No abstract

An increasing worldwide interest in alternative fuel sources and in a more diversified energy matrix has provided incentives for the biodiesel industry, generating large amounts of the by-product crude glycerin, a potential alternative feed for dairy cows. A replicated 3×3 Latin square study was conducted to evaluate the effects of high concentrations of crude glycerin on dry matter intake, milk yield and composition, milk fatty acid profile, and blood metabolites of medium-yield cows. Ruminally cannulated Holstein cows (n=6; 587 ± 39 kg of body weight; 114 ± 29 d in milk; and 20 ± 1.5 kg/d milk yield) were used in the study. The experimental period included 2 wk for adaptation and 1 wk for data collection. Cows were fed diets containing 0 (control), 15, or 30% crude glycerin (83% glycerol). Cows were milked, milk weights were recorded twice daily, and milk samples were collected for milk quality analyses at d 18 and 19 in each experimental period. Feeding cows with crude glycerin linearly decreased dry-matter intake, the 3.5% fat-corrected milk, and the solid-corrected milk yield. Hepatic enzymes were not affected by dietary treatments, except gamma-glutamyl transferase, which was decreased with the 15% crude glycerin diet. Serum glucose and albumin showed quadratic effect with increasing inclusion of crude glycerin. Plasma cholesterol as well as total protein linearly decreased with increasing inclusion of crude glycerin. Milk fat concentration and yield showed a quadratic effect of treatments. Solid yield decreased linearly with increasing inclusion of crude glycerin. Odd-chain fatty acids and conjugated linoleic acid in milk fat linearly increased with addition of crude glycerin in the diets. Together, these results suggest that crude glycerin has potential to replace corn; however, feeding diets in which corn is replaced with crude glycerin at 30% of dietary DM greatly reduces animal performance.

-Two studies were conducted to evaluate the effects of crude glycerin on feed intake, performance, carcass characteristics, and total digestibility of Nellore bulls. In experiment 1, cattle (n = 30) were fed a control diet without crude glycerin and diets containing 7.5, 15, 22.5, and 30% crude glycerin, for 103 d. Animals were harvested and data of carcass characteristics were collected. In experiment 2, a digestibility trial was performed using indigestible acid detergent fiber (iADF) as internal marker, and five rumen-cannulated steers. Both experiments were conducted as a randomized complete block design and data were analyzed using mixed procedures. In experiment 1 no differences were observed among treatments on dry matter intake, and performance variables. Regarding carcass characteristics, no effect was observed, except for carcass fat estimates, which were greater in treatments with crude glycerin. In experiment 2, crude glycerin promoted a decrease in digestibility of fibrous fractions NDF and HEM, and increased digestibility of crude protein by 6%. Although it caused negative effect on digestibility of fibrous fraction of diets, crude glycerin can be a good energy source for Nellore bulls, since no losses are observed on performance and carcass characteristics when animals are fed up to 30% of this by-product.

As the biodiesel industry produces a large surplus of crude glycerin, this by-product is increasingly being considered as an attractive source of energy to replace corn in livestock diets. The objective of this study was to evaluate how the inclusion of up to 30% crude glycerin in Nellore cattle diets affects ruminal parameters such as pH, ammonia, and volatile fatty acids as well as greenhouse gas production, and concentration of the protozoal and bacterial fractions. Five ruminally cannulated Nellore steers were randomly assigned in a 5 Â 5 Latin square design and fed diets containing 30% corn silage and 70% concentrate composed of sunflower meal, corn grain, soybean hulls, minerals, and 0, 7.5, 15, 22.5, or 30% crude glycerin (860 g glycerol/kg). After 14 d of adaptation, animals were submitted to rumen content sampling for 7 d. With the supplementation of glycerin in the diets, total VFA and acetate concentrations decreased (linear, P¼ 0.03, Po 0.0001, respectively), and propionate concentrations increased (linear, P¼ 0.007; quadratic, P ¼0.008), leading to an acetate to propionate ratio decrease (linear, P o 0.0001). The rumen ammonia was not affected while pH was quadratically affected and was lesser for glycerin treatments (quadratic, P¼ 0.04). Methane production was reduced (linear, Po 0.0001) when glycerin was added, as well as the CO 2 (linear, P o0.0001; quadratic, P ¼0.0001; cubic, P o0.0001). The concentration of liquid phase microorganisms was not affected, while the concentration of particle-associated bacteria fraction was decreased by the addition of crude glycerin in the diets. The inclusion of up to 30% of crude glycerin in diets for beef cattle decreased ruminal concentration of total VFA and acetate, increased propionate, reduced concentration of particle-associated bacteria, and decreased production of methane.

The effects of high concentrations of crude glycerin were investigated in diets for feedlot lambs. Forty crossbred (Santa Ines × Dorper) uncastrated male lambs (21.7 ± 2.7 kg bodyweight) were assigned to a complete randomised block and subjected to four experimental diets containing 0, 100, 200, or 300 g crude glycerin/kg DM. Animals were weighed at 14-day intervals and were harvested when they reached ~35 kg bodyweight. The feed intake, feeding behaviour, growth performance, carcass and meat traits, and edible non-carcass components were evaluated. The inclusion of more than 100 g/kg crude glycerin in the diets increased days on feed and decreased DM intake and average daily gain. Crude glycerin increased number of chews and the time spent chewing per feed bolus. There were no effects of crude glycerin on pH and colour of Longissimus muscle at 45 min or 24 h after slaughter, as well as on other carcass and edible non-carcass characteristics. The addition of crude glycerin reduced perirenal fat without detrimental effect on others fat deposition sites. In conclusion, the addition of up to 100 g/kg DM in diets for crossbred finishing lambs seems to be the most interesting strategy, as it promotes greatest animal performance. However, the inclusion of up to 300 g/kg DM of the by-product could be possible depending on glycerin market price and the structure of feedlot operation, with favourable economic results despite high inclusions reflect in greater number of days on feed.

Crude glycerin, a by-product of the biodiesel industry, has been used as a strategic ingredient in intensive ruminant production systems, mainly in substitution of starch-rich ingredients. The present study was performed to evaluate the effects of the inclusion of up to 30% of crude glycerin in diets for feedlot sheep, on ruminal parameters, such as pH, NH 3-N and volatile fatty acids concentrations, in situ degradability, as well as in vitro greenhouse gas production and in vitro digestibility. Eight ruminally-cannulated male Santa Inês × Dorper sheep (64.5 ± 8.5 kg) were distributed in a replicated 4 × 4 Latin square design. The experimental diets contained 0, 10, 20 or 30% of crude glycerin and were labeled as G0, G10, G20 and G30, respectively. The crude glycerin totally replaced the corn cracked grain in treatment G30. The inclusion of crude glycerin in the diets tended to promote a quadratic effect in DMI, with greater values observed for treatments G10 and G20. Crude glycerin tended to increase the ruminal pH and NH 3-N, but linearly reduced the total molar concentration of VFA, acetic, butyric, isobutyric and isovaleric acids. Treatments linearly increased in vitro DM digestibility of diets and linearly reduced NDF digestibility. The inclusion of crude glycerin in the diets linearly decreased the in vitro total gas and CO 2 production (mL/g degraded) and tented to reduce CH 4 (mL/g degraded). A linear increase of soluble fraction in water ("a") of the diets was observed with the increasing inclusion of crude glycerin. The insoluble but potentially degradable fraction ("b") of DM and NDF of the diets were linearly decreased and increased, respectively. The potential ruminal degradation of the diets was markedly and linearly increased with the increasing inclusion of the by-product. The replacement of corn cracked grain by crude glycerin (up to 30% DM) changes rumen fermentation parameters, decreasing VFA production, in vitro total gas production and CH 4. Additionally, the potential and effective degradation as well as in vitro DM digestibility of diets are improved while fiber digestibility is impaired.

No abstract

This study aimed to evaluate the effects of glycerin supplements in the diet of beef cattle by assessing intake, apparent nutrient digestibility, ruminal pH, ruminal ammonia concentrations, and blood parameters. The study was conducted at the São Paulo State University (UNESP, Jaboticabal campus) using five crossbred cattle in an experiment employing a 5 x 5 Latin square design. Cattle diet treatments included zero, 50, 100, 150, and 200 g kg -1 dry matter of glycerin. Feed, leftover feed, and faeces were collected to determine intake and digestibility. Samples of ruminal liquid were collected at -1, 0, 1, 2, 4, 6 and 8 h after feeding to determine pH and ruminal ammonia. Blood was collected four hours after the morning feeding from the coccygeal vein. Replacing maize with glycerin resulted in lower concentrations of ether extract and non-fibre carbohydrates in the diets, leading to a linear decrease in the intake of these nutrients (P<0.05). The digestibility of neutral detergent fibre and nonfibre carbohydrates also decreased linearly with increasing dietary glycerin concentrations (P<0.05). The results for ruminal fermentation parameters showed a linear decrease (P<0.05) in the ruminal concentration of N-NH 3 with increasing dietary levels of glycerin; however, ruminal pH was not affected (P>0.05). Serum concentrations of urea, triglycerides, cholesterol, and plasma glucose concentrations were within normal ranges based on the literature. The inclusion of glycerin in the cattle diet altered rumen fermentation, reducing the concentration of N-NH 3 , the digestibility of neutral detergent fiber and non-fiber carbohydrates. g kg -1 de glicerina na MS. Para determinação do consumo e digestibilidade foram realizadas colheitas de alimentos, sobras e fezes. Para determinação do pH e amônia ruminal foram colhidas amostras de líquido ruminal nos tempos -1, 0, 1, 2, 4, 6 e 8 horas após a alimentação. As colheitas de sangue foram realizadas 4h após a alimentação matutina via veia coccígea. A substituição do milho pela glicerina resultou em menores concentrações de extrato etéreo e carboidratos não fibrosos nas dietas, o que levou a redução linear no consumo desses nutrientes (P<0,05). As digestibilidades da fibra em detergente neutro e de carboidratos não fibrosos apresentaram redução linear com o aumento da concentração de glicerina na dieta (P<0,05). Em relação à fermentação ruminal, houve decréscimo linear (P<0,05) na concentração ruminal de N-NH 3 com o aumento da inclusão desse subproduto, mas o pH ruminal não foi influenciado (P>0,05). As concentrações séricas de ureia, triglicerídeos e colesterol ficaram dentro dos níveis considerados normais pela literatura assim como as concentrações plasmáticas de glicose. A inclusão de glicerina na dieta de bovinos alterou a fermentação ruminal, reduzindo a concentração de N-NH 3 , a digestibilidade da fibra em detergente neutro e dos carboidratos não fibrosos. Palavras-chave: Biodiesel, fermentação ruminal, metabolismo, subproduto