C. C. Calvert

Energy and micronutrient composition of dietary and medicinal wild plants consumed during drought. Study of rural Fulani, northeastern Nigeria.

Two rural settled Fulani villages, northeastern Nigeria, were surveyed for dietary practices and use of edible wild plants (n = 100 households). Commonly consumed species of edible wild barks, fruits, leaves, nuts, seeds, and tubers were analyzed for protein, fat, and carbohydrate and for minerals. Kuka bark (Adansonia digitata) given to infants to increase weight gain was high in fat, calcium, copper, iron, and zinc. Cediya (Ficus thonningii), dorowa (Parkia biglobosa) and zogale (Moringa oleifera) were good sources of protein and fat and excellent sources of calcium and iron or copper and zinc. Fruits, leaves, and nuts of aduwa (Balanites aegyptiaca) were widely used during the dry season and during drought. Edible wild species available during the wet season generally were inferior in energy and micronutrient mineral content compared to dry season plants. Fruits commonly eaten by children were poor sources of protein and minerals but rich in carbohydrate and fiber. Tsamiya seeds (Tamarindus indica) were good sources of zinc and used to make dawwa (porridge) commonly consumed during pregnancy. Kirya seeds (Prosopos africana) contained the highest zinc concentrations. Shiwaka leaves (Veronia colorate) consumed by pregnant women to increase breastmilk production and to expel intestinal worms, were high in fiber, phosphorus, magnesium, manganese, and were adequate sources of calcium.Two rural settled Fulani villages, northeastern Nigeria, were surveyed for dietary practices and use of edible wild plants (n = 100 households). Commonly consumed species of edible wild barks, fruits, leaves, nuts, seeds, and tubers were analyzed for protein, fat, and carbohydrate and for minerals. Kuka bark (Adansonia digitata) given to infants to increase weight gain was high in fat, calcium, copper, iron, and zinc. Cediya (Ficus thonningii), dorowa (Parkia biglobosa) and zogale (Moringa oleifera) were good sources of protein and fat and excellent sources of calcium and iron or copper and zinc. Fruits, leaves, and nuts of aduwa (Balanites aegyptiaca) were widely used during the dry season and during drought. Edible wild species available during the wet season generally were inferior in energy and micronutrient mineral content compared to dry season plants. Fruits commonly eaten by children were poor sources of protein and minerals but rich in carbohydrate and fiber. Tsamiya seeds (Tamarindus indica) were good sources of zinc and used to make dawwa (porridge) commonly consumed during pregnancy. Kirya seeds (Prosopos africana) contained the highest zinc concentrations. Shiwaka leaves (Veronia colorate) to increase breastmilk production and to expel intestinal worms, were high in fiber, phosphorus, magnesium, manganese, and were adequate sources of calcium.

The effect of an acute phase response on tissue carotenoid levels of growing chickens (Gallus gallus domesticus)

Plasma, liver and skin carotenoids decrease following infectious disease challenges. Since these challenges often involve substantial host pathology and chronic immune responses, the mechanism underlying altered carotenoid deposition is unclear. Therefore, changes in tissue carotenoid levels were examined during an acute phase response induced by lipopolysaccharide (LPS) or interleukin-1 (IL-1). In two experiments, chicks were hatched from carotenoid-deplete eggs (n=28, n=64, respectively) and fed 0, 8 or 38 mg carotenoids (lutein+canthaxanthin)/kg diet. For chicks fed 38 mg carotenoids, but not those fed 0 or 8 mg, LPS generally reduced plasma lutein, canthaxanthin and total carotenoids (P<0.05), and liver lutein, zeaxanthin, canthaxanthin and total carotenoids (P<0.05). Additionally, LPS reduced thymic total carotenoids (P=0.05) and increased thymocyte lutein (P=0.07), zeaxanthin (P=0.07) and total carotenoids (P=0.07). Finally, LPS increased bursal canthaxanthin (P<0.01), but had no effect on shank carotenoids (P>0.5). In chicks hatched from carotenoid-replete eggs (n=36) and fed dietary lutein (38 mg/kg diet), LPS reduced plasma and liver zeaxanthin and liver total carotenoids (P<0.05); IL-1 reduced plasma and liver lutein, zeaxanthin and total carotenoids (P<0.05). Therefore, an acute phase response plays a role in reduced tissue carotenoids during infectious disease.

Regulation of insulin-like growth factor-l and binding protein-3 expression in oMtla-oGH transgenic mice

Growth hormone (GH)-transgenic mice provide a model for studying hormonal regulation of gene products responsible for efficient lean growth. Insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (BP-3) are two products involved in mediating the growth promoting actions of GH. Mice carrying the ovine metallothionein la-ovine growth hormone (oMtla-oGH) transgene were used to study GH regulation of IGF-I and PB-3 expression because these mice do not exhibit elevated basal oGH levels without transgene stimulation by exogenous zinc. C57B1/6XCBA mice with (transgenic=TG) and without (control=C) the oMtla-oGH transgene were activated (+Zn) or inactivated (-Zn) by the addition or removal of 25 mM zinc sulfate in the drinking water. Plasma IGF-I and BP-3 levels were determined by radioimmunoassay and western ligand blotting, respectively. Hepatic IGF-I and BP-3 mRNA levels were determined by slot-blot analysis. TG+Zn mice had higher plasma IGF-I (p<0.05) and hepatic IGF-I mRNA (p<0.05) levels as compared to TG-Zn, C+Zn and C-Zn mice. Plasma IGF-I and hepatic IGF-I mRNA levels in TG-Zn mice were not different from C+Zn and C-Zn mice. Removal of Zn decreased hepatic IGF-I mRNA levels to C levels in TG mice. Plasma BP-3 and hepatic BP-3 mRNA levels in TG+Zn mice were increased (p<0.05) as compared to TG-Zn, C-Zn and C+Zn. Plasma BP-3 and hepatic BP-3 mRNA levels did not differ between TG-Zn, C-Zn and C+Zn mice. Expression of the transgene also increased the level of plasma BP-3 during pregnancy as compared to that observed for pregnant C mice. We conclude that oGH regulates IGF-I and BP-3 expression in the oMtla-oGH transgenic mouse model system.

Dietary restriction reduces the rate of estradiol clearance in sheep (Ovis aries)

Three experiments were designed to test the effect of dietary restriction on clearance of 17beta-estradiol (E(2)) in sheep. A preliminary experiment examined the effect of a 4-d fast on the rate of E(2) clearance in wethers. The second experiment tested the hypothesis that either long-term restriction (7 wk) or a 5-d fast would increase steroid-binding capacity of serum by increasing the concentration of sex hormone-binding globulin (SHBG) in the blood of ovariectomized ewes. In Exp. 3, we hypothesized that nutrition-dependent regulation of E(2) clearance by the liver would result in divergence in biliary extraction of E(2) in fed and fasted wethers receiving comparable levels of exogenous E(2). A marked difference in E(2) clearance between fed and fasted wethers was noted in the preliminary study. Relative to ad libitumfed wethers, a 4-d fast decreased E(2) clearance by 52%. Serum concentrations of SHBG were increased in long-term energy-restricted and fasted ewes, relative to the concentration in maintenancefed ewes (P = 0.015). Furthermore, a 5-d fast nearly doubled serum steroid-binding capacity in wethers. The E(2) concentration in bile was 2 times greater in fasted than in fed wethers. This fasting-dependent increase in biliary E(2) may be reflective of the increased serum E(2) in fasted animals, because each 1 pg/mL increase in serum E(2) increased bile E(2) by 0.86 +/- 0.12 pg/mL, independent of nutrition (P = 0.002). Our results demonstrate that the rate of clearance of E(2) is decreased during nutritional restriction. Additionally, these data indicate that altered SHBG expression, enterohepatic recirculation, or both are involved in the decreased E(2) clearance during dietary restriction.

Effects of supplementation and stocking rate on body condition and production parameters of multiparous beef cows

Fall-calving multiparous Angus × Hereford cows 3 to 10 years of age were stratified by age in a three by two factorial treatment arrangement to evaluate the efficacy of modifying stocking rate and supplementation strategy to manage cow body condition and production parameters over a 5-year study. Efficacy was evaluated quarterly in association with calving, breeding, weaning, and mid way between weaning and calving (i.e. in August). Three protein supplementation strategies (none, standard, strategic) were imposed across both a moderate (0·3 cows per ha) and a high (0·4 cows per ha) stocking rate. In the strategically supplemented group, protein supplement was provided to cows with a body condition score P P = 0·003 and P = 0·10, respectively). Standard, non-supplemented and strategically supplemented animals had estimated pregnancy rates of 0·83, 0·76, and 0·79, respectively ( P = 0·10). The effects of nutrition on both calving interval and birth weight were independent of the model employed. Animals that were not supplemented had extended calving intervals ( P = 0·06), but there was no effect of stocking rate ( P > 0·10). Birth weight was not affected by supplementation strategy or stocking rate ( P > 0·10). The lower 205-day weights of calves on a heavy compared with moderate stocking rate was independent of age ( P = 0·02). However, the increased 205-day weight of calves born to strategically supplemented cows compared with those born to unsupplemented cows was only evident when data were not corrected for differences in age among groups ( P = 0·03). Likewise, analyses of cow condition parameters using models without and with age resulted in different interpretations. These results suggest that strategic and standard supplementation result in similar animal performance and that the improvement in herd productivity associated with altering stocking rate and supplementation may partially be due to altered herd age dynamics.

Source of amino acids for tRNA acylation in growing chicks

SummarySpecific radioactivity in three amino acid compartments was examined in broiler chicks following a flooding dose of leucine or phenylalanine. In general, specific radioactivity of leucine and phenylalanine in deproteinated plasma (SAe) and tissue (SAi) compartments, exceeded that in acylated-tRNA (SAt). In most tissues, SAe and SAi rapidly reached a similar peak level by 5 min followed by a slow decline for the next 30 minutes. Many tissues (eg. GI tract, liver, skin, and thigh) failed to maintain equilibrium between SAe and SAi over time. More metabolically active tissues, such as GI and liver had the greatest differences between these compartments. The difference between SAe and SAi for both leucine and phenylalanine were due to SAi decreasing faster than SAe, indicating dilution with unlabelled amino acids from proteolysis. Plasma and tissue specific radioactivity overestimated tRNA specific radioactivity by as much as 5 and 2.8 fold using leucine or 2.7 and 1.4 fold using phenylalanine, respectively. These data suggest that intracellular compartmentation of protein metabolism and the coupling of protein degradation and synthesis occur, in vivo.

On the application of compartmental models to radioactive tracer kinetic studies of in vivo protein turnover in animals.

A mathematical framework is presented for unifying and extending the various compartmental models and formulae used to calculate fractional protein synthesis and degradation rates in animals from data obtained by infusing labelled amino acids. It is shown how the various schemes can be derived as special cases of the product-precursor model or some three-pool variant. Three-compartment representations, which circumvent the need to measure the specific radioactivity of the precursor pool, are proposed. The mathematical solutions are generally presented in a form that is amenable to parameter estimation by non-linear least squares. The problems of measuring the true precursor pool for protein synthesis are addressed, and theoretical consideration is given to assaying aminoacyl-tRNA.

Impact of separating amino acids between plasma, extracellular and intracellular compartments on estimating protein synthesis in rodents.

Summary. Three models representing different separations of amino acid sources were used to simulate experimental specific radioactivity data and to predict protein fractional synthesis rate (FSR). Data were from a pulse dose of 14C-U Leu given to a non-growing 20 g mouse and a flooding dose of 3H Phe given to a non-growing 200 g rat. Protein synthesis rates estimated using the combined extracellular and intracellular (Ec + Ic) source pool and extracellular and plasma (Ec + Pls) source pool mouse models were 78 and 120% d−1 in liver, 14 and 16% d−1 in brain and 15 and 14% d−1 in muscle. Predicted protein synthesis rates using the Ec + Ic, Ec + Ic + Tr (combined extracellular, intracellular and aminoacyl tRNA source pool) and Ec + Pls rat models were 57, 3.4 and 57% d−1 in gastrocnemius, 58, 71 and 62% d−1 in gut, 8.3, 8.4 and 7.9% d−1 in heart, 32, 23 and 25% d−1 in kidney, 160, 90 and 80% d−1 in liver, 57, 5.5 and 57% d−1 in soleus and 56, 3.4 and 57% d−1 in tibialis. The Ec + Ic + Tr model underestimated protein synthesis rates in mouse tissues (5.0, 27 and 2.5% d−1 for brain, liver and muscle) and rat muscles (3.4, 5.5 and 3.4% d−1 for gastrocnemius, soleus and tibialis). The Ec + Pls model predicted the mouse pulse dose data best and the Ec + Ic model predicted the rat flooding dose data best. Model predictions of FSR imply that identification and separation of the source specific radioactivity is critical to accurately estimate FSR.

Bioavailability of lysine for kittens in overheated casein is underestimated by the rat growth assay method.

Growth assays were performed to determine lysine bioavailability for kittens and rats in untreated and heated casein; these values were compared with estimates obtained with an in vitro method. Body weight, food intake, nitrogen and dry matter digestibility, and plasma lysine were determined during an 80-day growth trial using kittens (n = 16). Body weight and food intake were determined during a 21-day growth trial using weanling rats (n = 80). The growth data showed bioavailable lysine to be 102.4% and 100.2% (for untreated casein) and 66.1% and 51.7% (for heated casein) for kittens and rats, respectively. There was no relationship between plasma lysine and dietary lysine concentrations for kittens. There were no significant differences in nitrogen or dry matter digestibility among diets for kittens. The chemically reactive lysine content of untreated casein was 99.6%, and of heated casein was 67.1%. Heat treatment of casein resulted in significantly decreased lysine bioavailability as estimated by all methods. For untreated casein, both growth assays showed good agreement with the in vitro method for available lysine. For heated casein, the rat growth assay significantly underestimated bioavailable lysine as determined in kittens while the in vitro method closely approximated this value for the cat.

ORIGINAL ARTICLE: Bioavailability of lysine for kittens in overheated casein is underestimated by the rat growth assay method*,†: Lysine bioavailability for rats and cats

Growth assays were performed to determine lysine bioavailability for kittens and rats in untreated and heated casein; these values were compared with estimates obtained with an in vitro method. Body weight, food intake, nitrogen and dry matter digestibility, and plasma lysine were determined during an 80-day growth trial using kittens (n = 16). Body weight and food intake were determined during a 21-day growth trial using weanling rats (n = 80). The growth data showed bioavailable lysine to be 102.4% and 100.2% (for untreated casein) and 66.1% and 51.7% (for heated casein) for kittens and rats, respectively. There was no relationship between plasma lysine and dietary lysine concentrations for kittens. There were no significant differences in nitrogen or dry matter digestibility among diets for kittens. The chemically reactive lysine content of untreated casein was 99.6%, and of heated casein was 67.1%. Heat treatment of casein resulted in significantly decreased lysine bioavailability as estimated by all methods. For untreated casein, both growth assays showed good agreement with the in vitro method for available lysine. For heated casein, the rat growth assay significantly underestimated bioavailable lysine as determined in kittens while the in vitro method closely approximated this value for the cat.