Biology subjects

Brugger, D.

Publications and source records attributed to Brugger, D..

4 recordsLinked to original sources

bioRxiv2024

Temporary suspension of mineral phosphorus reduces mobilizable bone zinc in adult laying hens irrespective of the dietary zinc supply

This study examined the effects of short-term dietary zinc (Zn) and phosphorus (P) variations on the mobilizable bone Zn pool and overall Zn status in adult laying hens. Forty-eight hens (50% Lohmann Brown Classic, 50% Lohmann LSL Classic) were housed in pairs (one hen per breed per pen) across 24 pens. The pens were randomly assigned to one of two dietary P levels (0.37% or 0.84% in DM) using a high-protein corn-soybean diet (11.4 MJ AME/kg, 21.5% CP) during a 14-day acclimatization period. Following acclimatization, pens from both P groups were further randomized into four dietary treatments in a 2 x 2 factorial design, varying in P levels (low vs. high) and Zn supplementation (28 vs. 131 mg/kg) over an 8-day experimental feeding phase. Performance metrics, egg production and quality, and tissue mineral concentrations (plasma, liver, bone, and eggs) were measured. Statistical analyses were performed using linear mixed models in SAS 9.4, incorporating random effects of pen nested within treatment group and fixed effects of dietary P, dietary Zn, breed, and their interactions. Tukey-corrected 95% confidence intervals were used to estimate effect differences, with significance set at P < 0.05. Performance metrics, including egg production and body weight, were unaffected by dietary treatments (P > 0.1), indicating no clinical symptoms of Zn deficiency. However, hens on low-Zn diets exhibited significant reductions in plasma Zn concentration (-0.83 mg/L; P = 0.0008) and liver Zn concentration (-6.78 mg/kg DM; P = 0.01), confirming subclinical Zn deficiency. Low-Zn diets also increased the femoral molar Ca:P ratio by 0.15 (P = 0.01), irrespective of dietary P supply. Interestingly, low-P diets led to a significant reduction in femur Zn content (-0.46 mg; P = 0.0009), regardless of Zn supplementation, following 21 days of reduced P feeding. These findings highlight the higher susceptibility of laying hens to phytate antagonism compared to broilers, as evidenced by measurable subclinical Zn deficiency under short-term Zn deprivation. Additionally, a temporary suspension of mineral P supply appeared to impair the mobilizable bone Zn pool. The underlying functional mechanisms driving these interactions remain unclear and warrant further investigation.

physiology↗

bioRxiv2024

Effects of excess dietary calcium supplementation during the transition phase on calcium and bone metabolism of dairy sheep and goats and growth response of their suckling offspring

Interpretive SummaryMany studies have focused on the effects of deficient Ca supply in small dairy ruminants, while little is known about the impact of high dietary Ca intake during the last days before parturition. Here, we show that multiparous dairy goats and sheep maintained Ca homeostasis despite receiving a high dietary Ca supply, with no adverse consequences for their health. However, we observed that animals fed the high dietary Ca diet antepartum showed a gradual increase in serum osteocalcin postpartum, and their suckling offspring exhibited reduced average daily weight gain. The functional background and practical consequences of these findings are yet unknown and may guide future research on the matter. This study investigated the effects of high dietary Ca supplementation during the final 21 days antepartum on Ca and bone homeostasis in dairy sheep and goats, and the growth response of their suckling offspring. Multiparous dairy sheep (n = 5/group, 10 animals total) and goats (n = 6/group, 12 animals total) were randomly assigned to 2 experimental groups. Feeding occurred restrictively (2.3 kg DM/d*animal-1 antepartum for both species; 2.9 and 3.1 kg DM/d*animal-1 for sheep and goats postpartum, respectively) according to recommendations, except for Ca during antepartum feeding: 1 group received the basal diet based on hay and concentrate with extra CaCO3 (1.3% Ca in DM; 2.49-fold the recommendations) for 3 weeks antepartum, while the other group received just the basal diet (0.6% Ca in DM; 1.15-fold the recommendations). Experimental feeding ended with parturition and animals were henceforth fed according to Swiss recommendations for lactating sheep and goats and kept together with their suckling offspring. The observation period spanned from 21 days antepartum to 56 days postpartum. Animals were under continuous veterinary surveillance and monitored for signs of milk fever. Data collection comprised quantitative and functional parameters of Ca and bone homeostasis as well as birth weights and daily weight gain of suckling lambs and kids. Data were analyzed using repeated measures and endpoint mixed models. The response of quantitative markers indicated that high dietary Ca antepartum significantly increased fecal Ca concentrations until parturition, suggesting efficient physiological mechanisms to manage Ca overload through increasing fecal excretion. No significant differences were observed in serum Ca levels, urinary Ca excretion, or bone mineral density between the antepartum Ca feeding groups at any point during the observation period, indicating stable Ca homeostasis despite the dietary challenge. Differences in quantitative markers were noted between sheep and goats, including variations in serum and colostral Ca levels and bone mineral density, which largely aligned with results from earlier comparative studies. Serum 1,25-(OH)2 vitamin D (calcitriol) as well as markers of bone formation and resorption were monitored, revealing significant increases in serum osteocalcin postpartum in both goats and sheep fed high Ca antepartum. However, all other serum markers including calcitriol, remained unaffected by the feeding regime but differed between sheep and goats, consistent with previous findings. All repeated measures were significantly affected by time, except for urinary Ca and bone-specific alkaline phosphatase activity in serum. Suckling offspring of sheep and goats in the high Ca group exhibited significantly reduced average daily weight gain compared to those in the 0.6 % in DM Ca group, despite similar birth weights. We conclude that while dairy sheep and goats effectively managed high dietary Ca intake without overt signs of hypocalcemia or milk fever under these experimental conditions, the observed impacts on offspring growth and potential long-term physiological effects warrant further investigation. These findings contribute to the understanding of mineral nutrition in late-gestating dairy goats and sheep and highlight the need for further research on balanced dietary strategies to optimize health and productivity of dairy sheep and goats and their offspring. Key words: Transition phase, Calcium Homeostasis, Small Ruminant, Maternal Nutrition Nonstandard abbreviations: bAP = bone-specific alkaline phosphatase activity; BMD = bone mineral density; calcitriol = 1,25-(OH)2 vitamin D; CTX = crosslaps;; ICTP = crosslinked carboxyterminal teleopeptide of type I collagen; VDR = vitamin D receptor

physiology↗

bioRxiv2020

Varying trypsin inhibitor activity in differently processed soybean expellers linearly reduces prececal amino acid digestibility in broilers

The present study investigated the effect of varying trypsin inhibitor activity (TIA) in differently processed soybean expellers on apparent prececal amino acid (AA) digestibility in male broiler chickens. Two different raw soybean batches were treated using four different processing techniques (thermal, hydrothermal, pressure, kilning) at varying intensities. In this way, 45 expeller extracted soybean meal (ESBM) variants were created. The processed soybean variants were then merged into a basal diet (160 g/kg crude protein (CP)) at two inclusion levels (15%, 30%) resulting in 91 different diets (1 basal diet plus 90 experimental diets) with TIA ranging from 0.4 mg/g to 8.5 mg/g. All diets contained 0.5% of titanium dioxide (TiO2). During four experimental runs, a total of 5,460 1-day old male broiler chickens (Ross 308) were fed a commercial starter diet (CP 215 g/kg, 14 g/kg Lysine, 12.5 MJ ME/kg) ad libitum from day 1 to day 14. Subsequently, birds were allocated to a total of 546 pens with 10 birds per pen and were fed the 91 experimental diets ad libitum. At day 22, birds were sacrificed and digesta of the terminal ileum was collected for determination of AA digestibility. TIA depressed the prececal digestibility of every single AA significantly in a straight linear fashion (p < 0.001). cystine and methionine expressed the strongest suppression by TIA with cystine showing the lowest apparent prececal digestibility measured (4.94% at 23.6 mg/g TIA in raw ESBM). Correspondingly, live weight (LW) (p < 0.001) and total weight gain (TWG) (p < 0.001) declined in a linear manner with increasing TIA in feed. The present data demonstrate that TIA severely depresses digestibility of essential and non-essential AA and thus growth performance in a straight linear fashion. On the one hand, this questions the usefulness of defined upper limits of TIA in soy products whereas on the other hand, TIA must be considered when testing raw components for their feed protein value in vivo.

physiology↗

bioRxiv2020

Zinc transporter gene expression in pigs with subclinical zinc deficiency

This study compared the relative mRNA expression of all mammal zinc (Zn) transporter genes in selected tissues of weaned piglets challenged with short-term subclinical Zn deficiency (SZD). The dietary model involved restrictive feeding (450 g/animal*day-1) of a high-phytate diet (9 g/kg) supplemented with varying amounts of zinc from ZnSO4*7H2O ranging from deficient to sufficient supply levels (total diet Zn: 28.1, 33.6, 38.8, 42.7, 47.5, 58.2, 67.8, 88.0 mg Zn/kg). Total RNA preparations comprised jejunal and colonic mucosa as well as hepatic and nephric tissue. Statistical modelling involved broken-line regression (P [≤] 0.05). ZIP10 and ZIP12 mRNAs were not detected in any tissue and ZnT3 mRNA was only identified in the kidney. All other genes were expressed in all tissues but only a few gene expression patterns allowed a significant (P < 0.0001) fitting of broken-line regression models, indicating homeostatic regulation under the present experimental conditions. Interestingly, these genes could be subcategorized by showing significant turnarounds in their response patterns, either at ~40 or ~60 mg Zn/kg diet (P < 0.0001). In conclusion, the present study showed clear differences in Zn transporter gene expression in response to SZD compared to the present literature on clinical models. We recognized that certain Zn transporter genes were regulated under the present experimental conditions by two distinct homeostatic networks. For the best of our knowledge, this represents the first comprehensive screening of Zn transporter gene expression in a highly translational model to human physiology.

physiology↗