Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Dietary nutrient composition affects digestible energy utilisation for growth: a study on Nile tilapia (Oreochromis niloticus) and a literature comparison across fish species
    Schrama, J.W. ; Subramanian, S. ; Geurden, I. ; Heinsbroek, L.T.N. ; Kaushik, S.J. ; Verreth, J.A.J. - \ 2012
    The British journal of nutrition 108 (2012)2. - ISSN 0007-1145 - p. 277 - 289.
    trout oncorhynchus-mykiss - ctenopharyngodon-idella val - bass dicentrarchus-labrax - rainbow-trout - feeding level - utilization efficiency - anguilla-anguilla - european eel - growing pigs - grass carp
    The effect of the type of non-protein energy (NPE) on energy utilisation in Nile tilapia was studied, focusing on digestible energy utilisation for growth (kgDE). Furthermore, literature data on kgDE across fish species were analysed in order to evaluate the effect of dietary macronutrient composition. A total of twelve groups of fish were assigned in a 2 × 2 factorial design: two diets (‘fat’ v. ‘starch’) and two feeding levels (‘low’ v. ‘high’). In the ‘fat’-diet, 125 g fish oil and in the ‘starch’-diet 300 g maize starch were added to 875 g of an identical basal mixture. Fish were fed restrictively one of two ration levels (‘low’ or ‘high’) for estimating kgDE. Nutrient digestibility, N and energy balances were measured. For estimating kgDE, data of the present study were combined with previous data of Nile tilapia fed similar diets to satiation. The type of NPE affected kgDE (0·561 and 0·663 with the ‘starch’ and ‘fat’-diets, respectively; P <0·001). Across fish species, literature values of kgDE range from 0·31 to 0·82. Variability in kgDE was related to dietary macronutrient composition, the trophic level of the fish species and the composition of growth (fat:protein gain ratio). The across-species comparison suggested that the relationships of kgDE with trophic level and with growth composition were predominantly induced by dietary macronutrient composition. Reported kgDE values increased linearly with increasing dietary fat content and decreasing dietary carbohydrate content. In contrast, kgDE related curvilinearly to dietary crude protein content. In conclusion, energy utilisation for growth is influenced by dietary macronutrient composition.
    Should Weaning be the Start of the Reproductive Cycle in Hyper-prolific Sows? A Physiological View
    Kemp, B. ; Soede, N.M. - \ 2012
    Reproduction in Domestic Animals 47 (2012)Suppl. 4. - ISSN 0936-6768 - p. 320 - 326.
    lactating primiparous sows - to-estrus interval - litter size - follicular development - feeding level - altrenogest treatments - progestagen treatment - endocrine changes - embryo survival - 1st-litter sows
    Normally, sows are in anoestrus during lactation and start their new cycle at the day of weaning. Modern hybrid primiparous sows that suckle large numbers of piglets may lose substantial amounts of body reserves during lactation. This compromises follicle development during lactation. As modern sows have short weaning-to-oestrus intervals, these compromised follicles are recruited for ovulation directly after weaning, resulting in lower ovulation rates and lower embryo survival. Postponing or skipping first oestrus after weaning in primiparous sows may help to limit the negative consequences of lactation on subsequent reproduction. Multiparous sows may have very high litter sizes, especially after long lactations as applied in organic sows. These high litter sizes compromise piglet birthweight and survival and subsequent performance. Inducing lactation oestrus in multiparous sows may help to limit litter size and improve piglet survival and performance. This study discusses physiological and reproductive effects of extending the start of a new pregnancy after lactation in primiparous sows and induction of lactation oestrus in multiparous sows. We thereby challenge the view that weaning is an ideal start for the reproductive cycle in modern sows.
    LH and FSH secretion, follicle development and oestradiol in sows ovulating or failing to ovulate in an intermittent suckling regimen
    Langendijk, P. ; Dieleman, S.J. ; Dooremalen, C. van; Foxcroft, G.R. ; Gerritsen, R. ; Hazeleger, W. ; Soede, N.M. ; Kemp, B. - \ 2009
    Reproduction Fertility and Development 21 (2009)2. - ISSN 1031-3613 - p. 313 - 322.
    luteinizing-hormone - primiparous sows - stimulating-hormone - lactating sows - litter separation - boar exposure - feeding level - estrus - expression - prolactin
    The present paper describes LH and FSH secretion, follicle development and ovulation in sows that were subjected to a limited nursing regimen. From Day 14 of lactation, 32 sows were separated from their piglets for 12 h every day (intermittent suckling; IS). Half the sows had boar contact during separation. Nine of 32 sows ovulated spontaneously within 14 days from initiation of IS. The frequency of LH pulses on the first day of IS tended to be higher in anovulatory sows (6.3 v. 4.2 pulses per 12 h; P <0.10); other characteristics of LH secretion were similar to sows that ovulated. The characteristics of FSH secretion did not differ over the 8-h sampling period. Boar contact did not influence either LH and FSH secretion or the number of sows that ovulated. Up to 58% of anovulatory sows showed an increase in follicle size after initiation of IS and, 4 days after the initiation of IS, one-third still had follicles similar in size to those in ovulatory sows. However, the oestradiol concentration in anovulatory sows did not increase. We conclude that FSH and LH stimulation in anovulatory sows is not limiting for normal follicle development, but that ovarian follicles are not responsive to increased LH secretion
    Whole body and muscle energy metabolism in preruminant calves: effects of nutrient synchrony and physical activity
    Borne, J.J.G.C. van den; Hocquette, J.F. ; Verstegen, M.W.A. ; Gerrits, W.J.J. - \ 2007
    The British journal of nutrition 97 (2007)4. - ISSN 0007-1145 - p. 667 - 675.
    skeletal-muscle - feeding level - growing pigs - fiber characteristics - palmitate oxidation - adipose-tissue - milk replacer - meat quality - amino-acid - protein
    The effects of asynchronous availability of amino acids and glucose on muscle composition and enzyme activities in skeletal muscle were studied in preruminant calves. It was hypothesized that decreased oxidative enzyme activities in muscle would explain a decreased whole body heat production with decreasing nutrient synchrony. Preruminant calves were assigned to one of six degrees of nutrient synchrony, step-wise separating the intake of protein and lactose over the two daily meals. Calves at the most synchronous treatment received two identical meals daily. At the most asynchronous treatment, 85 % of the daily protein and 20 % of the daily lactose supply were fed in one meal and the remainder in the other meal. Daily intakes of all dietary ingredients were identical for all treatments. Oxidative enzyme activities and fat content increased with decreasing nutrient synchrony in M. Rectus Abdominis (RA), but not in M. Semitendinosus. Cytochrome-c-oxidase activity was positively correlated with fat content in RA (r 0·49; P <0·01). Oxidative enzyme activities in both muscles were not correlated with average daily heat production, but citrate synthase activity in RA was positively correlated (P <0·01) with the circadian amplitude (r 0·53) and maximum (r 0·61) of heat production associated with physical activity. In conclusion, this study indicates that muscle energy stores are regulated by nutrient synchrony. The lack of correlation between muscle oxidative enzyme activities and average daily heat production was in contrast with findings in human subjects. Therefore, oxidative enzyme activity in muscle should not be used as an indicator for whole body heat production in growing calves.
    Modelling of nutrient partitioning in growing pigs to predict their anatomical body composition. 1. Model description
    Halas, V. ; Dijkstra, J. ; Babinszky, L. ; Verstegen, M.W.A. ; Gerrits, W.J.J. - \ 2004
    The British journal of nutrition 92 (2004)4. - ISSN 0007-1145 - p. 707 - 723.
    muscle protein-turnover - finishing gilts 45 - energy-intake - lipid accretion - chemical-composition - fattening pigs - feeding level - kg liveweight - earlier life - 85 kilograms
    A dynamic mechanistic model was developed for growing and fattening pigs. The aim of the model was to predict growth rate and the chemical and anatomical body compositions from the digestible nutrient intake of gilts (20-105 kg live weight). The model represents the partitioning of digestible nutrients from intake through intermediary metabolism to body protein and body fat. State variables of the model were lysine, acetyl-CoA equivalents, glucose, volatile fatty acids and fatty acids as metabolite pools, and protein in muscle, hide-backfat, bone and viscera and body fat as body constituent pools. It was assumed that fluxes of metabolites follow saturation kinetics depending on metabolite concentrations. In the model, protein deposition rate depended on the availability of lysine and of acetyl-CoA. The anatomical body composition in terms of muscle, organs, hide-backfat and bone was predicted from the chemical body composition and accretion using allometric relationships. Partitioning of protein, fat, water and ash in muscle, organs, hide-backfat and bone fractions were driven by the rates of muscle protein and body fat deposition. Model parameters were adjusted to obtain a good fit of the experimental data from literature. Differential equations were solved numerically for a given set of initial conditions and parameter values. In the present paper, the model is presented, including its parameterisation. The evaluation of the model is described in a companion paper.
    Leptin concentrations in relation to energy balance, milk yield, intake, live weight and estrus in dairy cows
    Liefers, S.C. ; Veerkamp, R.F. ; Pas, M.F.W. te; Delavaud, C. ; Chilliard, Y. ; Lende, T. van der - \ 2003
    Journal of Dairy Science 86 (2003). - ISSN 0022-0302 - p. 799 - 807.
    adipose-tissue - plasma leptin - luteinizing-hormone - circulating leptin - growth-hormone - feeding level - female mice - sheep - pregnancy - postpartum
    The objective of this study was to describe fluctuations in leptin concentrations during late pregnancy and lactation and to investigate how those fluctuations are related to energy balance, milk yield, milk components, dry matter intake, live weight, first postpartum luteal activity, and first observed estrus during lactation. Live weight, dry matter intake, energy balance, and milk yield were measured weekly on 304 primiparous Holstein cows for the first 80 d of lactation. The first postpartum luteal activity was determined by measuring milk progesterone, and independently, first observed estrus. For measuring leptin concentrations from 30 d before until 80 d after calving, blood samples were taken at 2-wk intervals at a fixed time of the day after milking but before feeding. Leptin concentrations were high during pregnancy and declined to a nadir at parturition. It seems that leptin concentrations reflect the state of energy balance during lactation; plasma leptin concentrations were lower in cows with a mean negative energy balance during lactation. Those cows usually produced more milk, consumed less feed, and had a lower live weight compared with cows having a mean positive energy balance. The recovery of leptin concentrations from the leptin nadir at parturition seemed to depend on the extent and duration of the negative energy balance, thus probably on the amount of fat that was re-accumulated. Although there was lack of a relationship between leptin and first postpartum luteal activity, higher leptin concentrations associated with shorter intervals to first observed estrus might indicate a relationship between leptin and expression of estrus.
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