Relationships of feedlot feed efficiency, performance, and feeding behavior with metabolic rate, methane production, and energy partitioning in beef cattle

Residual feed intake (RFI) is the difference between the actual and expected feed intake of an animal based on its BW and growth rate over a specified period. The biological mechanisms underlying the variation in feed efficiency in animals with similar BW and growth rate are not well understood. This study determined the relationship of feedlot feed efficiency, performance, and feeding behavior with digestion and energy partitioning of 27 steers. The steers were selected from a total of 306 animals based on their RFI following feedlot tests at the University of Alberta Kinsella Research Station. Selected steers were ranked into high RFI (RFI > 0.5 SD above the mean, n = 11), medium RFI (RFI +/- 0.5 SD above and below the mean, n = 8), and low RFI (RFI < -0.5 SD below the mean, n = 8). The respective BW +/- SD for the RFI groups were 495.6 +/- 12.7, 529.1 +/- 18.6, and 501.2 +/- 15.5 kg. Digestibility and calorimetry trials were performed on a corn-or barley-based concentrate diet in yr 1 and 2, respectively, at 2.5 x maintenance requirements. Mean DMI (g/kg of BW(0.75)) during the measurements for high-, medium-, and low-RFI groups, respectively, were 82.7 +/- 2.0, 78.8 +/- 2.6, and 81.8 +/- 2.5 and did not differ (P > 0.10). Residual feed intake was correlated with daily methane production and energy lost as methane (r = 0.44; P < 0.05). Methane production was 28 and 24% less in low-RFI animals compared with high- and medium-RFI animals, respectively. Residual feed intake tended to be associated (P < 0.10) with apparent digestibilities of DM (r = -0.33) and CP (r = -0.34). The RFI of steers was correlated with DE (r = -0.41; P < 0.05), ME (r = -0.44; P < 0.05), heat production (HP; r = 0.68; P < 0.001), and retained energy (RE; r = -0.67; P < 0.001; energy values are expressed in kcal/kg of BW(0.75)). Feedlot partial efficiency of growth was correlated (P < 0.01) with methane production (r = -0.55), DE (r = 0.46), ME (r = 0.49), HP (r = -0.50), and RE (r = 0.62). With the exception of HP (r = 0.37; P < 0.05), feed conversion ratio was unrelated to the traits considered in the study. Feeding duration was correlated (P < 0.01) with apparent digestibility of DM (r = -0.55), CP (r = -0.47), methane production (r = 0.51), DE (r = -0.52), ME (r = -0.55), and RE (r = -0.60). These results have practical implications for the selection of animals that eat less at a similar BW and growth rate and for the environmental sustainability of beef production.     

Characterization and distribution of mating type genes in the dothistroma needle blight pathogens

ABSTRACT Dothistroma septosporum and D. pini are the two causal agents of Dothistroma needle blight of Pinus spp. in natural forests and plantations. Degenerate primers amplified portions of mating type genes (MAT1-1-1 and MAT1-2) and chromosome walking was applied to obtain the full-length genes in both species. The mating-type-specific primers designed in this study could distinguish between the morphologically similar D. pini and D. septosporum and between the different mating types of these species. Screening of isolates from global collections of D. septosporum showed that only MAT2 isolates are present in Australian and New Zealand collections, where only the asexual form of the fungus has been found. In contrast, both mating types of D. septosporum were present in collections from Canada and Europe, where the sexual state is known. Intriguingly, collections from South Africa and the United Kingdom, where the sexual state of the fungus is unknown, included both mating types. In D. pini, for which no teleomorph is known, both mating types were present in collections from the United States. These results provided new insights into the biology and global distribution of two of the world's most important pine pathogens and should facilitate management of the diseases caused by these fungi.     

Environmental Impacts of Acid Leachate Derived from Coal-Storage Piles upon Groundwater

Leachate emanating from a coal-storage area at an electricutility plant in Northwest Indiana (U.S.A.) is impacting groundwater quality. This assessment is based on results of along-term groundwater monitoring program conducted at Purdue University's Wade Utility Plant where a monthly average of 32,000metric tons of both high- and low-sulfur coal are stored. Groundwater from both a perched and major aquifer (the WabashValley Aquifer) as well as surface water from a large retentionpond were sampled monthly for 34 consecutive months. Such a long-term, continuous sampling scheme proved beneficial in identifying seasonal trends and anomalies within the chemistryof ground- and surface waters. Data show elevated concentrationsof sulfate and hardness in the perched zones and the WabashValley Aquifer (WVA). Lead in the WVA has also been reported ata concentration greater than the state maximum contaminant level, while several metals (Be, Cd, Cu, Pb, Ni, Se, and Zn) containedwithin retention-pond sediments have the highest concentrationsin aquatic sediments ever reported within the State of Indiana.Due to the buffering capacity of carbonate minerals in underlyingunconsolidated deposits, the acidic pH of coal-pile leachate is raised to values typical for groundwater in carbonate terrain common in Northwest Indiana. Further ameliorating the input of acid percolation is the dilution capabilities of both the WVA and the recharge pond. Hence, sites without such advantages would exhibit a greater degree of groundwater contamination than what is observed at Purdue's coal-storage facility.     

Basal anthropoids from Egypt and the antiquity of Africa's higher primate radiation

Early anthropoid evolution in Afro-Arabia is poorly documented, with only a few isolated teeth known from before approximately 35 million years ago. Here we describe craniodental remains of the primitive anthropoid Biretia from approximately 37-million-year-old rocks in Egypt. Biretia is unique among early anthropoids in exhibiting evidence for nocturnality, but derived dental features shared with younger parapithecids draw this genus, and possibly >45-million-year-old Algeripithecus, into a morphologically and behaviorally diverse parapithecoid clade of great antiquity.     

Phosphorylation by cyclin B-Cdk underlies release of mitotic exit activator Cdc14 from the nucleolus

Budding yeast protein phosphatase Cdc14 is sequestered in the nucleolus in an inactive state during interphase by the anchor protein Net1. Upon entry into anaphase, the Cdc14 early anaphase release (FEAR) network initiates dispersal of active Cdc14 throughout the cell. We report that the FEARnetwork promotes phosphorylation of Net1 by cyclin-dependent kinase (Cdk) complexed with cyclin B1 or cyclin B2. These phosphorylations appear to be required for FEAR and sustain the proper timing of late mitotic events. Thus, a regulatory circuit exists to ensure that the arbiter of the mitotic state, Cdk, sets in motion events that culminate in exit from mitosis.     

Effects of changes in frequency of reticular contractions on fluid and particulate passage rates in cattle

Four ruminally cannulated Hereford steers (531 +/- 32 kg) without weights (control; C) or with 24-kg weights (W) in the rumen were used in a double crossover design experiment to determine the effects of changes in frequency of reticular contractions at maintenance feed intakes on passage rates of particulate matter and fluid from the rumen. Duration of reticular contractions, apparent digestibilities and heat and methane productions were also determined. Weights in the rumen had no effect (P = .07) on frequency of reticular contractions before feeding; however, frequencies of reticular contractions were higher in C than in W steers during feeding (P = .03) and after feeding (P = .05). Weights in the rumen increased the average duration of contractions before feeding (P = .04), during feeding (P = .01) and after feeding (P = .05) by 12, 15 and 15%, respectively. Fractional outflow rates of ruminal and whole gastrointestinal particulate matter were 38% and 49% lower (P = .001) in C than in W steers, respectively. Weights in the rumen reduced (P = .001) methane production (liters/d) by 29%. Methane production was inversely correlated with fractional outflow rate for ruminal particulate matter (r = -.53; P = .034). Heat productions for W and C steers were 12.3 and 12.6 Mcal/d, respectively. Weights in the rumen had no effect on apparent digestibility. Duration of reticular contractions, in contrast to frequency of contractions, was the important factor influencing passage rates of both ruminal fluid and particulate matter. Methane production was decreased when passage rates were increased.(ABSTRACT TRUNCATED AT 250 WORDS)