Opportunities of Genomics for the Use of Semen Cryo-Conserved in Gene Banks.

Shortly after the introduction of cryo-conserved semen in the main farm animal species, gene banks were founded. Safeguarding farm animal genetic diversity for future use was and is the main objective. A sampling of sires was based on their pedigree and phenotypic information.

The Use of Genomic Information for the Conservation of Animal Genetic Diversity.

The conservation of genetic diversity, both among and within breeds, is a costly process. Therefore, choices between breeds and animals within breeds are unavoidable, either for conservation in vitro (gene banks) or in vivo (maintaining small populations alive). Nowadays, genomic information on breeds and individual animals is the standard for the choices to be made in conservation.

Reducing inbreeding rates with a breeding circle: Theory and practice in Veluws Heideschaap.

Breeding circles allow genetic management in closed populations without pedigrees. In a breeding circle, breeding is split over sub-populations. Each sub-population receives breeding males from a single sub-population and supplies breeding males to one other sub-population.

Conservation priorities for the different lines of Dutch Red and White Friesian cattle change when relationships with other breeds are taken into account.

From a genetic point of view, the selection of breeds and animals within breeds for conservation in a national gene pool can be based on a maximum diversity strategy. This implies that priority is given to conservation of breeds and animals that diverge most and overlap of conserved diversity is minimized. This study investigated the genetic diversity in the Dutch Red and White Friesian (DFR) cattle breed and its contribution to the total genetic diversity in the pool of the Dutch dairy breeds.

Autologous and homologous transplantation of bovine spermatogonial stem cells.

The aim of this study was to develop a method for spermatogonial stem cell transplantation into the bovine testis. Five-month-old Holstein-Friesian calves were used and half of the calves were hemicastrated to allow autologous transplantation and the other half were used for homologous transplantation. Approximately 20 g of each testis was used for cell isolation.

Genetic correlation between days until start of luteal activity and milk yield, energy balance, and live weights.

The objective of this study was to estimate genetic correlations among fertility and measures of energy balance, dry matter intake, and live weight (change). Data from 622 first lactation cows (fed ad libitum a complete ration) included milk, fat, and protein yields; energy balance; and live weights for the first 15 wk of lactation. For a subset of the heifers (n = 329) and 91 contemporaries, progesterone values were measured in the milk twice a week and were used to determine the interval between calving and first luteal activity (CLA).

Effect of monensin on milk production by Holstein and Jersey cows.

Effects of the administration of monensin via concentrates to dairy cows were studied in two trials. In one trial, 64 Holstein cows were assigned to four groups that received 0, 150, 300, or 450 mg/d of monensin from 5 to 24 wk postpartum. Milk production tended to increase (4.

Effects of treatment of dairy cows with recombinant bovine somatotropin over three or four lactations.

Jersey, Dutch Red and White, and Friesian cows were subcutaneously injected with 640 mg of recombinant bST at 28-d intervals from 87 to 115 d after calving through four successive lactations. A TMR (6.72 MJ of NEL) and 168 g of CP/kg of DM) was fed for ad libitum consumption.

[Effects of long-term BST application in dairy cows].

The effects of administration of BST on milk production of dairy cows are summarised on the basis of a number of review papers. Then the results of a trial with forty control cows and thirty-seven cows, in which six doses of 640 mg of BST were subcutaneously injected at twenty-eight day intervals from the fourth month after calving in a third of fourth lactation are discussed. The response to administration of BST was a 3.

[A comparison between large breeds of cattle and their cross-breeds with Jerseys].

Friesians (ZB) and MRY cows were inseminated with semen from Jersey or Holstein Friesian (ZB) and Jersey or MRY bulls respectively. The Jersey x Friesian (J x ZB) and the Jersey x MRY (J x MRY) crossbreds were compared with their contemporary Friesian and MRY herdmates, respectively. Crossbreds were born without any calving problems.

[Effect of BST administration on milk production and metabolism of dairy cows in 3 consecutive years of IVO trials(Institute for Animal Husbandry Research)].

The effect of subcutaneous administration of recombinantly derived bovine somatotropin (somidobove) in a sustained delivery vehicle was studied in three successive lactations. After a preliminary period of three months, cows of different breeds and parities were treated during six periods of treatment of 28 days. The efficacy of BST application was equal in Jerseys (n = 35), Red and Whites (n = 54) and Friesians (n = 149); was slightly higher in cows (n = 211) than in heifers (n = 32); was higher on concentrates- (n = 105) than on roughage (n = 138) based diets and was slightly lower in a third successive lactation.

[Breed variations in feed intake and energy utilization in dairy cows].

In four experimental studies on feed intake, two completely mixed rations containing 0 and 50 per cent of concentrates respectively were fed ad lib. to dairy cattle of four different breeds: the Jersey, the Holstein-Friesian (HF), the Dutch Black-and-White (FH) and the Dutch Red-and-White (Meuse-Rhine-Yssel). There are considerable differences in feed intake between the breeds, particularly between the Jerseys and the heavier breeds (HF + MRY + FH).

[Direct selection for fertility and health in cattle].

Financial losses in dairy cattle due to breeding inefficiency and health impairment are so high that they should be taken into account in cattle breeding. These disturbances tend to increase as productivity increases. Although these disturbances are quantitative characteristics, they can only be recorded qualitatively.

Differences in mastitis susceptibility between Holstein Friesian, Dutch Friesian and Dutch Red and White cows. Correlation between parameters for mastitis and for production.

On an experimental farm 3 dairy breeds were compared with regard to mastitis by various parameters. Higher cell counts and more udder infections were present in the Dutch Red and White (DRW) in comparison with the Holstein Friesian (HF) and the Dutch Friesian (DF). Within the HF breed a negative correlation between cell count and production was established and also in this breed, a negative correlation between maximum rate of milk flow and cell count.

Differences in mastitis susceptibility between Holstein Friesian, Dutch Friesian and Dutch Red and White cows.

Summary On an experimental farm 3 dairy breeds were compared with regard to mastitis by various parameters. Higher cell counts and more udder infections were present in the Dutch Red and White (DRW) in comparison with the Holstein Friesian (HF) and the Dutch Friesian (DF). Within the HF breed a negative correlation between cell count and production was established and also in this breed, a negative correlation between maximum rate of milk flow and cell count.

Fertility control in cattle by use of the "milk progesterone test".

The development and validation of a radioimmunoassay for progesterone in cow's milk is described. Control of the temperature during storage of the milk and also during the sample incubation procedure appeared to be a critical requirement with respect to reduction of nonspecific binding of tritiated progesterone. Ranges of milk progesterone levels were established during pregnancy as well as during the luteal and the follicular phase of the oestrus and of pregnancy in three trials on two experimental farms.