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Manure nitrogen (N) from cattle contributes to nitrous oxide and ammonia emissions and nitrate leaching. Measurement of manure N outputs on dairy farms is laborious, expensive, and impractical at large scales; therefore, models are needed to predict N excreted in urine and feces. Building robust prediction models requires extensive data from animals under different management systems worldwide. Thus, the study objectives were (1) to collate an international database of N excretion in feces and urine based on individual lactating dairy cow data from different continents; (2) to determine the suitability of key variables for predicting fecal, urinary, and total manure N excretion; and (3) to develop robust and reliable N excretion prediction models based on individual data from lactating dairy cows consuming various diets. A raw data set was created based on 5,483 individual cow observations, with 5,420 fecal N excretion and 3,621 urine N excretion measurements collected from 162 in vivo experiments conducted by 22 research institutes mostly located in Europe (n = 14) and North America (n = 5). A sequential approach was taken in developing models with increasing complexity by incrementally adding variables that had a significant individual effect on fecal, urinary, or total manure N excretion. Nitrogen excretion was predicted by fitting linear mixed models including experiment as a random effect. Simple models requiring dry matter intake (DMI) or N intake performed better for predicting fecal N excretion than simple models using diet nutrient composition or milk performance parameters. Simple models based on N intake performed better for urinary and total manure N excretion than those based on DMI, but simple models using milk urea N (MUN) and N intake performed even better for urinary N excretion. The full model predicting fecal N excretion had similar performance to simple models based on DMI but included several independent variables (DMI, diet crude protein content, diet neutral detergent fiber content, milk protein), depending on the location, and had root mean square prediction errors as a fraction of the observed mean values of 19.1% for intercontinental, 19.8% for European, and 17.7% for North American data sets. Complex total manure N excretion models based on N intake and MUN led to prediction errors of about 13.0% to 14.0%, which were comparable to models based on N intake alone. Intercepts and slopes of variables in optimal prediction equations developed on intercontinental, European, and North American bases differed from each other, and therefore region-specific models are preferred to predict N excretion. In conclusion, region-specific models that include information on DMI or N intake and MUN are required for good prediction of fecal, urinary, and total manure N excretion. In absence of intake data, region-specific complex equations using easily and routinely measured variables to predict fecal, urinary, or total manure N excretion may be used, but these equations have lower performance than equations based on intake., This study is part of the Global Network project, funded by the Joint Programming Initiative on Agriculture, Food Security and Climate Change (FACCE-JPI) and is an activity of the Feed and Nutrition Network, which is part of the Livestock Research Group of the Global Research Alliance for Agricultural Greenhouse Gases (https://globalresearchalliance.org; accessed May 10, 2021). Partial funding for the study was provided through USDA (Washington, DC) National Institute of Food and Agriculture (NIFA), awards 2014-67003-21979 and 2019-67019-29400, and Federal Appropriations under Project PEN 04539 and Accession Number 1000803 and FONDECYT/Regular Accession Number 1191476.

An inquiry was carried out to assess the concentrations of plasma metabolites related to bone remodelling in 21 saddle horses of Warmblood breed aged 4-26 years, five draught horses of Ardennes breed aged 4-10 years, and 10 Ardennes foals aged 9-11 months. They were fed according to normal feeding practice in Belgium. The changes in some bone remodelling plasma metabolite concentrations were studied when an unbalanced diet was offered and later corrected for four Warmblood horses. Bone formation was evaluated by bone alkaline phosphatase (BALP), total alkaline phosphatase (TALP) and osteocalcin (bone gla-protein, OC). Bone resorption was assessed by hydroxyproline (HYP). Total calcium, ionized calcium, phosphorus (P) and 25-hydroxyvitamin D3 [25-(OH)D] concentrations were more or less constant. The comparison of four bone remodelling factors between the Ardennes and Warmblood horses showed higher concentrations in the Ardennes breed. Bone marker concentrations decreased according to age. The correction of the unbalanced Ca : P diet induced inconsistent effects at plasma level. The interpretation of the different bone parameters appeared to be difficult if not associated with other parameters such as a complete anamnesis and clinical examination of the animal in addition to dietary evaluation.

Antioxidant mechanisms, immune responses, reproduction, thyroid metabolism are processes in which the trace element selenium (Se) is involved. In beef production with suckling herds, a Se deficiency could impair animal health resulting in reduced incomes. In Belgium the Se content in locally produced feedstuffs is low and thus, in beef farms where locally produced feedstuffs are fed for the entire year, symptoms of Se deficiency are observed. The aim of the present study was to assess the effect, of Se enriched fertilizers on the Se content of feedstuffs and on the Se status of cattle.

Performances traits like live weight gain, feed conversion ratio or carcass quality were in the past the main objectives in beef meat production. Nowadays consumers attach an increasingly large importance to technological and nutritional qualities. In terms of dietetic, a low fat content associated with a high polyunsaturated fatty acids content and a low n-6/n-3 ratio is required. In this context, the present work was undertaken to compare performances and meat characteristics in young fattening bulls of 3 beef breeds offered 2 different diets.

Lucerne and chalk are sources of calcium used to supplement horses diets. The voluntary ingestion of lucerne varies with its form (Cuddeford, 1994). The objectives of this study were to compare the appetency for different sources of calcium, measured by kinetic of ingestion and selection behaviour (sorting, refusal) and to evaluate the effect of those different sources of calcium supplements on the preference of diets offered as a simultaneous choice. The sources of calcium studied were chalk and dehydrated lucerne presented in three forms: 6 mm diameter pellets, 18 mm diameter pellets and ground.

When horses are on diets that are predominant in cereals, the combination of low concentrations of calcium in the diet and the binding of calcium by phytates may result in inadequate calcium intake (Rose, 1990). Chalk and dehydrated lucerne are rich in calcium. It has been shown that the voluntary ingestion of lucerne varies with its form (Cuddeford, 1994). The aim of this study was to evaluate the effect of different sources of calcium (chalk vs dehydrated lucerne) and lucerne forms (6 mm diameter pellets, 18 mm diameter pellets and ground lucerne) on the ingestion and on the metabolic profile in horses offered a cereal-based diet.

Fat supplementation is commonly used in feedstufs for high yielding cows or ewes. The diet for growing-fattening bulls in Belgium are usually high in concentrate. The fat content.of such diets .is low at .about 2.51. Over the recent years, feed manufacturers have incorporated fat in diets for growing-fattening animals (Clmquart, Istasse, Dufrasne, Mayombo, Van Eenaeme, Bienfait, 1991). In most of the reported works the fat supplemented diets were offered during the whole fattening period according to Brandt, Anderson and Elliot (1988) and Zinn (1989), differences in performance could be expected when the fat supplement is offered only during the finishing period. An experimental was designed to compare the effects of fat supplementation during the last part of the fattening period on the performance and meat characteristics of fattening bulls.

The Holstein and Belgian Blue double muscle type (BBDM) are two cattle breeds extremely different in extent of muscle proportion (Istasse, Van Eenaeme, Evrard, Gabriel, Baldwin, Maghuin-Rogister and Bienfait, 1990). In BBDM, the proportions of lean meat and fat are high and low respectively. Opposite trends are found in Holstein, the Belgian Blue dual purpose type (BBDP) being intermediate. This experiment was carried out to compare lipid metabolism in these 3 breeds.Four bulls of these 3 breeds were used in a fattening trial. The initial weight was 340 kg. They were given a sugar beet pulp based diet supplemented with cereals, by-products and protein sources or vegetable origin. After a 145 days fattening period the final weight was 540 kg. Non esterified fatty acid (NEFA), triglycerides (TG) and cholesterol concentrations in the plasma were measured every 4 weeks during the fattening period. The plasma fatty acid composition was determined by gas chromatography. The 7, 8 and 9 ribs were removed at slaughter and cholesterol concentrations were measured in Longissimus Dorsi samples.

Growing fattening bulls in Belgium require diets high in concentrate and low in roughages in order to achieve large live weight gains and high quality carcasses. Sugar beet pulp is usually incorporated at a high inclusion rate in fattening diets. It is supplemented with cereals, by-products like wheat bran or glutenfeed and protein supplements very often of vegetable origin. The fat content of such diet is low. Over the recent years, there has been an increasing pressure from the industry to incorporate fat in fattening diets. Each company produces its own fat concentrate. They are blends of various origins. The present experiments were carried out to assess the effects, on animal performances, of soya oil and linseed, two fat concentrates of vegetable origin incorporated in fattening diets.