ABSTRACT
The use of additional supplement can affect ruminant performance by increasing the animal weight gain and maximizing profits from the activity. Thus, the objective of this study was to evaluate the influence of protein-energy supplementation on microbial synthesis, animal performance, nutrient digestibility, and body composition of Brangus x Zebu steers on pasture. The experiment lasted 160 days and included 36 animals divided into two groups; 18 steers received protein-energy supplementation (PES), and the other 18 received non-supplementation (NPES). Individual pasture intake and nutrient digestibility were estimated using the double indicator technique-chromium oxide and lignin in potassium permanganate. Spot urine samples were collected from 36 animals to determine creatinine, allantoin, and uric acid concentrations. All animals were slaughtered at the end of the experiment to evaluate body composition. There was increase in intake (P < 0.001) and dry matter digestibility (P = 0.01); it resulted in higher animal weight gain (P < 0.001) receiving supplementation. However, there was no difference (P > 0.05) in pasture nutrient intake between treatments. Supplementation increased microbial nitrogen (P < 0.001). For body composition, the model identity test that was applied showed no difference (P > 0.05) between the models, so it was adopted a common equation for both treatments. There was no difference (P > 0.05) for body composition between treatments. Therefore, the use of protein-energy supplementation for steers on pasture allowed higher microbial protein synthesis and better utilization of nutrients, which resulted in better animal performance. The use of protein-energy supplementation at 0.6% BW did not alter the carcass composition of Brangus x Zebu steers. However, it recommends protein-energy supplementation in pasture systems during the rainy period or using an irrigation system.
Subject(s)
Animal Feed/analysis , Body Composition , Cattle , Diet/veterinary , Dietary Supplements , Weight Gain , Animal Husbandry , Animal Nutritional Physiological Phenomena , Animals , Digestion , Energy Intake , Male , Nitrogen/metabolism , Protein Biosynthesis , Tropical ClimateABSTRACT
BACKGROUND: The impact of prion proteins in the rules that dictate biological reproduction is still poorly understood. Likewise, the role of prnt gene, encoding the prion-like protein testis specific (Prt), in ram reproductive physiology remains largely unknown. In this study, we assessed the effect of Prt in ovine fertilization by using an anti-Prt antibody (APPA) in fertilization medium incubated with spermatozoa and oocytes. Moreover, a computational model was constructed to infer how the results obtained could be related to a hypothetical role for Prt in sperm-zona pellucida (ZP) binding. METHODS: Mature ovine oocytes were transferred to fertilization medium alone (control) or supplemented with APPA, or pre-immune serum (CSerum). Oocytes were inseminated with ovine spermatozoa and after 18 h, presumptive zygotes (n=142) were fixed to evaluate fertilization rates or transferred (n=374) for embryo culture until D6-7. Predicted ovine Prt tertiary structure was compared with data obtained by circular dichroism spectroscopy (CD) and a protein-protein computational docking model was estimated for a hypothetical Prt/ZP interaction. RESULTS: The fertilizing rate was lower (P=0.006) in APPA group (46.0+/-6.79%) when compared to control (78.5+/-7.47%) and CSerum (64.5+/-6.65%) groups. In addition, the cleavage rate was higher (P<0.0001) in control (44.1+/-4.15%) than in APPA group (19.7+/-4.22%). Prt CD spectroscopy showed a 22% alpha-helical structure in 30% (m/v) aqueous trifluoroethanol (TFE) and 17% alpha in 0.6% (m/v) TFE. The predominant alpha-helical secondary structure detected correlates with the predicted three dimensional structure for ovine Prt, which was subsequently used to test Prt/ZP docking. Computational analyses predicted a favorable Prt-binding activity towards ZP domains. CONCLUSIONS: Our data indicates that the presence of APPA reduces the number of fertilized oocytes and of cleaved embryos. Moreover, the CD analysis data reinforces the predicted ovine Prt trend towards an alpha-helical structure. Predicted protein-protein docking suggests a possible interaction between Prt and ZP, thus supporting an important role for Prt in ovine fertilization.
Subject(s)
Antibodies, Monoclonal/pharmacology , Fertilization in Vitro/drug effects , Prions/metabolism , Zona Pellucida/metabolism , Amino Acid Sequence , Animals , Antibodies, Monoclonal/immunology , Circular Dichroism , Egg Proteins/chemistry , Egg Proteins/genetics , Egg Proteins/metabolism , Embryo, Mammalian/drug effects , Embryo, Mammalian/embryology , Embryo, Mammalian/metabolism , Female , Male , Membrane Glycoproteins/chemistry , Membrane Glycoproteins/genetics , Membrane Glycoproteins/metabolism , Models, Molecular , Molecular Sequence Data , Prions/chemistry , Prions/immunology , Protein Binding , Protein Conformation/drug effects , Protein Structure, Secondary/drug effects , Protein Structure, Tertiary , Receptors, Cell Surface/chemistry , Receptors, Cell Surface/genetics , Receptors, Cell Surface/metabolism , Sequence Homology, Amino Acid , Sheep , Sperm-Ovum Interactions/drug effects , Time Factors , Trifluoroethanol/chemistry , Trifluoroethanol/pharmacology , Zona Pellucida GlycoproteinsABSTRACT
A hallmark of prion diseases or transmissible spongiform encephalopaties is the conversion of the cellular prion protein (PrP(C)), expressed by the prion gene (prnp), into an abnormally folded isoform (PrP(Sc)) with amyloid-like features that causes scrapie in sheep among other diseases. prnp together with prnd (which encodes a prion-like protein designated as Doppel), and prnt (that encodes the prion protein testis specific--Prt) with sprn (shadow of prion protein gene, that encodes Shadoo or Sho) genes, constitute the "prion gene complex". Whereas a role for prnd in the proper functioning of male reproductive system has been confirmed, the function of prnt, a recently discovered prion family gene, comprises a conundrum leading to the assumption that ruminant prnt is a pseudogene with no protein expression. The main objective of the present study was to identify Prt localization in the ram reproductive system and simultaneously to elucidate if ovine prnt gene is transcribed into protein-coding RNA. Moreover, as Prt is a prnp-related protein, the amyloid propensity was also tested for ovine and caprine Prt. Recombinant Prt was used to immunize BALB/c mice, and the anti-Prt polyclonal antibody (APPA) immune response was evaluated by ELISA and Western Blot. When tested by indirect immunofluorescence, APPA showed high avidity to the ram sperm head apical ridge subdomain, before and after induced capacitation, but did not show the same behavior against goat spermatozoa, suggesting high antibody specificity against ovine-Prt. Prt was also found in the testis when assayed by immunohistochemistry during ram spermatogenesis, where spermatogonia, spermatocytes, spermatids and spermatozoa, stained positive. These observations strongly suggest ovine prnt to be a translated protein-coding gene, pointing to a role for Prt protein in the ram reproductive physiology. Besides, caprine Prt appears to exhibit a higher amyloid propensity than ovine Prt, mostly associated with its phenylalanine residue.
