M. Lachica

The energy costs of walking on the level and on negative and positive slopes in the Granadina goat ( Capra hircus )

The energy expenditure of six goats averaging 35 (SE 0.3) kg was measured when the animals were standing or walking on a treadmill enclosed in a confinement-type respiration chamber at different speeds (0.167, 0.333 and 0.500 m/s) and slopes (-10, -5, 0, +5 and +10%). The energy costs of locomotion, estimated from the coefficients of linear regressions of heat production (HP) per kg body weight v. distance travelled were 1.91, 2.33, 3.35, 4.68 and 6.44 J/kg BW per m for -10, -5, 0, +5 and +10% inclines respectively, indicating that the energy expenditure of walking over standing changes with slope according to a slightly curvilinear relationship. The energy cost of raising 1 kg body weight one vertical metre was found to be 31.7 J, giving an average efficiency for upslope locomotion of 30.9%. The energy recovered on vertical descent was estimated as 13.2 J/kg per m, indicating an efficiency of the energy recovered above the theoretical maximum.

Impact of dietary betaine and conjugated linoleic acid on insulin sensitivity, protein and fat metabolism of obese pigs

To determine possible mechanisms of action that might explain the nutrient partitioning effect of betaine and conjugated linoleic acid (CLA) in Iberian pigs and to address potential adverse effects, twenty gilts were restrictively fed from 20 to 50 kg BW Control, 0.5% betaine, 1% CLA or 0.5% betaine + 1% CLA diets. Serum hormones and metabolites profile were determined at 30 kg BW and an oral glucose test was performed before slaughter. Pigs were slaughtered at 50 kg BW and livers were obtained for chemical and histological analysis. Decreased serum urea in pigs fed betaine and betaine + CLA diets (11%; P = 0.0001) indicated a more efficient N utilization. The increase in serum triacylglycerol (58% and 28%, respectively; P = 0.0098) indicated that CLA and betaine + CLA could have reduced adipose tissue triacylglycerol synthesis from preformed fatty acids. Serum glucose, low-density lipoprotein (LDL) cholesterol and non-esterified fatty acids were unaffected. CLA and betaine + CLA altered serum lipids profile, although liver of pigs fed CLA diet presented no histopathological changes and triglyceride content was not different from Control pigs. Compared with controls, serum growth hormone decreased (20% to 23%; P = 0.0209) for all treatments. Although serum insulin increased in CLA, and especially in betaine + CLA pigs (28% and 83%; P = 0.0001), indices of insulin resistance were unaffected. In conclusion, CLA, and especially betaine + CLA, induced changes in biochemical parameters and hormones that may partially explain a nutrient partitioning effect in young pigs. Nevertheless, they exhibited weak, although detrimental, effects on blood lipids. Moreover, although livers were chemically and histologically normal, pigs fed CLA diet challenged with a glucose load had higher serum glucose than controls.

Influence of betaine and conjugated linoleic acid on development of carcass cuts of Iberian pigs growing from 20 to 50 kg body weight

Twenty Iberian gilts (20 kg body weight, BW) were fed diets containing no betaine or conjugated linoleic acid (CLA) (Control), 0.5% betaine, 1% CLA, or 0.5% betaine+1% CLA. Additionally, 5 pigs were killed at 20 kg BW for the initial points of the allometric equations. At 50 kg BW, left semicarcasses were cut into primal cuts, hams and shoulders trimmed and dissected. CLA alone did not affect any analyzed parameter. Betaine increased (23 and 21%, respectively) the yield of shoulder butt and spine and decreased allometric growth coefficient of belly and backfat, compared to Control diet. Tenderloins and trimmed hams of pigs fed CLA+betaine diet developed later and were heavier (22 and 5%, respectively) than Control pigs. Also, leaf fat developed earlier and had lighter weight (32%). Furthermore, pigs fed CLA+betaine diet had heavier lean (5%) and fat free lean (6%) of shoulders compared to Control pigs.

Metabolic regulation of fatty acid esterification and effects of conjugated linoleic acid on glucose homeostasis in pig hepatocytes.

Conjugated linoleic acids (CLAs) are geometric and positional isomers of linoleic acid (LA) that promote growth, alter glucose metabolism and decrease body fat in growing animals, although the mechanisms are poorly understood. A study was conducted to elucidate the effects of CLA on glucose metabolism, triglyceride (TG) synthesis and IGF-1 synthesis in primary culture of porcine hepatocytes. In addition, hormonal regulation of TG and IGF-1 synthesis was addressed. Hepatocytes were isolated from piglets (n = 5, 16.0 ± 1.98 kg average body weight) by collagenase perfusion and seeded into collagen-coated T-25 flasks. Hepatocytes were cultured in Williams E containing dexamethasone (10-8 and 10-7 M), insulin (10 and 100 ng/ml), glucagon (0 and 100 ng/ml) and CLA (1 : 1 mixture of cis-9, trans-11 and trans-10, cis-12 CLA, 0.05 and 0.10 mM) or LA (0.05 and 0.10 mM). Addition of CLA decreased gluconeogenesis (P < 0.05), whereas glycogen synthesis and degradation, TG synthesis and IGF-1 synthesis were not affected compared with LA. Increased concentration of fatty acids in the media decreased IGF-1 production (P < 0.001) and glycogen synthesis (P < 0.01), and increased gluconeogenesis (P < 0.001) and TG synthesis (P < 0.001). IGF-1 synthesis increased (P < 0.001) and TG synthesis decreased (P < 0.001) as dexamethasone concentration in the media rose. High insulin/glucagon increased TG synthesis. These results indicate that TG synthesis in porcine hepatocytes is hormonally regulated so that dexamethasone decreases and insulin/glucagon increases it. In addition, CLA decreases hepatic glucose production through decreased gluconeogenesis.

The 13C-bicarbonate method: its suitability for estimating the energy expenditure in grazing goats

Two main experiments were carried out with adult goats of the Granadina breed to obtain information on the suitability of the carbon dioxide entry rate (CER) technique using 13C-bicarbonate to estimate CO2 production and subsequently the energy expenditure of animals performing variable physical activity. The purpose was to validate this method for application to the grazing animal. The goats were accustomed to spending long periods of time in an open-circuit respiration chamber and 5 days prior to the start of the experiments they were prepared with catheters into the jugular vein (infusion of 13C-bicarbonate) and the parotid salivary duct (sampling). Bicarbonate from saliva samples was converted to BaCO3 and the 13C/12C ratio were determined in a gas isotope ratio mass spectrometer. Experiment 1 was performed to determine the effect of exercise on the levels of 13C natural abundance. Saliva samples were collected from each of six animals over 2 h periods to measure the natural abundance of 13C (at% 13C) in non-exercised goats prior to infusion. Subsequently, each goat was walked on a treadmill at zero gradient for 30 min at 20 m min−1. The treadmill belt was stationary during periods of 45 min pre and post the walking activity. Saliva samples were taken during each 2 h period (each comprising 30 min walking preceded and followed by 45 min standing), which were replicated at least four times. The average natural abundance of 13C was 1.09656 and 1.09363% for the resting and intermittently exercised animals, respectively (P<0.05). Experiment 2 was performed to establish the relationships between values of CO2 production obtained by calorimetry and the CER technique in animals standing at rest or in the intermittent locomotion protocol assayed in Experiment 1. Five animals were individually placed into an open-circuit respiration chamber and continuously infused with 13C-bicarbonate for at least 15 h before starting saliva collection. Samples of saliva were taken over 2 h periods and concomitant measurements of CO2 production were made. Based on the ratio of CO2 production/CER, apparent mean recoveries of 13CO2 between resting and intermittent locomotion conditions were not significantly different (0.723±0.0437 and 0.779±0.0409, respectively). The absolute entry rate was slightly affected by the goats’ physical activity. The results show that the 13C-bicarbonate method appears to be a promising technique for measuring energy expenditure of the grazing goat.

The Role of Copper in the Structural Organization of Photosystem II in Chloroplast Membranes

It is well known that Cu deficiency has a direct impact on photosynthesis in affecting the synthesis of the Cu-containing electron carrier plastocyanin (1, 2). Some authors have suggested that Cu may influence electron transport either as a component of plastocyanin and/or in PSII. Droppa et al. (3) found that severe Cu deficiency inhibited PSII electron transport via changes of the fluidity of the thylakoid membranes. Sibbald and Green (4) found Cu was associated with PSII particles and that most of this PSII Cu is located in the light-harvesting chlorophyll/protein complex and therefore not directly involved in photosynthetic electron transport. They suggested a structural role of Cu in LHCII or its involvement in LHCII synthesis.

Root Uptake and Partition of Copper, Iron, Manganese, and Zinc in Pinus radiata Seedlings Grown under Different Copper Supplies

Summary In spite of the low Cu needs, a Cu2+ level of 0.03 µM in hydroponic cultures of Pinus radiata seedlings induces a Cu-deficient situation; under these conditions the foliar Cu was 4 mg·kg-1 dry wt after 2.5 months growth, which decreased to 1 mg kg-1 in 5-month-old seedlings. This is shown by a decrease of the growth rate with time, which appears negligible between 7.5 and 9 months in culture. The Cu content of roots, foliar and non-foliar stems, and leaves increases with the micronutrient concentration in the culture solutions, but the response of each organ is inversely related with its distance from the hydroponic medium. In any case P. radiata seedlings showed a very efficient Cu2+ absorption capability of the root, but the nutrient translocation to the aerial organs appears restricted, maybe as a protection mechanism. Until 7.5 months in culture the optimum plant development occurs under excess Cu2+, which shifts to normal Cu2+ levels after 9 months growth; this can be explained as a transient Cu deficiency during the first developmental stage. Mn absorption showed some type of antagonism with that of Cu2+, the needles being the site of the highest Mn concentration in pine. On the contrary, the rate of Fe absorption increases with Cu2+ levels, but the translocation to stems and leaves occurs very slowly. Zn showed a Z-shape partition pattern along root, stems, and needles, with the highest concentrations in root and foliar stem; in addition, Zn absorption appears to be antagonistic to that of Cu.

Low-cost mobile open-circuit hood system for measuring gas exchange in small ruminants: from manual to automatic recording

Table 2 contained an incorrect footnote. The correct version is supplied at: http://dx.doi.org/10.1017/S0021859615000556

Approaches for quantifying gastrointestinal nutrient absorption and metabolism in a native and a modern pig breed

When working with multi-catheterized animals, success and failure are separated by surgical procedures and minor details in catheter design and care. The current paper is a detailed description of novel approaches to multi-catheterization of pigs for investigations into nutrient absorption and metabolism of portal-drained viscera (PDV) in a native obese (Iberian) and a modern (Landrace) breed. Three Iberian and three Landrace gilts (25 kg average body weight; BW) were fitted with catheters in the carotid artery (CA), the portal vein (PV) and the ileal vein (IV). Tygon rings were attached to the catheter to mark the extent of introduction into the vessel and facilitate its fixing by means of a non-absorbable suture. The PV was catheterized through the visceral side of the left-lateral lobe of the liver and IV through a branch of the vein. The CA was secured directly in place with a purse-string suture where the artery was not occluded. Patency of the catheters was checked weekly and catheters filled with sterile heparinized saline and closed by two knots. Portal blood flow was determined to test the procedures. A 15 ml pulse dose of para-aminohippuric acid (PAH; 2% w/v) was infused into IV 45 min prior to blood sampling, followed by continuous infusion of 0·8 ml/min. Blood samples (4·5 ml) were taken simultaneously from CA and PV, using heparinized tubes, 5 min before feeding 0·25 of the total daily ration (barley–soybean meal diet; 160 g crude protein (CP)/kg; 14–14·5 MJ metabolizable energy (ME)/kg dry matter (DM); 2·4×ME for maintenance), and every 30 min for 4 h and then hourly until 6 h after feeding. Blood was centrifuged and plasma harvested and stored at −20 °C until PAH analysis. Whole-blood flow was based on the Fick principle. Post-prandial PDV blood flow was lower for the Iberian pigs than Landrace (866 and 1464 ml/min, respectively). The concurrence of access to the PV through the liver with a minimal wound, the non-occluded blood flow in CA, and the catheter design and care were all critical for the fast recovery of pigs and catheter patency. The procedures followed are recommended for studies of absorption of nutrients from the gastrointestinal tract and the impact of PDV on the metabolism of conscious, unrestrained, growing pigs.

Determination of copper in different chloroplast preparations

The determination of total Cu is not often correlated with states of deficiency in plant material. This fact makes it necessary to look for biologically active Cu. Suspensions of thylakoid membranes and photosystem II particles, properly diluted with 13 mM nitric acid, were used for this purpose. The presence of a minute quantity of an antifoaming agent, such as 1-octanol, is essential when an aliquot of the slurry is injected into the graphite furnace of the atomic absorption spectrophotometer. Good agreement was obtained between our results and those obtained by a classical dry combustion method. Reproducibility was better than 5% when expressed as relative standard deviation.