The effect of low-density diets on broiler breeder performance during the laying period and on embryonic development of their offspring.

The effect of low-density diets on bird performance, egg composition, and embryonic development was studied with 2,100 female and 210 male Cobb broiler breeders from 25 to 60 wk of age. The experiment included 5 treatments. These included a control group with a normal density diet (ND, 2,800 kcal of AME/kg).

Associations between energy metabolism, LH pulsatility and first ovulation in early lactating cows.

This study was designed to elucidate associations between energy metabolism and LH pulsatility characteristics in early lactation, and days to first ovulation, in order to explain the relationship between energy balance and fertility observed in epidemiological studies. To this end, 10 multiparous HF cows were monitored during lactation, after the application of two different feeding strategies during the dry period. Days to first ovulation was assessed using blood progesterone measurements and LH pulsatility was measured in 8-h windows in the third week postpartum.

Effects of non-esterified fatty acids on bovine granulosa cells and developmental potential of oocytes in vitro.

High yielding dairy cows experience a negative energy balance (NEB) shortly after parturition, which is accompanied by high concentrations of non-esterified fatty acids (NEFA) in blood up to approximately 3 weeks post partum. We hypothesized that the elevated plasma NEFA concentration causes lower fertility by exerting negative effects on granulosa cells and oocytes in the ovary, leading to less viable embryos and insufficient corpora lutea. In two series of experiments, we studied the effects of a realistic NEFA (C18:1) concentration on both the proliferation and the progesterone production of follicular granulosa cells in vitro (part I) and on maturation, fertilization and developmental potential of oocytes (part II).

Follicular dynamics around the recruitment of the first follicular wave in the cow.

The present study aimed to test the generally accepted view that a follicular wave starts with follicles newly recruited from the population smaller than 3 mm, which later compete for dominance. According to this view, subordinate follicles are expected to be too atretic to join the next follicular wave. Ten cows were ovariectomized shortly prior to the LH surge, thus around the start of the first follicular wave of the cycle.

Acute fasting in heifers as a model for assessing the relationship between plasma and follicular fluid NEFA concentrations.

It is known from epidemiological studies that negative energy balance in early lactating dairy cows is related to a depression in reproductive performance. Elevated plasma concentrations of non-esterified fatty acids (NEFA) are a typical metabolic characteristic of these animals and are proposed as the possible link. The suggestion is that NEFA might have a direct effect on the ovary, by affecting development of the oocyte or the granulosa cells.

Metabolic changes in early lactation and impaired reproductive performance in dairy cows.

This review addresses the suggestion that the decline in dairy reproductive performance, as increasingly observed these days, may be due to a hampered process of metabolic adaptation in early lactating cows. In our opinion, adaptation to the negative energy balance is a gradual process. Because almost all cows do adapt in the long run, it is not possible to classify animals as adapted or non-adapted.

Lack of association of Mycobacterium avium subsp. paratuberculosis with oocytes and embryos from moderate shedders of the pathogen.

Paratuberculosis is a chronic and progressive disease of the intestine in ruminants caused by Mycobacterium avium subsp. paratuberculosis (Map). The bacterium is transmitted to young animals, becomes manifest in adulthood and leads to economic losses.

Robotic milking and its effect on fertility and cell counts.

The aim of this study was to analyze the effect of robotic milking (RM) on fertility and somatic cell counts (SCC) among dairy herds participating in the national Dutch milk recording system. It was hypothesized that RM, and a higher milking frequency in general, would have negative effects on fertility, due to expected and supposed deeper negative energy balance (NEB). Herds increasing milking frequency from two to three times daily consistently had increased production.

Cellular and molecular deviations in bovine in vitro-produced embryos are related to the large offspring syndrome.

The large offspring syndrome (LOS) is observed in bovine and ovine offspring following transfer of in vitro-produced (IVP) or cloned embryos and is characterized by a multitude of pathologic changes, of which extended gestation length and increased birthweight are predominant features. In the present study, we used bovine blastocysts to analyze cellular parameters, i.e.

[Case report of a granulosa-theca tumor in a cow].

A 2 year-old cow with abnormal behaviour was observed during a farm visit. Rectal palpation of the cow revealed the presence of a mass of at least 12 cm in diameter. After further examination, it appeared that 'ovarian tumour' was the most likely differential diagnosis.

Effects of in vivo prematuration and in vivo final maturation on developmental capacity and quality of pre-implantation embryos.

In current in vitro production (IVP) systems, oocytes lack in vivo dominant and preovulatory follicular development, which may compromise pregnancy and viability of calves born. When an oocyte sets off in vivo on the road toward fertilization, it contains numerous transcripts and proteins necessary to survive the first few cell cycles of embryonic development. It is not yet known during which period of development the oocyte builds up the store, possibly primarily during the major growth phase of the oocyte, which is completed at the time a follicle reaches the size of 3 mm.

Effect of urea during in vitro maturation on nuclear maturation and embryo development of bovine cumulus-oocyte-complexes.

High concentrations of urea in reproductive tract fluids are detrimental to bovine reproduction. Therefore, in experiment 1, the effect of 6 mM urea on nuclear maturation of cumulus-oocyte-complexes (COC) collected from abattoir ovaries was studied. After 4, 8, 12, 16, 20, and 24 h of in vitro maturation, the nuclear stages of samples of the COC were determined.

Transgenesis may affect farm animal welfare: a case for systematic risk assessment.

This paper considers (potentially) harmful consequences of transgenesis for farm animal welfare and examines the strategy of studying health and welfare of transgenic farm animals. Evidence is discussed showing that treatments imposed in the context of farm animal transgenesis are by no means biologically neutral and may compromise animal health and welfare. Factors posing a risk for the welfare of transgenic farm animals include integration of a transgene within an endogenous gene with possible loss of host gene function (insertional mutations), inappropriate transgene expression and exposure of the host to biologically active transgene-derived proteins, and in vitro reproductive technologies employed in the process of generating transgenic farm animals that may result in an increased incidence of difficult parturition and fetal and neonatal losses and the development of unusually large or otherwise abnormal offspring (large offspring syndrome).

Bovine cumulus-oocyte-complex-quality is reflected in sensitivity for alpha-amanitin, oocyte-diameter and developmental capacity.

The aim of the present study was to find more parameters to define developmental competence of cumulus-oocyte-complexes (COCs). Bovine COCs were divided into five groups based on their morphology. In order of increasing level of atresia: COC-A had a bright, compact cumulus investment; COC-B1 also had a compact cumulus investment, but was darker than COC-A; the color of COC-B2 was comparable with COC-B1 but the corona radiata appeared to dissociate from the rest of the cumulus investment; the cumulus of COC-B3 was almost black and the corona radiata was almost completely dissociated from the rest of the cumulus investment; COC-C had a strongly expanded cumulus investment with dark spots of degenerated cells.

Altered functional and immunophenotypical properties of neutrophilic granulocytes in postpartum cows associated with fatty liver.

The intention of the study was to analyze the relationship between liver triacyl glycerol content (liver TAG content) and immunophenotypical and functional properties of polymorphonuclear neutrophilic granulocytes (PMN) of dairy cows in the peripartum period. We investigated characteristics of bovine PMN from the blood and uterus of clinically healthy cows in the periparturient period. The numbers of circulating leukocytes and segmented granulocytes continuously increased until parturition and declined afterwards to starting values.

Relationship among estradiol, cortisol and intensity of estrous behavior in dairy cattle.

Economic profitability of a dairy farm is based, in part, on the calving interval of the cows. The optimal interval is 365 d. To achieve this, the cow needs to be pregnant within 85 d post partum.

Robot milking and effect on reproduction in dairy cows: a preliminary study.

The aim of this study was to analyse whether automatic milking has an effect on reproduction in dairy cows. Probably the most important consequence of automatic milking is an increased milking frequency. More frequent milking means more production and thereby an extra threat for the energy balance during the first months of lactation.

Effect of ovarian phase and follicle quality on morphology and developmental capacity of the bovine cumulus-oocyte complex.

In order to study the effect of the follicular environment on the quality and developmental competence of cumulus-oocyte complexes (COC), COC were collected from nonatretic (NA), light atretic (LA), atretic (A), and heavily atretic (HA) follicles. Cumulus-oocyte complexes were also collected from early-luteal phase ovaries (EL), from late-luteal phase ovaries (LL), from follicular phase ovaries (F), and from ovaries from non-cyclic animals (NC). Each COC was assigned to one of three quality groups based on the appearance of the cumulus investment: 1) COC-A: compact and bright, 2) COC-B: less compact and dark, and 3) COC-C: strongly expanded cumulus with dark spots.

Environment of oocyte and embryo determines health of IVP offspring.

In vitro embryo production (IVP) enhances the number of offspring from a single female and offers the possibility of accelerated genetic progress in animal husbandry. However, it also leads to a low but unacceptable percentage of anomalies in the offspring. The aim of this paper is to introduce the three speakers at this afternoon session who will speak about the demands of culture conditions and the endometrial environment to support normal embryonic development without effects on the embryonic genome.

Relationship between triacylglycerol concentration in the liver and first ovulation in postpartum dairy cows.

The relationship between accumulation of triacylglycerols in the liver and first ovulation post partum was studied in an experiment with 32 dairy cows. During the dry period, 16 treated cows were fed a high energy diet to induce overconditioning, while 16 control cows were fed a recommended diet. After parturition, the treated cows entered deeper negative energy balance state, required more days to reach the nadir of negative energy balance, required more days to regain positive value of energy balance, and lost more body weight than the control cows.

Pregnancy diagnosis in sows: direct ELISA for estrone in feces and its prospects for an on-farm test, in comparison to ultrasonography.

The usefulness of fecal estrone (E1) measurement as a tool for pregnancy diagnosis was investigated. Concentrations of E1 were measured in feces from pregnant and nonpregnant sows by a direct ELISA without extraction. Highly significant differences in E1 concentrations were found in feces from nonpregnant and pregnant sows (P = 0.

Interrelation of fatty acid composition in adipose tissue, serum, and liver of dairy cows during the development of fatty liver postpartum.

We investigated the composition of fatty acids in adipose tissue, serum, and liver of cows that were fed at restricted energy intake or were overfed during the dry period. Overfed cows had higher concentrations of serum nonesterified fatty acids and consequently accumulated greater amounts of triacylglycerols in the liver than did cows that were fed at restricted energy intake. The percentages of the different fatty acids present in adipose tissue were similar for both groups and did not change during sampling intervals.

[Nutrition and fertility in agricultural domestic animals].

This paper deals with the reduction of fertility in cattle and pigs due to increased production. Special attention has been paid to the negative energy and protein balances during the first weeks post partum. It has been questioned which organs and organ systems become affected by the changes in these balances.

Relationship between overfeeding and overconditioning in the dry period and the problems of high producing dairy cows during the postparturient period.

In dairy cows, overfeeding during the dry period leads to overcondition at calving and to depression of appetite after calving. As a consequence, at calving overconditioned high-producing dairy cows inevitably go into a more severe negative energy balance (NEB) postpartum than cows that have a normal appetite. During the period of NEB, the energy requirements of the cow are satisfied by lipolysis and proteolysis.