Plasma levels of testosterone (T), 17-β-estradiol (E2), progesterone (P4), dehydroepiandrosterone (DHEA), corticosterone (B), thyroxine (T4) and triiodothyronine (T3) were monitored during postnuptial and the prenuptial molt in domestic goose (Anser anser domesticus) in both sexes. 1. At the beginning of postnuptial molt (when the old, worn dawny-, and cover feathers’ loss starts) in ganders, the levels of T, E2, P4 decrease while DHEA and B significantly increase. The elevated levels of T4 and low T3 concentrations characteristic of the last phase of the reproduction, remain unchanged. In layers, similar changes were observed, however, B decreases. 2. In the early phase of outgrowth of wing and cover feathers, plasma levels of T, E2 and P4 are low. Elevated B, DHEA and T4 concentrations decrease in ganders, while in layers DHEA increases and B and T4 levels remain unchanged. T3 increases in both sexes. 3. The subsequent intensive outgrowth period of wing- and cover feathers both in ganders and in layers is characterized by very low levels of T, E2, DHEA and T4, but P4 increased, and T3 concentration remain high. 4. At the end of postnuptial molt — when the outgrowth of dawny, cover-, and wing feathers stops — very low T, E2, P4, DHEA and T4 levels and and high T3 plasma levels were found in both sexes. Fast increase of plasma B was detected in ganders, while in geese, B concentration remain high. 5. During prenuptial molting (outgrowth of contour and tail feathers) low E2, P4 and T4, increasing T and DHEA, but very high T3 and B plasma concentration were measured in ganders. In layers, very low T, E2, P4, DHEA and T4 levels, and very high B and T3 levels were found. 6. At the beginning of the fall-winter sexual repose (postmolting stage) T, E2, P4, DHEA and T4 levels increase, T3 and B declines in both sexes. 7. In the subsequent phase of fall-winter period (preparatory stage) there is a further increase in T, P4 and T4, a fast increase of B and a decrease of E2, DHEA and T3 in ganders. In layers, T, P4 and DHEA decrease, B increases and the T4 and T3 do not change. 8. At the beginning of reproduction high T level, unchanged DHEA, slightly declined P4, and decreased E2, T4, T3 and a strong decline of B concentrations occur in ganders. In layers, T is further increased, E2 and P4 shows high levels, and, at the same time DHEA and T3 remain unchanged, while B and T4 decrease.
Changes of progesterone (P4) profiles and oestrous cycle were investigated up to 70 days in 20 superovulated Holstein-Friesian cows in a dry tropical environment (Brazil). Superovulated cows showed no significant differences in relation to P4 level at the time of embryo recovery (39.0 ± 27.1 nmol/L, P = 0.536), first and second (12.0 ± 6.0 and 10.7 ± 2.2 nmol/L, P = 0.543) cycle. There was a close correlation between serum P4 concentration and the number of corpora lutea (CL; 13.3 ± 9.5) at the recovery (P < 0.0001). After the embryo collection, cows returned to cycle in different ways: (i) group of donors returning to cycle after 2.2 ± 0.8 days, (ii) group with a delay of 11.0 ± 1.9 days; and (iii) animals having a long (28.8 ± 2.2 days) acyclic period, which is significant (P < 0.001). The remaining animals (30%) showed cystic ovarian malformations. P4 level at the time of embryo recovery does not influence the oestrous cycle changes. The results suggest that Holstein-Friesian donor cows may suffer from cystic ovarian degeneration and may have a long acyclic period after superovulatory treatment in a tropical climate.
Leptin and leptin receptor were studied in the mammary gland of non-pregnant dry and lactating cows. Using RT-PCR it was demonstrated that leptin and its short (Ob-Ra) and long (Ob-Rb) receptor isoforms are expressed both in the dry and the lactating mammary gland tissue. Tissue distribution of leptin and its receptor mRNA transcripts were examined by insitu hybridisation, while the leptin protein was localised by immunohistochemistry. Although in situ hybridisation is semiquantitative, our morphological data suggest that the epithelial leptin mRNA expression of the lactating gland is higher than that of the dry gland. To compare the leptin mRNA levels between dry and lactating udders competitive PCR was used, which showed no difference in leptin expression for the whole mammary tissues. The lack of difference in total leptin mRNA levels is explained by the high adipose tissue content of the dry mammary gland. Leptin and its receptor transcripts are expressed mainly in the epithelial cells of lactating cows, while in dry mammary tissue the signal is found in the stromal tissues as well. The results provide additional evidence that locally produced leptin takes part in the regulation and maintenance of mammary epithelial cell activity.
The heart rate variability (HRV) parameters of dairy cows were monitored during parlour (PARL) and the later installed automatic (AMS) milking on a small-scale commercial dairy farm in Hungary. The aim of the study was to assess stress in relation to the type of milking and the frequency of human interaction. Parlour milking involved regular moving and crowding of the animals with frequent human interaction, which were much less frequent in automatic milking. The first phase of the study was conducted prior to the changeover [n = 27] and the second two months afterwards [n = 19 (of the cows from the first phase)]. Heart rate (HR) was recorded by the Polar RS800 CX recording system. HRV parameters indicative of sympathovagal balance were calculated for periods of lying and standing in the barn, waiting before milking and milking, respectively. Morning and evening faecal glucocorticoid concentrations were also measured. Fear of humans was tested by an avoidance distance test. Baseline HRV parameters showed no difference (P > 0.05) between the two systems. In the periods before, during and after milking a higher sympathetic tone was detected in cows in the PARL phase. Mean faecal glucocorticoid concentrations were higher at the time of parlour milking. The avoidance distance did not differ between the two phases. The results suggest that automatic milking might be less stressful for cows than parlour milking, possibly due to the shorter duration of restraint after milking and the less frequent human interaction.
The basic patterns of thyroid hormones [thyroxine (T4) and 3,3',5-triiodothyronine (T3)] and the T4 and T3 responses induced by thyrotropin releasing hormone (TRH) are reported in captive female barn owls (Tyto alba) during the non-breeding period. The main findings of the study, conducted on a total of 10 owls, are as follow: (1) The thyroid gland of barn owl can be stimulated by the classical TRH stimulation test. (2) T3 response was much more pronounced both under cold (around 10°C) and warm (around 20°C) conditions, whereas T4 response ranged so widely that we could not point out any significant change in it. (3) Basal T3 plasma level was significantly (p = 0.036) higher in birds exposed to cold temperature, and they responded to TRH treatment with a lower plasma T3 elevation than the birds kept in a warm chamber. This pattern, however, cannot be explained by increased food intake, but is in agreement with the fact that enhanced T3 level may account for higher avUCP mRNA expression, which results in higher heat production on the cell level. From the results it is concluded that altering T3 plasma level plays a significant role in cold-induced thermoregulation.
The aim of this study was to identify relationships among seasonal differences of fertility, metabolic parameters and appearance of irregular luteal forms in high-yielding dairy cows. Holstein-Friesian cows were put on the Provsynch regimen in winter (n = 10) and in summer (n = 10). Blood sampling (starting 35 days post partum) and rectal ultrasound examinations (starting post insemination) were carried out once a week in each examination period. Metabolic [plasma nonesterified fatty acid (NEFA) and beta-hydroxybutyrate (BHB) levels, ferric reducing ability of plasma (FRAP) and serum beta-carotene] and endocrine parameters [plasma thyroxine (T4), triiodothyronine (T3), insulin-like growth factor (IGF-I) and insulin levels] were measured. In summer, two cows were excluded from the study because of metritis and none of the remaining animals became pregnant, but 6 of the 8 cows had irregular luteal forms (ILF) on their ovaries. In winter, one cow was excluded because of metritis and 6 of the 9 cows became pregnant, while 2 of the 3 open cows had irregular luteal forms. In summer the mean plasma NEFA and BHB concentrations were significantly higher, while serum carotene and plasma IGF-I concentrations were significantly lower than in winter. The high plasma NEFA concentration found in summer seemed to be in association with the lower body condition score (BCS) caused by depressed appetite. In conclusion, statistical analysis supports the hypothesis that increased plasma NEFA and BHB and decreased plasma IGF-I concentrations may result in reduced fertility in summer. These changes may be associated with the more frequent appearance of ILFs and probably have a negative effect on ovarian function and/or oocyte quality.
Metabolic hormones [insulin, leptin, insulin-like growth factor-I (IGF-I), thyroxine (T4) and triiodothyronine (T3)], progesterone (P4) and beta-hydroxybutyrate (BHB) serum concentrations were evaluated and their effect on the superovulation results of donor cows was investigated in a semi-arid environment. Body weight, body condition score (BCS) and lactation stage were also included in the analysis. Twenty-three Holstein-Friesian cows were superovulated with 600 IU FSHp following the routine procedure and flushed on day 7 in a Multiple Ovulation and Embryo Transfer Centre in the semi-arid area of Brazil. The corpora lutea (CL) were counted and blood samples were collected for assays. All of the hormones investigated and BHB serum concentrations were within the physiological ranges. There was a positive correlation between hormones, except between BHB and all the others. The leptin level was influenced by feeding status, as indicated by the BCS. Insulin, T4, T3 and BHB levels were affected by milking status. Dry cows had higher levels of all hormones except BHB. An optimum level of leptin resulted in the highest number of CL, while the linear increase of P4, T4 and IGF significantly increased the number of CL.
Artificial insemination (AI) can undoubtedly be regarded as the oldest and most widely used assisted reproductive technique/technology (ART) applied in livestock production and it is one of the most important ARTs. The three cornerstones of its application are that it is simple, economical and successful. Artificial insemination offers many well-known benefits for producers. Fresh, fresh + diluted + chilled and frozen semen can be used for AI in small ruminants. To ensure its successful use, the AI technique must be selected on the basis of the type of semen planned to be used. This review paper gives a detailed overview of semen processing and its effects on semen quality, as well as of the AI techniques applied in small ruminants and their success rates.
A study was conducted to examine the effects of different oils on the plasma corticosterone concentrations of broiler chickens fed ad libitum or deprived of feed for 24 hours. A total of 36 Ross broilers were randomly assigned to one of three dietary treatments at 10 days of age and fed a grower diet supplemented with 60 g/kg soybean oil (rich in linoleic acid, C18:2n–6), linseed oil (rich in a-linolenic acid, C18:3n–3) or fish oil (rich in C14:0, C16:0, C16:1n–7, C20:1n–9; eicosapentaenoic acid and docosahexaenoic acid, EPA, C20:5n–3 and DHA, C22:6n–3), respectively, for 18 days. Dietary supplementation of fish oil resulted in lower (P < 0.05) baseline plasma corticosterone levels of chickens fed ad libitum for 18 days compared to soybean and linseed oil supplementations. Feed deprivation for 24 h induced a significant (P < 0.05) increase in corticosterone concentration in every treatment group compared to the ad libitum-fed birds. The hormone levels of feed-deprived birds did not differ significantly among groups fed diets supplemented with different oils.