Effect of graded levels of rare earth elements in diets of fattening bulls on growing and slaughtering performance, and on nutrient digestibility of wethers

Abstract

The aim of the present dose response study was to examine the long-term effects of increasing the amounts of rare earth elements (REE) in the diet on growth and slaughtering performance of fattening bulls. A total of 48 bulls of German Holstein with an average initial live weight (LW) of 119 + 13 kg were divided into four dietary treatment groups (n = 12): a control group and three REE-treated groups, which were fed a supplement of 100, 200 and 300 mg REE-citrate per kg dry matter (DM) containing mainly cerium (57.9%), lanthanum (34.0%) and praseodymium (6.5%). The feeding trial was divided into a growing period for 8 weeks and a fattening period for 39 weeks. The growing diet consisted of concentrate, grass silage and grass hay, while the fattening diet consisted of concentrate and maize silage. The animals were slaughtered at approximately 556 kg LW. The intake of grass hay and maize silage (0.55-0.31 kg/d and 6.09-5.44 kg/d, respectively) decreased linearly (p < 0.05) with increasing REE-citrate supplementation, while LW gain showed only a numerical decrease during the growing (2-4%) and the fattening period (4-5%). The feed-to-gain ratio and ME-to-gain ratio were not significantly affected by REE treatment during the whole feeding trial. The most striking effect of REE on carcass characteristics was a significantly higher dressing percentage in Group C (200 mg REE citrate kg/DM) compared to the other groups, while no effects were found on liver, kidneys, heart, thymus, pancreas, spleen and thyroid gland weights. The digestibility trials with wethers indicate that a supplementation of 300 mg REE-citrate per kg DM to a ration consisting of concentrate and straw does not enhance the digestibility of nutrients. These results suggest that, under the conditions of the present study, the supplementation of fattening bull diets with REE cannot be recommended.

Effect of Rare Earth Elements on Feed Digestibility, Rumen Fermentation, and Purine Derivatives in Sheep

“…The quadratic response to REE addition indicated that 300 mg/kg DM did not increase nutrient digestibility in the total tract and in situ ruminal ED of Leymus chinensis aNDF. This observation was in accordance with Schwabe et al (2011), who observed no significant influence on digestibility of nutrients by addition of 300 mg/kg DM REE.…”

Rare earth elements and relation between their potential bioavailability and soil properties, Nidda catchment (Central Germany)

“…Apart from the intense industrial use, REEs are applied in Chinese agriculture for over four decades. Positive effects in plant production and animal husbandry have been documented (He et al 2001;Schwabe et al 2011;Hu et al 2004). Hu et al (2006) summarized that in China in 2001 6.5 million ha of land were treated with 11,000 t of REEs by direct application of microelement fertilizers.…”

Effects of supplementing rare earth element cerium on rumen fermentation, nutrient digestibility, nitrogen balance and plasma biochemical parameters in beef cattle

“…The reason for the differences in the results between different trials could be that the REE levels used in the trials of Schwabe et al. () were lower than in other trials. The results indicated that the effects of REE on increasing nutrient digestibility could be dose dependent.…”

“…Schwabe et al. (), however, reported that supplementing up to 300 mg REE citrate/kg DM to the rations of growing and fattening cattle, consisting of 25.3% REE or 38.7% REE, respectively (REE composition: 57.9% Ce, 34.0% La, 6.5% Pr and 1.6% other REE), did not affect the digestibility of CP, NDF or ADF. The reason for the differences in the results between different trials could be that the REE levels used in the trials of Schwabe et al.…”

“…The mechanism could be that REE stimulated the digestive micro-organisms or enzymes (Liu et al, 2008) and increased ruminal fibrolytic and proteolytic activities (Yang et al, 2009). Schwabe et al (2011), however, reported that supplementing up to 300 mg REE citrate/kg DM to the rations of growing and fattening cattle, consisting of 25.3% REE or 38.7% REE, respectively (REE composition: 57.9% Ce, 34.0% La, 6.5% Pr and 1.6% other REE), did not affect the digestibility of CP, NDF or ADF. The reason for the differences in the results between different trials could be that the REE levels used in the trials of Schwabe et al (2011) were lower than in other trials.…”