Embodied Resources in Fish and Shrimp Feeds

Global averages were obtained for amounts of energy, land, water, wildfish, nitrogen, and phosphorus embodied in aquaculture feed ingredients. These data allowed amounts of these embodied resources to be calculated for typical feed formulations for channel catfish, Ictalurus punctatus; hybrid catfish, I. punctatus♀ × I. furcatus♂; Vietnamese catfish, Pangasius spp.; Atlantic salmon, Salmo salar; rainbow trout, Oncorhynchus mykiss; tilapia, Oreochromis spp.; whiteleg shrimp, Litopenaeus vannamei; and black tiger shrimp, Penaeus monodon. Embodied resource use per m.t. of feed varied among species: energy, 4.90–12.48 GJ/m.t.; land, 0.082–0.312 ha/m.t.; water, 502–1227 m³/m.t.; wildfish, 0–2880 kg/m.t.; nitrogen, 3.08–8.63 kg/m.t.; phosphorus, 1.16–5.62 kg/m.t. These calculations did not account for variations in site‐specific factors related to embodied resources and feed composition and use. But they suggest that reducing feed conversion ratio (FCR) by 0.1 unit for the seven species (species groups) could potentially reduce feed use by around 1.1 million tonne (Mt) while conserving 9.8 million GJ of energy, 270,000 ha of agricultural land, 1.4 billion m³ of freshwater, and 1.24 Mt of wildfish. Reduction of the FCR is a powerful means of lessening farm‐level production costs and negative impacts of feed production and use.     

Spectral analysis of zooplankton spatial heterogeneity

Continuous estimates were obtained of zooplankton abundance, chlorophyll fluorescence, and water temperature along 10-to 100-kilometer transects of the North Sea. Spectral analysis methods were applied to the data. The "patchiness" of the plankton was distributed over all the length scales resolved with no indication of a characteristic patch size. The relative intensity of the zooplankton patchiness was greater than that of the phytoplankton at all spatial scales, with this difference becoming progressively greater for finer-scale features. In the North Sea data, the concentrations of phytoplankton and zooplankton consistently showed negative spatial correlations.     

Production of Lambs After the Transfer of Fresh and Cryopreserved in vitro Produced Embryos from Prepubertal Lamb Oocytes and Unsorted and Sex-sorted Frozen-thawed Spermatozoa

Cumulus-oocyte complexes from hormone-stimulated 3-4-week-old (n=43) and 6-7-week-old (n=12) prepubertal lambs were matured in vitro and incubated with unsorted, or X- or Y-spermatozoa separated with a high-speed cell sorter (SX MoFlo)frozen-thawed. Presumptive zygotes were then cultured to the blastocyst stage, and transferred to recipients fresh or after cryopreservation (frozen). Oocyte cleavage was higher (p <0.05) with unsorted (515/926, 55.6%) than X- or Y-spermatozoa (261/672, 38.8% and 229/651, 35.2%, respectively) and blastocyst formation (% zygotes) by Day 9 of in vitro culture was lower (p <0.05) for X- (102/261, 39.1%) than unsorted spermatozoa (249/515, 48.3%), but did not differ between Y-spermatozoa (103/229, 45.0%) and unsorted spermatozoa, or between X- and Y-spermatozoa (p >0.05). For fresh embryos, survival to term was 50.0% (3/6) for unsorted, 0.0% (0/6) for X- and 16.7% (1/6) for Y-spermatozoa-derived embryos (p >0.05), and for frozen embryos was 4.0% (2/50) for unsorted, 9.1% (2/22) for X- and 2.9% (1/34) Y-spermatozoa-derived embryos (p >0.05). Of the two lambs born from X-spermatozoa-derived embryos, one was female (50%), and from the two Y-spermatozoa-derived lambs, both were male (100%), demonstrating that lambs can be produced after the transfer of fresh and cryopreserved IVP embryos derived from prepubertal lamb oocytes and frozen-thawed sex-sorted sperm.     

Organic Carbon and Dissolved Oxygen Budgets for a Commercial‐Size,In‐pond Raceway System

Intensive production of ictalurid catfish in the USA has increased over the past several years, and a better understanding of the amount of organic carbon (OC) and dissolved oxygen (DO) in these culture environments is needed. Budgets for OC and DO were estimated over a production season (March to November) for an in‐pond raceway system for channel catfish, Ictalurus punctatus, and hybrid catfish (channel catfish × blue catfish, Ictalurus furcatus), with co‐culture of paddlefish, Polyodon spathula, and Nile tilapia, Oreochromis niloticus. Feed input ranged from 45 to 263 kg/ha/d with an overall average of 80 kg/ha/d. Production of each kilogram of live catfish required 1.5 kg of feed and released into the water 0.70 kg of OC, and led to the synthesis of an additional 3.36 kg of OC by photosynthesis. Consequently, production of 1 kg of live catfish resulted in 4.06 kg OC, and harvest of catfish accounted for only 29.5% of OC applied from the feed. Removal of OC increased to 34.3% with the additional harvest of paddlefish and tilapia. OC was consumed in respiration, and some OC accumulated in sediment. Total respiration within the system exceeded the DO produced by photosynthesis, while diffusion and mechanical aeration aided in maintaining suitable DO levels for fish production.     

Radiographic and functional evaluation of dogs at least 1 year after tibial plateau leveling osteotomy

The progression of osteoarthritis and clinical function in 29 dogs at least 1 year after tibial plateau leveling osteotomy was evaluated. A previously reported radiographic scoring system was used by 3 investigators to evaluate preoperative and postoperative radiographs for evidence of stifle osteoarthritis. The combined scores were then used to evaluate the progression of osteoarthritis. The difference between the preoperative scores, derived from radiographs taken at the time of surgery, and the postoperative scores based on radiographs taken at least 1 year later was modest but statistically significant. Despite this finding, client satisfaction was very good. Clinical function was assessed by using a previously reported client questionnaire. According to owner assessment at least 1 year after surgery, there was a significant improvement in function after tibial plateau leveling osteotomy when compared with the preoperative status. Improvement in function as measured by the client questionnaire did not significantly predict the radiographic osteoarthritis score.     

Lactation feed disappearance and weaning to estrus interval for sows fed spray-dried plasma

Four experiments involving 265, 410, 894, and 554 sows (Exp. 1 to 4, respectively) were conducted to determine the effect of spray-dried plasma (SDP) at 0 or 0.25% (Exp. 1 and 2) and 0 or 0.50% (Exp. 3 and 4) in lactation diets on average daily feed disappearance (FD), sum of sow BW, fetal and placental loss from d 110 gestation to weaning (SWL), litter size at weaning, litter weight at weaning, and average days from weaning to first estrus (WEI). Experiments 1, 3, and 4 were conducted during summer months, and Exp. 2 was conducted during fall to winter months. Experiment 1 used only parity 1 and parity 2 sows and Exp. 4 used only mature (>2 parities) sows, whereas Exp. 2 and 3 used all parity groups. Sows fed SDP in Exp. 1 had increased (P < 0.01) FD and a tendency for reduced (P = 0.06) SWL and WEI (P = 0.06). Sows fed SDP in Exp. 2 had a tendency for increased (P = 0.09) sow BW at weaning and reduced (P = 0.09) SWL, whereas other variables were not different between diets. Parity 1 and 2 sows fed SDP in Exp. 3 had increased (P < 0.01) FD, but mature sows fed SDP had reduced (P = 0.02) FD. Pig survival and litter size at weaning for all parity groups was not different between diets. The WEI for parity 1 sows fed SDP was reduced (P = 0.02) and tended to be reduced (P = 0.10) for mature sows fed SDP, but was not different between diets for parity 2 sows. More parity 1 sows fed SDP were detected (P = 0.01) in estrus 4 to 6 d after weaning, and fewer were detected (P < 0.01) in estrus 6 d after weaning compared with control parity 1 sows. In Exp. 4, FD was reduced (P < 0.01) for mature sows fed SDP; however, litter weight and average pig BW at weaning was increased (P < 0.01) with more (P < 0.01) marketable pigs (pig BW > 3.6 kg) weaned per litter. Relatively low dietary levels of SDP (0.25 to 0.50%) fed to parity 1 sows farrowed during summer months increased lactation FD and reduced WEI. Mature sows fed SDP during summer months consumed less lactation feed without compromising WEI, but had an increased litter weight, average pig BW, and number of marketable pigs at weaning.     

Analysis of amino acid uptake and translocation in Arabidopsis with a low‐cost hydroponic system

In soils, amino acids may be an important source of nitrogen for plants, at least in those where organic matter is not quickly degraded. The physiology of uptake of amino acids by roots was mainly studied in the 70's and 80's, before genes encoding amino acid importers were cloned in the 90's. While two families of amino acid transporters have been identified, yielding a total of about 100 genes, the role of each member is yet to be elucidated. As a tool for studying the role of amino acid transporters from Arabidopsis we set up a new hydroponic system suitable for radioisotope use. This system enables reproducible amino acid uptake by roots and estimation of the transport to the shoots of the amino acid taken up. We show that the rates of glutamine (Gln) uptake by wild‐type roots and transfer to the shoots were linear, and that other tested amino acids were translocated to the shoots with lower efficiency than Gln. A T‐DNA insertion mutant for a Gln exporter was compared to the wild‐type plants. Gln uptake and transfer were similar in both genotypes, showing that the suppression of the exporter did not affect uptake or transfer of amino acids to the shoots. The main advantage of the hydroponic system presented here is that all the materials used to grow Arabidopsis are virtually free and can therefore be discarded, a useful feature when working with radioactivity.     

The significance of small vs large intestinal digestion of cereal grain and oilseed protein in the equine

Mature ponies fitted with permanent ileal cannulas were used in two 3×3 Latin square experiments to quantify prececal, postileal and total tract digestion of N. In trial 1, corn, oats and sorghum were each fed with coastal Bermuda grass hay in 75:25 ratios. Apparent prececal digestibilities were similar (P>.05) and averaged 46.6%. By-difference procedures were employed to calculate digestibility of the cereal grain N only and apparent prececal N digestibility averaged 57.1%. In trial 2, a basal corn and hay diet was supplemented with cottonseed meal and soybean meal. Apparent total tract N digestibilities were similar (P>.05) across treatments, and prececal digestibility averaged 45.6%. By-difference calculations were used to determine digestibility of SBM and CSM N alone. Apparent prececal digestibility of SBM was 52.5% and was lower (P<.05) than 81.2% for CSM. It is possible that inadequate or excessive heat treatment of SBM affected enzymatic digestion. True digestibility of total rations fed in trial 2 was estimated by linear regression of nitrogen digested on nitrogen intake or N presented to the large intestine. True N digestibility of diets containing SBM and CSM was 54.7% and 69.4%, respectively.     

Relationships between acid-base balance, serum composition and colostrum absorption in newborn calves

Twenty-seven newborn Holstein bull calves were bottle-fed 2 litres of pooled colostrum which had been stored at -20 degrees C. Blood gas analysis before feeding showed a partially compensated respiratory acidosis in most of the calves, although they all appeared to be clinically normal. Mean venous blood pH was 7.346, carbon dioxide tension (PCO2) was 57.5 mmHg (7.6 kPa), bicarbonate was 30.6 mmol/l and base excess was 3.82 mmol/l. Mean serum IgG1 increased to 8.1 g/l after feeding colostrum. Several significant positive correlations were observed between post-absorptive serum protein, IgG1, IgM, gamma-glutamyltransferase (gamma GT) and D-xylose. Calves with either low serum albumin, high serum CK or low serum gamma GT before feeding tended to have less absorption of colostral protein. It was concluded that reduced absorption of IgG1 from colostrum is associated with hypercapnia in apparently healthy newborn calves.     

Measurement of 5-day biochemical oxygen demand without sample dilution or bacterial and nutrient enhancement

A direct method for measuring the 5-day biochemical oxygen demand (BOD₅) of aquaculture samples that does not require sample dilution or bacterial and nutrient enrichment was evaluated. The regression coefficient (R²) between the direct method and the standard method for the analyses of 32 samples from catfish ponds was 0.996. The slope of the regression line did not differ from 1.0 or the Y-intercept from 0.0 at P = 0.05. Thus, there was almost perfect agreement between the two methods. The control limits (three standard deviations of the mean) for a standard solution containing 15 mg/L each of glutamic acid and glucose were 17.4 and 20.4 mg/L. The precision of the two methods, based on eight replicate analyses of four pond water samples did not differ at P = 0.05.