Relationships between thyroid hormones and serum energy metabolites with different patterns of postpartum luteal activity in high-producing dairy cows

Prepartum supplementation of Ascophyllum nodosum meal or ethylenediamine dihydroiodide: Effects on colostrum yield and growth and health of dairy calves

We aimed to evaluate the effects of prepartum supplementation of different I sources (Ascophyllum nodosum [ASCO] meal and ethylenediamine dihydroiodide [EDDI]) on colostrum yield, blood concentrations of glucose, BHB, and thyroid hormones, and growth of dairy calves. Forty multiparous Holstein cows were blocked by lactation number and expected calving date and assigned to 1 of 4 treatments 28 d before parturition: (1) EDDI supplemented (11 mg/d) to a basal diet to meet the NRC (2001) I concentration of 0.5 mg of I/kg of DMI (control = CON [0 g/d of ASCO meal]; actual I concentration = 0.68 mg/kg of DMI); (2) CON plus 57 g/d of ASCO meal (low seaweed supplementation = LSW); (3) CON plus 113 g/d of ASCO meal (high seaweed supplementation = HSW); or (4) CON plus 151.3 mg/d of EDDI formulated to match the amount of I provided by HSW (high EDDI = HEDDI). Forty-one calves were blocked based on their dams' treatments and received 300 g of IgG via colostrum replacer immediately after birth. At 24 h after calving, calves were offered (DM basis) 676 g of milk replacer (25.3% CP, 16.5% fat) until d 49 and 338 g until weaning. Free-choice texturized starter (28.2% CP) and water were offered ad libitum from 24 h to 8 wk of life. Blood samples were collected for analyses of IgG (0 h and 24 h of age), thyroid hormones (d 14, 28, and 56 of age), and BHB (weekly). On d 5 of life, a xylose challenge was conducted by supplementing 0.5 g of d-xylose/kg of BW, with blood samples taken over a 12-h period. Weekly skeletal and BW measurements were also recorded. The concentration of colostral fat was greater in HSW than HEDDI cows, and it tended to increase linearly with ASCO meal supplementation. Although I intake increased linearly with feeding incremental amounts of ASCO meal to close-up cows, the transfer of I from feed to colostrum decreased quadratically. Neither I intake nor colostral I transfer efficiency changed when feeding HSW versus HEDDI. Calves born to HSW dams had a greater initial BW and final hip height, as well as tendencies for greater weekly hip height and final withers height compared with HEDDI calves. Calf BW gain tended to decrease linearly with ASCO meal supplementation. The 24-h apparent efficiency of absorption of IgG tended to increase in HSW versus HEDDI calves. Plasma glucose concentration on d 5 of life decreased linearly in response to incremental levels of ASCO meal. Furthermore, the plasma concentration of biweekly total thyroxin and whole-blood concentrations of weekly BHB and final BHB responded quadratically to ASCO meal, with the lowest values observed for LSW calves. In summary, prepartum supplementation with incremental amounts of ASCO meal to close-up cows did not change colostrum composition. However, feeding HSW versus HEDDI increased colostral fat concentration and initial BW in calves.

Technical Validation of Ultrasound Assessment of the Thyroid Gland in Cattle

Little is known about thyroid diseases in ruminants, probably due to the lack of diagnosis techniques developed in this species. However, thyroid ultrasound (TU) is widely used in human and in companion animal's medicine. It is a cheap and non-invasive examination, which allows for the identification of thyroid structures or diffuse diseases. The aim of this study was to evaluate the accuracy of TU in five calves and five cows through inter- and intra-observer repeatability. The size of the thyroid gland was measured from three views: left sagittal, right sagittal and transverse; nine measurements per view. The intra-observer coefficient was calculated for each observer. For the inter-observer, the first observer was a board-certified imagist (European College of Veterinary Diagnostic Imaging diplomate), the second was a board-certified specialist in bovine and herd management (European College of Bovine Health Managementdiplomate) and the third was an in-trained veterinarian for the TU. They each scanned the thyroid gland successively, following the same method. The intra-observer variabilities for observers 1, 2 and 3 were 8.22%, 5.53%, 5.38%, and 7.18%, 8.65% and 6.36%, respectively, for calves and cows. The inter-observer variability for calves was 10.4% and for cows, 11.8%. This study confirms the feasibility of repeatable intra- and inter-observer TU-estimated measurements in cattle.

Production, milk iodine, and nutrient utilization in Jersey cows supplemented with the brown seaweed Ascophyllum nodosum (kelp meal) during the grazing season

Kelp meal (KM) is a supplement made from the brown seaweed Ascophyllum nodosum, known to bioaccumulate iodine (I) and to be the richest source of phlorotannins, which can inhibit ruminal proteolysis and microbial growth. The objective of this study was to investigate the effects of KM on production, milk I, concentrations of blood metabolites, apparent total-tract digestibility of nutrients, and CH4 emissions in grazing dairy cows. Eight multiparous Jersey cows averaging (mean ± SD) 175 ± 60 d in milk and 12 primiparous Jersey cows averaging 142 ± 47 d in milk at the beginning of the study were assigned to either 0 g/d of KM (control diet, CTRL) or 113 g/d of KM (brown seaweed diet, BSW) in a randomized complete block design. Diets were formulated to yield a 70:30 forage-to-concentrate ratio and consisted of (dry matter basis): 48% cool-season perennial herbage and 52% partial TMR (pTMR). Each experimental period (n = 3) lasted 28 d, with data and sample collection taking place during the last 7 d of each period. Cows had approximately 16.5 h of access to pasture daily. Herbage dry matter intake increased, and total dry matter intake tended to increase in cows fed BSW versus the CTRL diet. Milk yield and concentrations and yields of milk components were not affected by diets. Similarly, blood concentrations of cortisol, glucose, fatty acids, and thyroxine did not change with feeding CTRL or BSW. However, a diet × period interaction was observed for milk I concentration; cows offered the BSW diet had greater milk I concentration during periods 1, 2, and 3, but the largest difference between BSW and CTRL was observed in period 2 (579 vs. 111 µg/L, respectively). Except for period 2, the concentration of milk I in cows fed KM did not exceed the 500 µg/L threshold recommended for human consumption. Diet × period interactions were also found for serum triiodothyronine concentration, total-tract digestibilities of crude protein and acid detergent fiber, CH4 production, and urinary excretion of purine derivatives. Overall, the lack of KM effects on milk yield and concentrations and yields of milk components indicate that dairy producers should consider costs before making KM supplementation decisions during the grazing season. Future research is needed to evaluate the concentration of I in retail organic milk because of the high prevalence of KM supplementation in northeastern and midwestern US organic dairies and possibly in other regions of the country.

Antioxidant levels, copper and zinc concentrations were associated with postpartum luteal activity, pregnancy loss and pregnancy status in Holstein dairy cows

The role of oxidative stress in the control of female reproduction has not been fully elucidated in ruminants; however, it seems that antioxidants can make influence to the reproductive axis at different levels. Therefore, the aim of this study was to determine the relationship between antioxidant status and concentrations of trace minerals (chromium (Cr), copper (Cu), iron (Fe), and zinc (Zn)) with postpartum luteal activity and fertility in Holstein dairy cows. The cows (n = 100, a parity range of 2-5, and a body condition score (BCS) of 3.0 ± 0.25, mean ± SEM) were assigned to the experiment at second week post calving. Ovarian follicular dynamics were monitored twice a week (from 3rd to 6th weeks post calving) by transrectal ultrasonography (US). Blood samples were collected twice weekly from the 3rd to the 6th weeks post calving at timed artificial insemination (TAI), and days 32 and 50 post AI to determine superoxide dismutase (SOD), glutathione peroxidase (GPX), total antioxidant capacity (TAC), and trace mineral concentrations. There were associations between plasma concentrations of SOD, GPX, and TAC with postpartum luteal activity (PLA, P = 0.01) and ovulation (P = 0.03). Mean plasma SOD and GPX activities and TAC levels (U/mL) were greater in cows with normal luteal activity (NLA) than prolonged luteal phase (PLP) and anovulation (AO) cows, as well as in ovulated compared to AO cows (P = 0.03). Pregnant cows had greater levels of SOD, GPX, and TAC (U/mL) at TAI than non-pregnant cows (P = 0.01). Plasma Cu and Zn concentrations increased in pregnant compared to non-pregnant cows at TAI. In conclusion, antioxidant levels and Cu and Zn concentrations were associated with PLA and fertility.

Postpartum hormone and energy profiles and their influence on the resumption of ovarian cyclicity in Curraleiro Pé-Duro cows

The objective of this study was to evaluate hormone and energy profiles in the postpartum period and to correlate these profiles with the resumption of ovarian cyclicity, as well as characterizing the postpartum short estrous cycle of Curraleiro Pé-Duro cows. Twelve Curraleiro Pé-Duro cows were examined via rectal palpation and ultrasound at 10 days postpartum, and subsequently examined daily to evaluate the resumption of ovarian cyclicity as well as every five days in order to evaluate uterine involution. Upon analysis of the data, it was possible to observe the formation of two distinct groups, one of which was comprised of those animals which returned to cyclicity within 60 days postpartum and another comprised of those animals which returned to cyclicity more than 105 days postpartum. Therefore, animals were divided into two groups; precocious, designated Ov Group, and delayed, designated NOv Group, wherein the cut-off time for all tests was 60 days postpartum. Statistically significant differences (P < 0.01) between the groups occurred only regarding the day of 1st ovulation, which in the Ov Group averaged 51.4 ± 9.3 days and in the NOv Group averaged 138.3 ± 19.8 days postpartum. The other postpartum short estrous cycle variables assessed did not show statistically significant differences (P > 0.05) between the groups. NEFA, BHBA and thyroxine concentration levels did not differ (P > 0.05) between the groups in any of the statistical analyses. However, in the analysis comparing growth curves, triglycerides levels were higher for the Ov Group (P = 0.04) and cholesterol levels were higher for the NOv Group (P = 0.02). In this experiment, a small influence of a negative energy balance between the groups was observed, suggesting that these animals can present significant genetic variability due to natural selection, as evidenced by the formation of groups of animals with precocious and delayed reproductive characteristics.

Short communication: Iodine concentrations in serum, milk, and tears after feeding Ascophyllum nodosum to dairy cows-A pilot study

Kelp (Ascophyllum nodosum) is rich in iodine and often fed by organic dairy producers as a mineral supplement to support animal health. A commonly held belief is that kelp supplementation decreases susceptibility to infectious bovine keratoconjunctivitis due to increased iodine concentrations in tears. Whereas serum and milk iodine concentrations are positively correlated and modulated by oral iodine supplementation, nothing is known about the iodine concentration of tears. Therefore, the 3 objectives of this pilot study were to determine (1) the iodine content of tears, milk, and serum of cows after being fed kelp for 30d; (2) the trace mineral and thyroid status of cows before (d 0) and after being fed kelp for 30d; and (3) the in vitro growth rate of bacteria in tears (Moraxella bovis) or milk (Staphylococcus aureus, Escherichia coli, Streptococcus uberis) collected from cows fed no kelp (d 0) or kelp (d 30). Cows (n=3/treatment) were individually fed 56g of kelp per day (n=3/treatment) or not (n=3/no treatment) for 30 d. Daily feed intake of the TMR was recorded and weekly TMR, kelp, milk, blood and tear samples were collected and analyzed for iodine. The feed samples were pooled and further analyzed for other minerals. On d 0 and 30, liver biopsies and blood samples were collected and analyzed for mineral content and thyroid hormone concentrations, respectively. An inhibition test used milk and tear-soaked plates from kelp-fed cows (d 0 and 30) as well as 1 and 7.5% iodine as positive and distilled water as negative control. As expected, serum iodine concentrations were positively correlated with milk and tear iodine concentrations. Whereas the iodine concentrations in serum increased significantly in the kelp-fed cows during the 30-d study, milk and tear iodine concentrations increased only numerically in these cows compared with the control group. Liver mineral profiles were comparable between groups and generally did not change over the course of the study. Thyroid hormones remained overall within the reference range throughout the trial. Neither milk nor tears from kelp-fed cows inhibited in vitro growth of any of the plated bacteria. In summary, serum iodine concentration was correlated with the iodine concentration in milk and tears and feeding kelp increased only the serum iodine levels of cows in this trial. Bacterial growth was not inhibited in milk and tears of kelp-fed cattle in vitro, and prevention of infectious bovine keratoconjunctivitis would not be based solely on increased iodine concentrations in tears.

The relationship between serum adiponectin and postpartum luteal activity in high-producing dairy cows

The aims of the present study were to initially determine the pattern of serum adiponectin concentrations during a normal estrous cycle in high-producing postpartum dairy cows and then evaluate the relationship between the serum concentrations of adiponectin and insulin with the commencement of postpartum luteal activity and ovarian activities in clinically healthy high-producing Holstein dairy cows. During a normal estrous cycle of cows (n = 6), serum adiponectin concentrations gradually decreased (P < 0.05) after ovulation by Day-17 estrous cycle and then increased before the next ovulation. Cows with higher peak of milk yield had lower serum adiponectin concentrations by week 7 postpartum (P = 0.01). Serum adiponectin and insulin concentrations in cows with different postpartum luteal activity (based on the progesterone profile) were evaluated using the following class of cows: normal (≤45 days, n = 11) and delayed (>45 days, n = 11) commencement of luteal activity (C-LA) and four different profiles of normal luteal activity (NLA, n = 5), prolonged luteal phase (n = 6), delayed first ovulation (n = 6), and anovulation (AOV, n = 5). Serum adiponectin concentrations decreased gradually by week 3 postpartum in NLA and then increased; whereas in AOV and delayed first ovulation, they were decreased after week 3 postpartum (P < 0.05). Moreover, serum adiponectin concentrations in NLA were more than AOV at weeks 5 and 7 postpartum (P = 0.05). The increase in the milk yield from weeks 1 to 7 postpartum in prolonged luteal phase (P = 0.05) and AOV (P = 0.04) cows was more than that of NLA cows. Insulin concentrations were almost maintained at a stable level in NLA cows (P > 0.05), whereas they increased in the other groups (P < 0.05). Moreover, adiponectin concentrations in cows with C-LA greater than 45 days decreased more than those with C-LA 45 days or less after week 3 postpartum (P = 0.002). Serum adiponectin concentrations at week 7 postpartum were lower in delayed C-LA (P = 0.01). Milk yield in cows with C-LA greater than 45 days increased more than cows with C-LA 45 days or less postpartum (P = 0.002). Insulin concentrations increased relatively in parallel from weeks 1 to 7 postpartum in cows either with C-LA greater than 45 or with C-LA 45 days or less. We showed for the first time the profile of serum adiponectin concentrations in a normal estrous cycle of dairy cows, and furthermore, it was found that high-producing dairy cows with higher postpartum serum adiponectin concentrations had NLA and earlier C-LA.

Hyperplastic goiter in two adult dairy cows

Iodine excess and resultant hyperplastic goiter are well documented in neonatal ruminants, but little is reported on iodine excess in adult ruminants and associated histological changes of the thyroid gland. Two adult Holstein cows from a Michigan dairy herd that had lost several other animals had nonspecific clinical signs of illness and were submitted for necropsy. Thyroid glands of one of these 2 animals were grossly and markedly enlarged, and histologically, thyroid glands from both animals had regions of cystic nodular hyperplasia and follicular atrophy. Thyroid glands from both animals had markedly elevated iodine concentrations. Investigation into the potential source of excessive iodine on the farm revealed multiple sources of supplemental dietary iodine and probable uneven feed and mineral mixing. Based on the findings of this investigation, adult cattle could be susceptible to excessive doses of iodine. Possibility of previous iodine deficiency before supplementation period, with subsequent development and persistence of thyroid hyperplasia and cystic change, cannot be completely excluded. Current findings suggested that iodine excess in adult cattle can result in nodular hyperplastic goiter. Use of iodized salt in mineral supplements in adult dairy herds is common practice, and accidental excessive iodine supplement may be more common than reported. Recognizing gross and histological thyroid gland changes, consisting of concurrent cystic follicular hyperplasia, atrophy, and fibrosis should raise suspicion of iodine excess and/or prior deficiency in a cattle herd, and ancillary tests such as serum iodine measurements should be part of the diagnostic workup in suspected cases.