Genetic Correlations Between Beef Traits Measured on Young Performance Test Bulls and Daughter Milk Yield

In a breeding programme where young potential breeding bulls are reared on performance test stations, selection based on own results can be carried out before test inseminations. Both beef and milk production traits are included in the total merit index used for selection, and estimates of genetic and phenotypic parameters of these traits are therefore of interest for an optimal construction of such indices. Data on first lactation milk records from the field and beef records of potential dairy breeding bulls from the Danish performance test stations were analysed in bivariate animal-sire models using the AI-REML algorithm. Genetic correlations of 0.16, 0.25 and 0.43 between feed intake capacity and protein yield were obtained for Red Danish (RD), Danish Black and White (DBW) and Danish Jersey (DJ), respectively. These correlations were significantly different from zero for the two populations (DBW and DJ). Genetic correlations around zero between feed efficiency and protein yield were obtained for all three populations. Genetic correlations of 0.44, 0.19 and 0.47 between average daily gain and protein yield were obtained for RD, DBW and DJ, respectively. The genetic correlations between protein yield and muscle area was close to zero for DBW, while it was -0.31 for RD. Selection index calculations indicate that indices composed of different beef performance traits can be used as early predictors for milk yield. Selection on such an index could increase the breeding value of the young bulls for milk production traits by 0.8-2.0% of the population mean.     

Evolution and Distribution of Saxitoxin Biosynthesis in Dinoflagellates

Numerous species of marine dinoflagellates synthesize the potent environmental neurotoxic alkaloid, saxitoxin, the agent of the human illness, paralytic shellfish poisoning. In addition, certain freshwater species of cyanobacteria also synthesize the same toxic compound, with the biosynthetic pathway and genes responsible being recently reported. Three theories have been postulated to explain the origin of saxitoxin in dinoflagellates: The production of saxitoxin by co-cultured bacteria rather than the dinoflagellates themselves, convergent evolution within both dinoflagellates and bacteria and horizontal gene transfer between dinoflagellates and bacteria. The discovery of cyanobacterial saxitoxin homologs in dinoflagellates has enabled us for the first time to evaluate these theories. Here, we review the distribution of saxitoxin within the dinoflagellates and our knowledge of its genetic basis to determine the likely evolutionary origins of this potent neurotoxin.     

Inorganic nitrogen addition in a semi‐intensive turbot larval aquaculture system: effects on phytoplankton and zooplankton composition

A nitrogen manipulation experiment was conducted in a semi‐intensive outdoor system where turbot larvae feed on copepods. Nitrogen addition is hypothesized to stimulate a cascade reaction increasing phytoplankton biomass, copepods’ productivity and larval fish survival. Triplicates were established for three treatments: a control with no additional nitrogen, a pulsed dose where nitrogen was added in three doses over time and a full dose where all nitrogen, equal to the total of the pulse dose treatment, was added initially. In the control, chlorophyll a averaged 3.3 ± 1.5 μg L^?1 and phytoplankton was dominated by diatoms, while the pulsed and full dose treatments showed chlorophyll a at 28.6 ± 9.9 and 47.7 ± 10.0 μg L^?1, respectively, with dinoflagellates as the main phytoplankton group. Due to photosynthesis, pH increased >9 in both the nitrogen treatments compared to the control (8.5). Potential toxic dinoflagellates, including Alexandrium pseudogonyaulax and Prorocentrum spp., became dominant in the nitrogen treatments and might have arrested zooplankton recruitment. Laboratory experiments with a toxic strain of A. pseudogonyaulax proved that Acartia tonsa reproduction and naupliar survival were affected negatively at realistic fish tank concentrations of 100 and 20 cells mL^?1, respectively. Compared to the control, pulsed and full dose treatments reached higher copepod biomass and showed a shift over time in species composition from Centropages hamatus to Acartia spp. However, high pH levels and dinoflagellate blooms had a negative effect on larval fish survival, suggesting management improvements on water quality and separation between copepods and fish production tanks.     

Does the capacity for energy utilization affect the survival of post‐smolt Atlantic salmon,Salmo salar L., during natural outbreaks of infectious pancreatic necrosis?

If osmotic stress and reduced seawater tolerance are predisposing factors for infectious pancreatic necrosis (IPN) outbreaks in farmed Atlantic salmon, increased survival by enhancing access to energy would be expected. The aim of the present study was, therefore, to increase energy access in 1-year old Atlantic salmon after sea transfer by increasing the level of dietary fat, by exchanging some of the dietary oil with more easily oxidized medium chain triacylglycerols, or by dietary supplementation of potentially energy enhancing additives such as clofibrate and tetradecylthioacetic acid (TTA). A natural outbreak of IPN occurred 8 weeks after sea transfer, and a significant dietary effect explaining 76% of the variation in mortality was observed. Relative percentage survival for the fish fed TTA in sea water was 70% when compared with the unsupplemented control, reducing mortality from 7.8 to 2.3%. Muscle fat content and plasma chloride were related to IPN mortality, suggesting that reduced hypoosmoregulatory capacity might be a predisposing factor to the onset of an IPN outbreak. Based on the observation of a threefold increase in white muscle mitochondrial fatty acid oxidizing activity by TTA, it is suggested that TTA has resulted in a re-allocation of dietary fatty acids from storage to energy producing oxidation.     

Growth performance,feed utilization and product quality in slaughter size Atlantic salmon (Salmo salar L.) fed a diet with porcine blood meal,poultry oil and salmon oil

In a 17‐week experiment with Atlantic salmon (2.3–5.2 kg) in sea cages, a diet containing European animal by‐products and salmon oil (ABP) was compared with a control diet based on fish and plant ingredients, with respect to performance and product quality. Fish fed with the ABP diet had similar growth rates, but slightly improved feed conversion ratio (feed: gain; 1.08 versus 1.14) compared with the control. No differences were seen in fish length, live weight or condition factor. Final body composition was similar and retention of nitrogen and energy did not differ between diets. Higher DPA (C22:5 n‐3) content in the ABP diet apparently inhibited conversion of EPA (C20:5 n‐3) to DPA, resulting in higher EPA retention in muscle and whole body. Muscle and whole body DHA (C22:6 n‐3) level and n‐3 : n‐6 ratio were higher in the ABP group, corresponding with dietary levels. There were no differences in slaughter yield, quality classification, gaping score or fillet texture between diets. The feed with ABP contained less astaxanthin, possibly because of degradation catalyzed by iron in blood meal, and this resulted in lower muscle colour score and astaxanthin concentration (4.6 versus 6.4 mg kg⁻¹). A sensory test did not reveal any differences in odour, flavour, or texture.     

Vitamin D status of 51-75-year-old Irish women: its determinants and impact on biochemical indices of bone turnover

OBJECTIVES: To assess the vitamin D status of Irish postmenopausal women during wintertime, and to examine its relationship with serum parathyroid hormone (PTH) and biochemical markers of bone turnover. In addition, the determinants of wintertime serum 25-hydroxyvitamin D (25OH-D) levels in these women were investigated. DESIGN: A cross-sectional observational study. SETTING: Cork City, Ireland (52 degrees N). SUBJECTS: Ninety-five apparently healthy, free-living postmenopausal women (aged 51-75 years), not taking any medication and free from any condition likely to affect vitamin D status or calcium/bone metabolism. RESULTS: Forty-eight per cent and 7% of women had serum 25OH-D levels <50 nmol l(-1) and <25 nmol l(-1), respectively. 25OH-D levels in these women were positively associated with dietary calcium intake (P = 0.0002) and use of vitamin D-containing supplements (P = 0.031), and negatively associated with cigarette smoking (P = 0.027) and body mass index (BMI) (P = 0.030). Low serum 25OH-D levels (<50 nmol l(-1)) were associated (P < 0.01) with elevated serum PTH levels. There were no significant differences in urinary pyridinium crosslinks or serum osteocalcin, biochemical indices of bone turnover, between subjects with serum 25OH-D levels above or below 50 nmol l(-1). CONCLUSION: A high proportion of Irish postmenopausal women had low vitamin D status (<50 nmol l(-1)) during late wintertime, which appeared to lead to elevated levels of serum PTH but not of bone turnover markers. Use of regular low-dose supplemental vitamin D, meeting daily calcium recommendations, cessation of smoking and maintaining BMI in the normal range are important factors that could help maintain adequate vitamin D levels during wintertime in these women.     

Failure to improve energy balance or dehydration by drenching transition cows with water and electrolytes at calving

The disease risk is very high among transition cows that may suffer from poor appetite. The aim of the present study was therefore to investigate the effect of drenching on energy balance, hydration state and selected production parameters in fresh cows. Twenty-one Danish Holstein-Friesian dairy cows in late pregnancy were randomly allocated to either treatment (TG) or control group (CG). TG cows were drenched twice with 20l of water containing a mixture of calcium propionate, MgSO₄, and KCL specifically developed for prophylactic treatment of fresh cows. The results indicated that cows become dehydrated around calving, losing on average 53l (TG) and 24.5l (CG) of extra-cellular fluid, respectively. The drenching volume applied in the present study did not affect the degree of hydration after calving. Based on blood NEFA and BHB values it was shown that drenching caused a reduction in the degree of negative energy balance (NEB). Somatic cell count (SCC) for cows in first lactation was lower in the TG compared to CG. Milk yield was unaffected by treatment. We conclude that prophylactic drenching added little to the health promotion in the transition cows in the present study. Instead, increased focus on management routines would probably be of more value.     

The effects of land tenure policy on rural livelihoods and food sufficiency in the upland village of Que,North Central Vietnam

The paper documents how the implementation of the land tenure policy of the Vietnamese government has affected the agricultural system, livelihood strategies and food self-sufficiency of Thai farmers in a remote upland village, Que, in Nghe An Province, North Central Vietnam. It is shown that the enforcement of restrictions on the area under swidden agriculture has resulted in a strong reduction of swidden agriculture production and shortened fallow periods, not compensated for by the slow increase in paddy rice production. It is suggested that while the changes imposed on land use certainly lead to an increase in forest cover, it is likely that the shortened fallow cycle on the land allocated to swiddening will lead to declining yields and replacement of forest fallow by bush and grass fallow, and thus to decreases in labour productivity. It is discussed whether there are options open to farmers for changing their portfolio of income generating activities in order to maintain and improve food self-sufficiency, income and living conditions. Finally, new trends in Vietnamese land tenure policy are outlined, and their possible implications discussed.     

Influence of biopores on root growth,water uptake and grain yield of wheat (Triticum aestivum) based on predictions from a computer model

Summary The use of vertical biopores by wheat (Triticum aestivum) seminal roots for easy access to the subsoil and the consequences for plant water supply and yield has been investigated by computer simulation. Parameters included were: biopore density and diameter, depth of cultivation and strength of the subsoil — all under a wide range of seasonal weather conditions. The model predicts that biopores add significantly to root penetration at depth, even at a density of 0.1% v/v of small, vertical pores, while 1.5% to 2.0% v/v can ensure maximum root penetration. When the growing season is shorter a larger number of biopores is needed to ensure timely root penetration to depth. With shallow tillage, biopores occur closer to the soil surface, and their importance is increased. Deeper root penetration invariably gives greater water uptake and transpiration, but may have a negative effect on grain yield, especially under the driest climatic conditions. An increase in early water use may result in less soil water being available during the grain-filling period. The effect of biopores on plant transpiration varies from year to year, depending on the amount of rain and its distribution in time, and on the amount of soil water stored at time of sowing.