title: The effects of tannins-containing ground pine bark diet upon nutrient digestion, nitrogen balance, and mineral retention in meat goats.
abstract: BACKGROUND
  Pine bark is a rich source of phytochemical compounds including tannins, phenolic acids, anthocyanins, and fatty acids. These phytochemicals have potential to significantly impact on animal health and animal production. The goal of this work is to measure the effects of tannins in ground pine bark as a partial feed replacement on feed intake, dietary apparent digestibility, nitrogen balance, and mineral retention in meat goats.
  
  
  RESULTS
  Eighteen Kiko cross goats (initial BW = 31.8 ± 1.49 kg) were randomly assigned to three treatment groups (n = 6). Dietary treatments were tested: control (0 % pine bark powder (PB) and 30 % wheat straw (WS)); 15 % PB and 15 % WS, and 30 % PB and 0 % WS. Although dry matter (DM) intake and digestibility were not affected (P > 0.10) by feeding PB, neutral detergent fiber (linear; P = 0.01), acid detergent fiber (linear; P = 0.001) and lignin digestibility (linear; P = 0.01) decreased, and crude protein (CP) digestibility tended to decrease (P = 0.09) as PB increased in the diet, apparent retention of Ca (P = 0.09), P (P = 0.03), Mg (P = 0.01), Mn (P = 0.01), Zn (P = 0.01) and Fe (P = 0.09) also increased linearly. Nitrogen intake and fecal N excretion were not affected (P > 0.05) by addition of PB in the diet, but N balance in the body was quadratically increased (P < 0.01) in the 15 % PB diet compared to other diets. This may be due to more rumen escape protein and less excreted N in the urine with the 15 % PB diet. The study showed that a moderate level of tannin-containing pine bark supplementation could improve gastrointestinal nitrogen balance with the aim of improving animal performance.
  
  
  CONCLUSIONS
  These results suggest that tannin-containing PB has negative impact on fiber, lignin, and protein digestibility, but positively impacted on N-balance.
authors.affiliation: Department of Agricultural and Environmental Sciences, Tuskegee University, Tuskegee, AL USA.
authors.forename: Byeng Ryel
authors.initials: BR
authors.lastname: Min
authors.affiliation: Department of Agricultural and Environmental Sciences, Tuskegee University, Tuskegee, AL USA.
authors.forename: Sandra
authors.initials: S
authors.lastname: Solaiman
authors.affiliation: Agricultural Research Station, Fort-Valley State University, Fort-Valley, GA USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Terrill
authors.affiliation: School of Agriculture, Policy and Development, University of Reading, P.O. Box 236, Berkshire Reading, RG6 6AT UK.
authors.forename: Aina
authors.initials: A
authors.lastname: Ramsay
authors.affiliation: School of Agriculture, Policy and Development, University of Reading, P.O. Box 236, Berkshire Reading, RG6 6AT UK.
authors.forename: Irene
authors.initials: I
authors.lastname: Mueller-Harvey
keywords: Digestibility; Goats; Phytochemicals; Tannins