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Serum concentrations of prolactin (PRL), insulin‐like growth factor‐1 (IGF‐1) and 25 hydroxyvitamin D3 (25‐OHD3) were analysed to investigate their possible involvement in the pathogenesis of benign prostatic hyperplasia (BPH). For this, dogs of the Rhodesian Ridgeback (RR) breed were used because of a verified breed disposition for the development of BPH. Labrador Retrievers (LR) served as controls. The prostate gland status was characterised by the prostate gland volume, clinical signs of BPH (haemospermia and sonographic findings) and the plasma concentration of canine prostate‐specific arginine esterase (CPSE). Breed specificity in the RR was expressed by a correlation of PRL with breed (p < 0.05). Similar relationships existed in the dogs with normal CPSE (CPSEn) with respect to the IGF‐1 concentrations (LR: p < 0.05). The latter were negatively correlated with prostatic volume and age (both p < 0.05). Concentrations of 25‐OHD3 were tendentially (p = 0.18) lower in the RR with increased CPSE (CPSEi) compared with the CPSEn LR and RR showing clinical signs of BPH. A negative correlation between serum 25‐OHD3 and age (p < 0.05) existed in the CPSEi RR. Proof of 25‐OHD3 in prostatic secretion proved to be a breed specific feature in the RR (p < 0.0001). For all RR dogs showing clinical signs of BPH, a close to significant (p = 0.06) positive correlation with prostate gland volume was found. The results of the present study reveal no clear hints towards the significance of PRL and IGF‐1 in the pathogenesis of canine BPH. In the RR breed there were indications of a causal relationship with age‐dependent changes in the vitamin D metabolism. The data suggest the possibility of preventing or treating canine BPH by administering vitamin D or substances involved in the intraprostatic vitamin D metabolism. [ABSTRACT FROM AUTHOR]

Homeostasis of calcium (Ca) and phosphate (Pi) is maintained by a concerted interplay of absorption and reabsorption via the gastrointestinal tract and the kidney and by storage and mobilization from the bone regulated mainly by parathyroid hormone (PTH), 1,25‐dihydroxycholecalciferol and calcitonin. The present study aimed at characterizing the effects of dietary P restriction on bone, vitamin D metabolism and rumen fermentation traits reflecting the endogenous P cycle maintaining the ruminal P supply for microbial metabolism. The experiments were done in eleven female, non‐pregnant, non‐lactating four‐ to nine‐year‐old Black Headed Mutton sheep allotted to two feeding groups: "P‐restricted" (0.11% P/kg DM and 0.88% Ca/kg DM) and "Control" (0.38% P/kg DM and 0.88% Ca/kg DM). Dietary P restriction did not lead to hypophosphataemia, probably due to a compensation by bone mobilization, demonstrated by increased serum concentrations of a resorption marker and altered gene expression in bone tissue. In addition, the RNA expression of fibroblast growth factor 23, a bone‐derived factor involved in the regulation of vitamin D metabolism, was significantly reduced with dietary P restriction. Furthermore, several genes related to vitamin D metabolism and plasma concentrations of 1,25‐(OH)2D were associated with serum concentrations of phosphate (Pi). In the parotid gland, the expression of the Pi transporter NaPi2b was negatively associated with serum Pi and positively with parathyroid PTH expression. Although Pi concentrations in saliva and the gastrointestinal tract were significantly reduced, we found no adverse effects of the P‐restricted ration on the production of short chain fatty acids, but slight differences in the production of butyrate as well as its relationship to rumen Pi and ammonia concentrations that might indicate an impact on ruminal fermentation. [ABSTRACT FROM AUTHOR]

This study investigated the effects of low potassium diets with different levels of Ca compared to two diets low in dietary cation–anion difference (DCAD) fed prepartum as a strategy to prevent hypocalcemia on sorting behaviour, total tract digestibility, oxidative status and energy and protein metabolism of transition cows. Forty‐eight pregnant dairy cows were assigned to 4 treatment groups: Low Ca, low K (LCLK), High Ca, low K (HCLK), Supplementation with anionic mineral mixture (AMS) supplementation with SoyChlor (CAS). After parturition, all animals were fed a standard postpartum diet. Data were collected until 21 DIM. Prepartum urinary pH was significantly reduced by the low DCAD diets, while postpartum Ca homeostasis was affected by the HCLK ration. Feeding AMS induced sorting against particles <1.18 mm in favour of particles >19 mm prepartum. In contrast, cows fed CAS showed an increase in selective consumption of fine particles and sorted against longer particles similar to the HCLK and LCLK groups. Postpartum sorting activity was not affected by the dietary treatments. After calving, apparent digestibility of NDF was significantly reduced in the HCLK group. Prepartum, we observed effects on serum concentrations of non‐esterified fatty acids were higher and insulin sensitivity was lower in the AMS group. Blood urea nitrogen (BUN) was decreased in cows fed the CAS ration. Postpartum, we found serum protein to be decreased with the low DCAD diets while BUN was decreased in the CAS group. The low DCAD rations increased prepartum serum malondialdehyde concentrations, while postpartum total antioxidant capacity was lower in the HCLK and the AMS group. From these data, we conclude that AMS decreased prepartum intake due to compromised palatability. Intermediate protein metabolism was affected by the low DCAD diets, while parameters of oxidative stress were probably affected by acid–base balance and Ca homeostasis. [ABSTRACT FROM AUTHOR]

In spite of generous supply with vitamin D3, Ca and P via complete diets non-infectious skeletal disorders are frequently observed in conventional broiler fattening. Especially fast-growing genotypes are affected. Because undersupply of nutrients for bone metabolism is generally suspected, vit D3 and Ca/P containing drinking-water additives are administered preventively as well as therapeutically. Therefore, this study was conducted to test potential effects of this widespread procedure. 240 male broilers (Cobb 500TM) were allotted to two subsequent trials with four groups each for a 35 day fattening period (day 1 till day 36). Broilers were housed on wood shavings and infrared lamps were initially used as heater. Water and feed were offered ad libitum. All animals were fed the same commercial starter, grower and finisher diets (215/205/195 g XP, 10/8.5/8 g Ca, 6.5/5.5/5 g P, 5000/4400/5000 I.U. vit. D/kg). The groups (treatments) only differed in the kind of additional supply via drinking water; group I (control group): no additional supply; group II: vit. D3 (1250 I.U./animal and day) at day 3 and 4; group III: Ca/P at day 5, 6, 15, 16, 23 and 24 (77 mg P and 24 mg Ca/l water); group IV: both vit. D and Ca/P. Six broilers of each group were sacrificed at day 6, 8, 16, 24 and 36 of the fattening period. Neither the extra supply of vit. D (doses: 200-fold of minimum requirement at both days) nor an additional intake of Ca and P clearly resulted in positive effects on performance or Ca and P metabolism or skeleton health throughout the whole trials. A subsequent trial (III), shortened to 7 days, was performed with 18 Ross 308® broilers. Calbindin, a protein which affects the active, vitamin D-dependent, transcellular Ca-transport, was examined in the small intestinal mucosa of these animals using a Western Blotting technique. Although applied via drinking water, absorption of vit. D was definitively demonstrated, subsequent increase of active Ca-absorption (calbindin D28K) did not occur, indicating that there is no need for an active transport at dietary Ca and P levels that meet requirements. [ABSTRACT FROM AUTHOR]