[The influence of various feedstuffs containing fat and protein on the digestibility of crude nutrients in young calves]. / Der Einfluss von verschiedenen Fett- und eiweisshaltigen Futtermitteln auf die Verdaulichkeit der Rohnährstoffe bei jungen Kälbern.

Digestibility trials were carried out with calves, aged 3, 5, 7, 9, and 11 weeks, which were fed with feedstuffs of various energy and protein levels (various amounts of dried skim milk supplement with 146, 219, 323 g per day of the milk replacer Laktin) plus concentrate and hay. The purpose of the experiment was to find out what effect the amount of milk replacer varying daily had on the digestibility of the nutrients. The experiments confirm that the amount of milk replacer has a great influence on the digestibility of the crude fat. The amount of digestible crude fat consumed with the feed considerably influcenced the digestibility of the energy, it had little influence on the digestibility of the other nutrients, however. With increasing age the calves received more plant protein sources with a lower biologic value. Thus the digestibility of the protein in the complete ration was diminished as well. This shows that the digestibility was influenced by the protein quality, not, however, by the amount of crude protein. The digestibility of the dry matter andthe organic matter as well as of the N-free extractives in the feed ration diminished according to the changed composition with the increasing age of the animals; in constrast to this the digestibility of the crude fibres increased gradually.

[The digestibility of milk substitutes with various soybean products in young calves]. / Verdaulichkeit von Milchaustauschern mit verschiedenen Soja-Präparaten bei jungen Kälbern.

Digestibility trials were performed to study the suitability of mixtures made up of treated soybean and whey powder for replacing skim milk powder. Three different milk replacers were used, the replacers T-18/II and T-18/III containing Plyllac preparations manufactured by different technologies. When using the T-18 preparation with 18% fat content it was found that the protein source may contain 25% Plyllac preparation and 11% sweet whey powder. In two cases, at the age of 5 and 7 weeks, the digestibility of the crude protein in the T-18/II preparation was found to deteriorate significantly. For this reason, the authors suggest this milk replacer to be used from the 5th week of life. Trials were performed with 3 milk replacers (lactine preparations) containing Plyllac preparations of different manufacturing technology (35%), treated soybean (10%) and sweet whey powder (10%). It was found that the use of Plyllac preparations, i.e. of treated soybean in larger amounts causes the nutrient digestibility, mainly that of crude protein, to be significantly lower at the age of 3 and 5 weeks than that at the age of 7 to 9 weeks. No significant differences were found in the digestibility of the various Plyllac preparations manufactured by different technologies. The milk replacer lactine is recommended for use from the 5th week of life on.

[Effect of milk substitutes with various soy bean products on the N metabolism in calves]. / Einfluss von Milchaustauschern mit verschiedenen Soja-Präparaten auf den N-Umsatz von Kälbern.

N-balance trials on young calves aged 3, 5, 7, 9 and 11 weeks, respectively, revealed that a mixture of soybean and whey powder accounting for 39.5% of the total protein amount can be fed without any disadvantage. Feeding this mixture gave N-balance results differing only slightly in the groups aged 7, 9 and 11 weeks. The milk replacer with a higher proportion of soybean and whey powder revealed a more unfavourable N-balance. This allows to conclude that milk replacers containing soybean preparations can be successfully applied to young calves from 5 weeks on, no disadvantages being likely as to N-balance and live weight gain.

[Influence of milk-fat substitute feeding on the metabolism in calves]. / Einfluss der Fütterung von Milchfettaustauschern auf den Stoffwechsel von Kälbern

Investigations were made to study the effect of milk fat substitutes ("Laktin", "TZS-60") on the metabolism of 3 and 5-weeks-old calves. "Laktin" is prepared from lard and hydrogenated soya and fish oil; additionally, it contains lecithin, monoglycerides, antioxidants, vitamins and antibiotics. "TSZ-60" is a preparation containing starch and colloidal silicic acid as carrier material mixed with 60% of coarsely powdered fat (particle sizes ranging from 50 to 200 mum), which in turn, is supplemented with vitamins and antibiotics. The kinds of "Laktin" used in the present trial contained 95%, 58%-98% or 90% of fat while "TSZ-60" contained 59.4%. Both the 3-weeks-old and the 5-weeks-old calves digested the "Laktin" fat more efficiently than the kind of fat contained in "TSZ-60" ("Laktin": 94.3% to 97.3% of fat; "TSZ-60" 71.8% to 90.5%). As a consequence of this, the "Laktin"-fed calves exhibited a higher rate of nitrogen utilization and nitrogen retention. According to the results obtained in the present trial "Laktin" should be given in daily doses of 219 g (an amount corresponding to 7 litres of milk with a milk fat content of 3.13%) while "TSZ-60" should be fed in daily amounts of 245 g (corresponding to 7 litres of milk with a milk fat content of 2.1%). Higher doses ("Laktin": 323 g/day: "TSZ-60" 335 g/day) would have a detrimental effect on the metabolism of the calves. Apart from this, it was not found that higher doses would help to reduce the protein consumption of the animals.

[Studies of the methods used for the determination of the digestibility of crude fats in calves]. / Methodische Untersuchungen zur genauen Bestimmung der Verdaulichkeit des Rohfettes bei Kälbern

An investigation was made of methods used for the exact determination of the crude content and crude extract of faeces. The following methods were examined: (1) Following treatment with hydrochloric acid a 1:1 mixture of ether and petroleum ether was used. (2) Following hydrolysis with hydrochloric acid extraction with ether was carried out immediately from the aqueous phases. (3) The analysis was carried out with Folch's solvent. A 1:1 mixture of methanol and chloroform was used. (4) The faeces were dried with infrared lamps and crude fat extraction was carried out with Folch's solvent. A 1:1 mixture of methanol and chloroform was used. (5) The faeces were dried with infrared lamps and extraction with ether was done in a Soxhlet apparatus. Nearly identical results were obtained with methods 1 and 2 or 3 and 4 in determining the content of crude extract, the acid number and the percentage proportion of fatty acids. Essential differences were found between methods 1 and 2 and methods 3 and 4. The most reliable results were obtained by using method (2). Method (5) was found to be most suitable for large-scale testing. Values for the content of crude extract in the faeces were somewhat lower (0.78%-1.2%) when determined by method (5). These variations were not significant statistically. (P greater than 5%). No significant differences were observed between methods (2) and (5). It was thus established that method (5) is best suited for estimating the crude extract of the faces. The faeces of calves were found to contain a high proportion of unsaponifiable matter. This proportion was subtracted from the percentage of crude extract and the amount of faecal crude fat was thus estimated. Very small but statistically significant differences were found by converting digestibility data of crude extract into those of crude fat. Hence, for future work the most appropriate method appears to be the estimation of the crude extract in feedingstuffs.