POSSIBILITIES FOR IMPROVING MILK YIELD AND FAT AND PROTEIN CONTENT WITH SELECTION

J. POGAČAR^a)
a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: Slovene

ABSTRACT
Traits have different economic importance and different genetic variation. Some of them are antagonistic, i.e. milk yield and meat production, milk yield and protein content etc. These are the reasons why to use the selection index as the optimal selection strategy. Selection index, defined as the maximum income, is constructed under the consideration of different traits and their different economic weights dependent from the market situation. Model calculations show that from the economic point of view a simultaneous selection on fat and protein yield is the most successful. Selection strategies that consider only the fat content or only the protein content are economically insufficient.

MILK PROFILE TEST - A TWO-YEAR EXPERIENCE

T. ZADNIK^a), Marija KLOPČIČ, A.PENGOV
^a) Univ. of Ljubljana, Vet. fak., Gerbičeva 60, SI-1000 Ljubljana, Slovenia

Professional paper
Language: Slovene

ABSTRACT
For the detection of most frequent herd production diseases bulk milk samples proved as an effective orientation-diagnostic material which is in comparison to blood analysis much cheaper and its use quick and simple. The results of the analyses of the common milk sample enable the determination of the nutritional and health status of the herd. Discussion with the producer, further analyses of husbandry measures, clinical examination of animals, blood and milk samples ensure an adequate management of the herd. Our findings are based on the evaluation of 1547 weekly bulk milk samples. Milk samples from four regions in Slovenia were weekly collected on 30 farms in 1993 (n=12) and in 1994 (n= 18) and analyzed for fat, protein, lactose, urea, sodium, potassium, acetone concentrations and somatic cell count. A coefficient between fat/protein and protein/urea was also calculated. The model of multiple analyses of variance revealed that the results of milk analyses were statistically significantly (P<0,05) influenced particularly by the year of the investigation, farm, season (winter-summer feed intake) and to a lesser extent (P>0,05) by the health status of the udder (SCC x1000/ml) and ketolactia. The results of the milk profile test provide a useful material for the producers as well as any specialists involved in dairy industry.

ESTIMATING BREEDING VALUES FOR MILK TRAITS WITH AN ANIMAL MODEL IN THE SLOVENIAN SIMMENTAL BREED

Elizabeta Špela MÖNIG^a)
a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Original scientific paper
Language: Slovene

ABSTRACT
The standard model for estimating breeding values nowadays is the animal model. The breeding values are adjusted for the genetic merit of relatives and mates. An animal model can account for multuple traits. Male and female animals are evaluated jointly. One direct use is in calculation of future production of an animals relative to the genetic base so the generation interval becomes shorter. Breeding values were estimated in the slovenian Simmental breed (N=49593; 200 bulls) for 15 years (1975-1990) with a BLUP-sire model which is the standard model in Slovenia and a BLUP-animal model. In comparison with the BLUP-sire model the mean animal model breeding values for milk yield and fat yield are much lower. Also the genetic standard deviation is very low with the animal model. The correlation between breeding values estimated with the two models is very high. The means there are no important changes in the range list of bulls. The genetic gain in the 15 years calculated with the animal model is very low for both traits for cows and bulls. Some correlation factors should be estimated to adapt the model better on the slovenian conditions and great attention should be focused on the data quality specially the pedigrees for the further work with the animal model.

A DESCRIBE OF AP CONTROL PROCESS FROM COMPUTER POINT OF VIEW

Anka DOLINAR^a), J. POGAČAR, Marija KLOPČIČ
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Professional paper
Language: Slovene

ABSTRACT
There were made some computer programs for update and quick attending of milk production of cows included in AP control. Those programs enable not only diferent control of data at the input and during the other process but also a lot of different output which enable breeders to attend to milk production of every single cow and also of whole herd. For their work, computer programs need basic data base from which they get data. The slowly growing data base affects the speed of those programs. In the future the development will base on as much as possible automatical input of data into the computer and on connection of different computers.

MILK PROTEIN GENES: A MOLECULAR APPROACH

P. DOVČ^a), J.F. MEDRANO
^a) Univ. of Ljubljana, Biotechnical Fac., Zootechnical Dept., Groblje 3, SI-1230 Domžale, Slovenia

Review paper
Language: Slovene

ABSTRACT
Modern trends in selection of dairy cattle are geared towards higher solids content and better technological properties of milk because of the increasing proportion of milk being used for manufacturing. Protein content in milk is a quantitative trait with a very complex genetic mechanisms involved in it’ s regulation. Cluster of four casein genes and genes for two major whey proteins (a -lactalbumin and b -lactoglobulin) represent genomic coding regions for the major bovine lactoproteins. All are present as allelic variants, which have a qualitative but also quantitative effect on the protein content of milk. Polymorphisms between allelic variants are present within coding regions and also within regulatory regions of milk protein genes, having a regulatory effect on gene expression at the transcriptional and post transcriptional level. Differential allelic production has been demonstrated for k - casein and b -lactoglobulin genes. Study of different promoter regions from milk protein genes offers information about the molecular mechanisms regulating milk protein synthesis. The search for the major loci involved in the regulation of milk production revealed some regions within the genome related with the milk yield. This molecular data can be used for marker assisted selection and biotechnological modifications of milk components.

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