Is prolonged luteal phase a problem in lactating Holstein cows?

In this study, the main objective was to assess if long luteal phases could have other causes than pregnancy losses. We enrolled Holstein dairy cows ≥50 d in milk (DIM) from a commercial herd in Brazil from October 2016 to August 2017. All cows received an estradiol-based synchronization protocol, and, on the day of insemination (d 0), were randomly assigned either an artificial insemination (AI) or a placebo insemination (PBO) in a 3:1 ratio. An ultrasound was used to assess the presence of a CL on d17, 24, and 31, which, combined to the information from patches for the detection of estrus, was used to determine the length of the luteal phase following AI or PBO. Pregnancy was assessed by ultrasound on d 31 and cows that were pregnant were excluded from the analyses. The length of the estrous cycles was categorized as short (<17 d), normal (17-23 d), long (24-30 d), and very long (≥31 d). We compared the proportion of cows in each category between the AI and PBO groups using a cumulative ordinal mixed model. We define prolonged luteal phase as estrous cycles ≥24 d and tested its association with potential risk factors (parity, season, DIM, uterine size and position score, milk production, body condition score, and the presence of a corpus luteum (CL) at enrollment to the synchronization protocol) using mixed logistic regression models. Results are presented as odds ratio (OR) and 95% credible intervals (BCI). Data from 876 inseminations (AI: n = 616, PBO: n = 260) was collected. Overall, 12% of estrous cycles were short, 31% were normal, 19% were long, and 38% were very long. There was no difference in the odds of being in longer estrous cycle categories for the AI compared with the PBO group (OR = 0.92, 95% BCI = 0.76-1.10). Season and presence of a CL at enrollment were associated with prolonged luteal phase. In the AI group, there was a possible effect of early pregnancy losses on the lifespan of the CL, but not the PBO group, which led us to conclude that long and very long estrous cycles were not all caused by the embryonic loss. In fact, the high prevalence of cows with an extended CL lifespan in the present study suggests this could be an under- or miss-reported characteristic of high-producing lactating Holstein cows. This finding may have important repercussions in the understanding of the CL function physiology of lactating Holstein cows.

Supplementation of prepartum dairy cows with ß-carotene.

The prepartum supplementation of dairy cows with ß-carotene was evaluated. Cows were blocked by parity and expected calving date and assigned to a treatment: ß-carotene (1.2 g/cow per d) or control (no supplementation). The same total mixed ration batch was offered to all cows, and ß-carotene was top dressed to individual cows once per day. The data set contained 283 Holsteins that received a treatment for >14 d (29.1±6.9 d). Frequency distributions were analyzed with the GENMOD procedure of SAS using logistic regression for binomial data. Continuous variables were analyzed with the MIXED procedure of SAS. Within parity, nonparametric estimates of the survivor function for reproductive variables were computed using the product-limit method of the Kaplan-Meier method with the LIFETEST procedure of SAS. Plasma ß-carotene concentration before supplementation was similar between supplemented and nonsupplemented cows (2.99µg/mL) and peaked at 3.26±0.175µg/mL on d -15±2.4 precalving for supplemented cows (2.62±0.168µg/mL for control). Colostrum density, milk yield, and milk composition were similar between treatments. ß-Carotene tended to increase milk protein content from 2.90 to 2.96% and to decrease the proportion of primiparous cows with a milk fat to protein ratio >1.5 from 22.6 to 6.4%. The proportion of primiparous and multiparous cows with difficult calving, metritis, progesterone >1 ng/mL at 21 d and at 42 d in lactation, % conception at first service, and % pregnancy at 90 and 150 d in lactation were similar between treatments. A trend for decreased incidence of somatic cell count >200,000 cells/mL was present in multiparous cows supplemented with ß-carotene (38.9% vs. 28.1%). ß-Carotene was associated with a reduction in the proportion of multiparous cows with retained placenta 12 h postpartum from 29.9 to 21.7%; time of placenta release was 392 min (340 to 440) for ß-carotene and 490 min (395 to 540) for control (median and 95% confidence interval). For primiparous cows, placenta release was not affected by ß-carotene (incidence was 15.4%). The intervals from calving to first estrus, to first service, and to conception were not affected by ß-carotene supplementation in either parity. However, independent of treatment, cows with improved reproductive efficiency had increased postpartum ß-carotene concentration in plasma. The prepartum supplementation of ß-carotene increased plasma concentration around calving. No response in milk yield or reproductive performance was detected. Beta-carotene supplementation was associated with a lower incidence of retained placenta in multiparous cows.

High-fat diet increases thyrotropin and oxygen consumption without altering circulating 3,5,3'-triiodothyronine (T3) and thyroxine in rats: the role of iodothyronine deiodinases, reverse T3 production, and whole-body fat oxidation.

This study investigated the effects of obesity induced by high-fat (HF) diet on thyroid function and whole-body energy balance. To accomplish that, we assessed the effects of 8 wk of HF diet on several parameters of hypothalamus-pituitary-thyroid axis function. Serum total T(4) and T(3), rT(3), and TSH, the activity of type 1 and type 2 deiodinases in central and peripheral tissues were determined. Also, we measured in vivo energy balance, substrate partitioning, and markers of leptin resistance. Here we provide novel evidence that prolonged positive energy balance acquired by feeding a HF diet induced hyperactivation of the hypothalamus-pituitary-thyroid axis, which was characterized by 2.24-, 1.6-, and 3.7-fold elevations in hypothalamic TRH expression, thyroid iodide uptake, and serum TSH, respectively. Serum T(4) and T(3) were normal together with augmented deiodinase type 1 activity in liver (1.3-fold) and kidney (1.2-fold) and increased (1.5-fold) serum rT3 in HF rats. Despite no increase in circulating levels of T(3) and T(4), whole-body oxygen consumption was increased, and substrate metabolism was shifted toward fat oxidation in HF rats. These in vivo metabolic adjustments were mainly driven by the fat content of the diet. Furthermore, spontaneous dark cycle physical activity was reduced by 30% in rats fed a HF diet, which limited energy expenditure and favored the development of obesity. Our findings provide new insight into the endocrine and physiological mechanisms that underlie the alterations in thyroid hormone availability, energy balance, and metabolic partitioning in HF diet-induced obesity.

Tissue-specific deiodinase regulation during food restriction and low replacement dose of leptin in rats.

The relationship between thyroid function and leptin has been extensively studied; however, the mechanisms underlying the changes in thyroid hormone economy that occur during caloric deprivation remain elusive. Our goal was to evaluate the thyroid function of rats submitted to 40% food restriction after chronic leptin replacement. Caloric restriction for 25 days led to significantly reduced serum leptin, thyroid-stimulating hormone (TSH), thyroxine (T(4)), and triiodothyronine (T(3)) and increased serum corticosterone, while liver, kidney, and thyroid type I deiodinase (D1) and brown adipose tissue (BAT) type II deiodinase (D2) activities were decreased and hypothalamic D2 was significantly increased. Interestingly, thyroid iodide uptake was unchanged by caloric restriction, but thyroperoxidase (TPO) activity was significantly reduced. Leptin replacement for the last 10 days of caloric restriction normalized serum leptin and TSH levels, but serum T(4) and T(3) levels and thyroid D1 and TPO activities were not reestablished. Also, a negative effect of leptin administration on Na(+)-I(-) symporter function was detected. Liver and kidney D1 and hypothalamic and BAT D2 were normalized by leptin, while pituitary D2 was significantly decreased. In conclusion, a tissue-specific modulation of deiodinases might be implicated in the normalization of thyroid function during leptin replacement in food-restricted rats. Although leptin restores the hypothalamus-pituitary axis during food restriction, it exerts a direct negative effect on the thyroid gland; thus normalization of serum thyroid hormones might depend on changes in deiodinase activities and the long-term thyroid stimulation by TSH to counterbalance the direct negative effects of leptin on the thyroid gland.

Effects of fish oil on the central nervous system: a new potential antidepressant?

In the last 100 years major depression has increased worldwide. In this study we provided coconut fat (CF, rich in saturated fatty acids) or fish oil (FO, rich in n-3 polyunsaturated fatty acids) to female rats throughout pregnancy and lactation and then to their offspring post-weaning and examined lipid brain profile and the possible effect of FO as antidepressant agent in the offspring in adulthood (F1). Rats were submitted to forced swimming test, elevated plus maze, Morris water maze and open field. Peroxidation rate in the cerebral cortex and hippocampus were measured. Docosahexaenoic acid (DHA) concentration in dam's milk, eicosapentaenoic acid (EPA) and DHA concentration in hippocampus and cerebral cortex from F1 rats FO supplemented increased significantly when compared to control (C) and CF rats. Arachidonic acid/EPA ratio in the cerebral cortex and hippocampus decreased in rats submitted to forced swimming test. Peroxidation rate were not different between the groups. Immobility time in the forced swimming test in FO group was reduced (p < 0.01) when compared to C and CF rats. We conclude that lifelong intake of FO was able to induce an antidepressant effect with EPA and DHA concentration increased in the cerebral cortex and hippocampus.

Evaluation of a program to overcome vitamin A and iron deficiencies in areas of poverty in Minas Gerais, Brazil.

Randon samples of children from both sexes from Belo Horizonte, the capital City, and from Turmalina, Jequitinhonha Valley, Minas Gerais, Brazil, were submitted to nutritional evaluation before and after the intervention "Program to Overcome Vitamin A and Iron Deficiencies in Areas of Poverty in Minas Gerais, Brazil". After the first examination, all the children received, with an interval of 180 days, a single oral dose of vitamin A, oral iron sulfate during 50 days, and 200 mg of Mebendazol/day for three days. Thirty days after ending administration of the third dose of medicine, the children were subjected to a new evaluation. In Belo Horizonte, the first evaluation revealed a high prevalence of deficient and low values of vitamin A in preschool children (21.5%) and school children (21.7%). A small prevalence of low hematocrit values was also observed in both groups. Deficient and low values of hemoglobin were found as well in 21.5% of preschool children and in 17.5% of school children. The second evaluation, practiced 30 days after the third dose of medicine, showed a small incidence of low vitamin A values (4.3% in preschool children and 2.9% in school children) and low hemoglobin values (6.5% in preschool children and 2.9% in school children). No deficient values of hemoglobin and vitamin A were observed. Concerning the hematocrit value, only one school child presented a low value at the second evaluation. On the other hand, in Jequitinhonha Valley, five cases of Bitot spot with conjunctival xerosis, two cases of corneal xerosis, and one case of keratomalacia were detected at the first examination. Thirty days after ending the third dose of medicine, only one corneal scar was observed. Only a small number of children with deficient and low levels of vitamin A and hemoglobin was found in the final evaluation (less than 8%), while this number was high at the first evaluation (above 38 and 12%, respectively). These results show the efficiency of the intervention Program in relation to hypovitaminosis A and iron anemia prevention. The Program is now being implemented by the Brazilian Ministry of Health.

[Diagnosis of hypovitaminosis A and nutritional anemia status in the population of Vale do Jequitinhonha, Minas Gerais, Brazil]. / Diagnóstico da situação da hipovitaminose A e da anemia nutricional na população do Vale do Jequitinhonha, Minas Gerais, Brasil.

A survey was carried out with the purpose of evaluating the nutritional status of the population of Jequitinhonha Valley in regard to vitamin A deficiency and iron-deficiency anemia. A Program--"Programa de Combate à Hipovitaminose A e à Anemia Nutricional Ferropriva em Bolsões de Probreza de Minas Gerais"--is being implanted by the Instituto Nacional de Alimentacão e Nutriçao (INAN) aiming to the prevention of such deficiencies. A random sample of 2,357 children from the towns: Turmalina, Minas Novas and Capelinha (Vale do Jequitinhonha), Minas Gerais (1,604 living in the urban and 753 in the rural areas) was submitted to an eye examination. Blood was drawn from a random subsample of these children (157 from the urban area and 107 from the rural area), in oder to detect possible nutritional problems. The following results were observed (preschool and school children, respectively): 1. Hemoglobin: 23.9% and 20% of the population in the urban area, 34.6 and 18.2% in the rural area, had low and deficient values, respectively. 2. Hematocrit: 1.5 and 2.2% of the population in the urban area, 17.3 and 5.5% in the rural area, had low values. 3. Vitamin A: 8.9 and 4.4% of the population in the urban area, 5.8 and 0% in the rural area, had deficient values (less than 10 micrograms/dl); 26.9 and 31.1% in the urban area, 26.9 and 23.6% in the rural area, had low values (10-20 micrograms/dl). These results show the occurrence of nutritional anemia and vitamin A deficiency in the observed children. As to the eye examination this was performed in 2,357 children. A high incidence of conjunctival xerosis (3.16 and 6.04% in the urban area, 7.7 and 12.6% in the rural area, in preschool and school children, respectively), was detected. Five cases of conjunctival xerosis with Bitot spot (0.2%), corneal xerosis (0.08%) and kerotomalacia (0.04%) were observed. The therapeutic effect of 200,000 UI of oral vitamin A was more efficient in preschool children (90.3% of positive reactions) than in school children (25.9% of positive reactions). The causes of the different reactions are now under study.

Potentiation of bradykinin action on smooth muscle by a scorpion venom extract.

Gel filtration of the water extract of the venom of the scorpion T. serrulatus showed four peaks; the first peak (P1) is devoid of toxic activity but increases the bradykinin-induced contraction of isolated rat uterus and guinea-pig ileum. The stepwise fractionation of the pooled P1 peak was performed in a DEAE-cellulose column and the bradykinin potentiating activity was found in the second protein peak. Finger-printing of this material showed that the bradykinin potentiating material migrates to the anode, giving two spots when submitted to chromatography, the activity being found in the spot that presents the greatest Rf. The potentiator is destroyed by heating at 97 degrees C, is not dialysable and is destroyed by incubation with pronase. Some of these properties differentiate it from the BPF's from snake venoms.

Histo-physiological study of hypophysectomized dogs in which the hypophysis was replaced by parotid gland.

This work is an attempt to repeat and confirm the results published by Alvarez-Buylla et al., concerning to hypophysectomy and transplant in salivary gland in dogs. It was found that the survival time was longer in the hypophysectomized-transplanted animals than in those merely hypophysectomized. The 131I uptake by the thyroid of transplanted dogs was lower than by normal dogs, but higher than by the hypophysectomized ones. The histological examination of the hypothalamic-hypophyseal region in both groups of operated animals showed remnants of pars tuberalis cells. The graft of the parotid gland became vascularized exhibiting dilated tubules containing PAS positive granules. An atrophy of thyroid and adrenal glands was also observed. Primordial follicles, follicles in development and cell cords could be found in the ovary of all transplanted animals; in some dogs corpus luteum could also be observed. These results suggest that the transplanted gland in some way provides conditions for the remnant of the hypophyseal cells to perform their function.