Gerhard Bellof

(13)C discrimination between diet, faeces, milk and milk components.

Stable isotope analysis is a fundamental tool in food origin and authenticity testing. Its use in livestock production requires knowledge of isotope discrimination between product and diet. Here, we report 13C discrimination (13Δ) for milk, milk components (fat, casein and lactose) and faeces in eight lactating dairy cows, which grazed pasture or were fed fresh pasture herbage in the stall. Cows were supplemented with grain maize at 1.72 kg d−1 (dry matter). Feed components were collected daily, and faeces, milk fat, casein, lactose and whole milk 4 times per week during an 8-week-long sampling period. Carbon isotope composition (δ13C) of each sample was analysed. δ13C was lowest in milk fat (−29.8 ‰) and highest in casein (−26.4 ‰). Compared to the diet, whole milk was depleted in 13C (13Δ = 0.4 ‰) due to a strong 13C-depletion of fat (13Δ = 2.2 ‰), which was not fully compensated by the 13C-enrichment of casein (13Δ = −1.1 ‰) and lactose (13Δ = −0.7 ‰). Faeces were also depleted in 13C (13Δ =1.7 ‰). Influences of feeding environment (stall vs. pasture) and herbage quality were minor (<0.4 ‰). A review of literature data shows large variation between studies. We consider that the present results are superior, as they are based on a much larger data set regarding the number of cows and milkings (total n = 256) with greater detail in analyses of diet and milk products. Also, the study covered both stall- and pasture-feeding scenarios in realistic settings with long periods of equilibration. This is the first comprehensive analysis of 13C discrimination between diet and all main milk components (as well as faeces). Thus, the results will improve the use of stable isotope analyses in regard to authenticity testing and proof of origin.

Forward Modeling of Fluctuating Dietary 13C Signals to Validate 13C Turnover Models of Milk and Milk Components from a Diet-Switch Experiment

Isotopic variation of food stuffs propagates through trophic systems. But, this variation is dampened in each trophic step, due to buffering effects of metabolic and storage pools. Thus, understanding of isotopic variation in trophic systems requires knowledge of isotopic turnover. In animals, turnover is usually quantified in diet-switch experiments in controlled conditions. Such experiments usually involve changes in diet chemical composition, which may affect turnover. Furthermore, it is uncertain if diet-switch based turnover models are applicable under conditions with randomly fluctuating dietary input signals. Here, we investigate if turnover information derived from diet-switch experiments with dairy cows can predict the isotopic composition of metabolic products (milk, milk components and feces) under natural fluctuations of dietary isotope and chemical composition. First, a diet-switch from a C3-grass/maize diet to a pure C3-grass diet was used to quantify carbon turnover in whole milk, lactose, casein, milk fat and feces. Data were analyzed with a compartmental mixed effects model, which allowed for multiple pools and intra-population variability, and included a delay between feed ingestion and first tracer appearance in outputs. The delay for milk components and whole milk was ∼12 h, and that of feces ∼20 h. The half-life (t½) for carbon in the feces was 9 h, while lactose, casein and milk fat had a t½ of 10, 18 and 19 h. The 13C kinetics of whole milk revealed two pools, a fast pool with a t½ of 10 h (likely representing lactose), and a slower pool with a t½ of 21 h (likely including casein and milk fat). The diet-switch based turnover information provided a precise prediction (RMSE ∼0.2 ‰) of the natural 13C fluctuations in outputs during a 30 days-long period when cows ingested a pure C3 grass with naturally fluctuating isotope composition.

Routing of Fatty Acids from Fresh Grass to Milk Restricts the Validation of Feeding Information Obtained by Measuring 13C in Milk

Dairy production systems vary widely in their feeding and livestock-keeping regimens. Both are well-known to affect milk quality and consumer perceptions. Stable isotope analysis has been suggested as an easy-to-apply tool to validate a claimed feeding regimen. Although it is unambiguous that feeding influences the carbon isotope composition (δ(13)C) in milk, it is not clear whether a reported feeding regimen can be verified by measuring δ(13)C in milk without sampling and analyzing the feed. We obtained 671 milk samples from 40 farms distributed over Central Europe to measure δ(13)C and fatty acid composition. Feeding protocols by the farmers in combination with a model based on δ(13)C feed values from the literature were used to predict δ(13)C in feed and subsequently in milk. The model considered dietary contributions of C3 and C4 plants, contribution of concentrates, altitude, seasonal variation in (12/13)CO2, Suesss effect, and diet-milk discrimination. Predicted and measured δ(13)C in milk correlated closely (r(2) = 0.93). Analyzing milk for δ(13)C allowed validation of a reported C4 component with an error of <8% in 95% of all cases. This included the error of the method (measurement and prediction) and the error of the feeding information. However, the error was not random but varied seasonally and correlated with the seasonal variation in long-chain fatty acids. This indicated a bypass of long-chain fatty acids from fresh grass to milk.

The effects of breed, grazing system and concentrate supplementation on the fatty acid profile of the musculus longissimus dorsi and the kidney fat of steers

Abstract. The study is aimed at determining the effect of breed (German Simmental vs. German Holstein), grazing system (continuous grazing system [CGS] vs. rotational grazing system [RGS]) and concentrate supplementation (level and type of concentrate) on the fatty acid profile of longissimus muscle and kidney fat of steers. The trial involved four phases: in P1 all animals remained indoors; in P2 and P4 they were allocated on CGS or RGS; during P3 one group remained outdoors, the other indoors. In P1 and P3 the steers were offered grass silage and concentrate. In P3 the indoors group received a supplement with a medium or low-concentrate level. For the last 28 days of P4 the steers were offered a concentrate type with 4.9 % linseed oil or with 1.0 % rapeseed oil. CGS-pasture resulted in higher fatty acid values than RGS-pasture; linseed-oil concentrate resulted in higher ALA, Σn-3 and lower LA, Σn-6 than rapeseed-oil concentrate. German Simmental breed had lower IMF-content and higher Σn-3, Σn-6, n-6/n-3 ratio and PUFA/SFA ratio in longissimus dorsi and kidney fat than German Holstein breed. The proportion of CLA was higher in German Holstein breed than in German Simmental breed (0.56 vs. 0.50 g/100 g FAME). RGS group showed lower ALA and higher n-6/n-3 in longissimus dorsi and kidney fat than CGS-group. Neither the level nor the type of concentrate affected the LD and kidney fat fatty acids. Healthy fatty acids levels were higher in the German Holstein breed meat. The CGS-group meat had higher contents of ALA and EPA. However, the legal requirements for human nutrition and other health related claims could not be met.

Utilization of energy for growth in lambs of the breed german merino landsheep

Based on energy deposition and energy intake the utilization of energy for fat and protein deposition and the mean energy utilization for growth as well as the energy requirement for maintenance were estimated in this study. Fifty-four male and 54 female lambs were fed at three feeding levels and slaughtered at various body weights (BW): 18, 30, 45, and 55 kg. Based on the method of the comparative slaughter technique the total body of each animal was analysed. From the data of empty-body gain, fat, protein and energy deposition in the different fattening periods was calculated. The utilization of metabolizable energy for growth and maintenance was estimated by a multiple linear regression model. In this regression model, a utilization of energy for fat deposition of 71% and for protein deposition of 30% was determined (R2 = 0.869). The requirement for maintenance was 520 kJ·kg BW − 0.75·d − 1. A slightly higher requirement for maintenance was determined for female lambs. The study indicated that the used regression model can be recommended to estimate the utilization of energy and the requirement for maintenance in growing lambs.

The effect of high or low content of glucosinolates in rapeseed cake used for concentrate mixtures in lamb fattening

In a feeding trial with lambs the following aspects were investigated: 1. The effect of increased contents of rapeseed cake in diets used for lamb fattening on feed intake, fattening and carcass yield. 2. The effect of increased glucosinolate content in diets, with regard to the aspects mentioned above to the weight of thyreoid gland and to the content of bilirubin in blood plasma. In total forty weaned tup lambs (genotype: Merino Sheep) were fattened to an average finishing weight of 45 kg. The sheep were fed ad libitum with a concentrate mixture and hay (high feeding intensity). Four groups of ten lambs each received four different mixed concentrates on the basis of coarse meal of cereal-dried sugar beet pulp-soybean. The mixtures contained 14% resp. 24% rapeseed cake of quality A and B, respectively. These two rapeseed cakes differed in the content of glucosinolates (A: 8.0 mMol/kg; B: 26.5 mMol/kg). In conclusion the four concentrate mixtures contained different contents of glucosinolates (analysed in confirming of EU method): testgroup 1 (14% rapeseed cake A): 1.0 mMol/kg; testgroup 2 (14% rapeseed cake B): 2.7 mMol/kg; testgroup 3 (24% rapeseed cake A): 1.3 mMol/kg; testgroup 4 (24% rapeseed cake B): 4.7 mMol/kg. The calculated GSL contents were remarkably higher than the analysed ones. All mixtures were composed approximately isoenergetically and isonitrogenously. All four feed compounds were fed without problems of acceptance. Between the groups there were only negligible differences in the average daily feed intake and fattening yield. The average daily gain was 354 g. Comparing the four groups, there were only small differences in carcass yield, weight of thyreoid gland and content of bilirubin in blood plasma. The animals with higher intake of glucosinolates (testgroups 2 and 4) had a slightly lower content of bilirubin. It is possible to use pelleted mixtures, which contained up to 24% rapeseed cake, for fattening of lambs. Zum Einsatz von Rapskuchen mit hohen oder niedrigen Glucosinolatgehalten in Futtermischungen fur Mastlammer 1. Wie wirken sich steigende Rapskuchenanteile in Lammermastmischungen auf den Kraftfutterverzehr, die Mastleistung und die Schlachtleistung der Tiere aus? 2. Welchen Einflus hat eine erhohte Glucosinolataufnahme auf die genannten Merkmale sowie den Plasmabilirubingehalt und die Schilddrusengewichte? Insgesamt vierzig abgesetzte Bocklammer (genetische Herkunft: Merino-Landschaf) wurden unter den Bedingungen einer hohen Futterungsintensitat (Kraftfutter ad libitum) bis zu einem mittleren Endgewicht von ca. 45 kg gemastet. In vier Gruppen (n = 10) wurden vier verschiedene Kraftfuttermischungen – auf der Basis Getreide-Trockenschnitzel-Sojaextraktionsschrot – eingesetzt. In die Mischungen wurden 14% bzw. 24% Rapskuchen der Qualitaten A bzw. B eingemischt. Rapskuchen A wies einen Glucosinolatgehalt (GSL) von 8 mMol/kg auf, Rapskuchen B von 26,5 mMol/kg. Somit enthielten die vier Versuchsmischungen unterschiedliche GSL-Gehalte (Analyse nach EU-Methodenvorschrift): Versuch 1 (14% Rapskuchen A): 1,0 mMol/kg; Versuch 2(14% Rapskuchen B): 2,7 mMol/kg; Versuch 3 (24% Rapskuchen A): 1,3 mMol/kg; Versuch 4 (24% Rapskuchen B): 4,7 mMol/kg. Die berechneten GSL-Gehalte der Futtermischungen lagen deutlich uber den analysierten Werten. Die Mischungen waren nahezu isoenergetisch und isonitrogen zusammengesetzt. Alle vier Futtermischungen wurden ohne Akzeptanzprobleme verzehrt. Hinsichtlich des durchschnittlichen Futterverzehrs und der Mastleistung unterschieden sich die Gruppen nur geringfugig. Im Durchschnitt erreichten die Lammer Tageszunahmen in Hohe von 354 g. Auch bei den Schlachtleistungsmerkmalen, den Bilirubinwerten und den Schilddrusengewichten traten nur geringe Gruppenunterschiede auf. Die Tiere mit erhohter Glucosinolataufnahme (Versuch 2 und Versuch 4) wiesen leicht erniedrigte Bilirubingehalte im Plasma auf. In pelletierten Kraftfuttermischungen fur die Lammermast konnen Mischungsanteile von bis zu 24% Rapskuchen ohne Leistungseinbusen eingesetzt werden. The effect of high or low content of glucosinolates in rapeseed cake used for concentrate mixtures in lamb fattening

Accidental finding of Hashimoto-like thyroiditis in male B.U.T. 6 turkeys at slaughter

In the context of a study on the tolerance of rapeseed meal in B.U.T. 6 turkeys, thyroid glands were histologically and immunohistochemically examined because of potential thyreostatic effects. In all groups including the controls with no rapeseed meal in their food, there was a high incidence of lymphocytic infiltration and thyroiditis (14% of thyroids with moderate to severe lymphocytic thyroiditis). Thirty per cent of mononuclear inflammatory cells were immunohistochemically identified as T cells. There were occasional accumulations of PAX-5 labelled cells, indicating germinal centre development. These lesions resemble Hashimotos disease in humans. The effect on thyroid function is unknown. Mild hypothyreosis might enhance productivity but also explain dispositions towards diseases seen in context with thyroid dysfunction such as skin diseases (foot pad disease?) and cardiovascular problems. Further studies on thyroid function in these turkeys are needed.

How does feeding organic broilers high levels of alfalfa silage affect the meat quality

The aim of the study was to evaluate the effect of young harvested alfalfa silage as a protein source in the diet of organic broilers on the meat quality. Four groups were formed: In control group A, animals received a complete feed mixture (CFM); in the next three groups, animals received a supplemental feed mixture (SFM) and alfalfa silage as chopped (group B), extruded (group C) and pelleted (group D). Alfalfa meal (12%) was integrated into the CFM and rapeseed oil into the SFM (3.75%) and also into the pellets (3%). The broilers consumed up to 30% of silage of their daily dry matter intake. Silage improved the proportion of polyunsaturated fatty acids, mainly n-3. High levels of silage consumption and consequently high ratios of alfalfa/fat in the diets of groups B and C were related to the low content of cholesterol in the meat. Sensory characteristics were not affected and sensory abnormalities were not detected. Alfalfa silage altered the meat colour; however, the yellow intensity (b*) depended on the ratio of fat/silage of the diet. Group D showed the lowest silage intake but the highest b* due to the highest fat/silage ratio of the diets. The applied processes (chopping, extrusion or pelletisation) for the obtainment of silage had no effect on the quality of the meat. The production of organic meat with the mentioned positive characteristics using alfalfa silage for the market is possible.