ALBERT

Description: The recessional history of Niagara Falls in the present Niagara Gorge during the postglacial period has been a focus of study throughout this century. Radiocarbon ages of clam shells suggest that Niagara Falls migrated very slowly around the narrowed gorge section at Niagara Glen from 10,500 to 5500 yr B.P., when upper Great Lakes water bypassed Lake Erie and flowed to the Ottawa River via the outlet at North Bay, Ontario. Prior to that interval, river discharge and recession rates were similar to those at present, and similar rates resumed after 5200 yr B.P. By about 4500 yr B.P., the present gorge had intersected a buried gorge of the pre-late Wisconsinan Niagara River (St. Davids Gorge). The sediment derived from the excavated buried valley fill may be present as a distinct marker horizon in the sediments in southwestern Lake Ontario.

Description: SummaryThree separate nitrogen balance experiments were made in three consecutive years. Comparisons of nitrogen retention were made between late-pregnant (15–20 weeks) Greyface (Border Leicester ♂χ Scottish Blackface ♀) ewes given a basal diet of hay and molassed sugar-beet pulp cubes (SBP, 1·25 em diameter x ca. 3cm length) and when given additional nitrogen supplied as urea contained in molassed sugar-beet pulp cubes (SBPU). Both sugar-beet pulp materials were adequately supplemented with minerals and vitamins. Supplementation with urea significantly increased nitrogen retention.

Description: SUMMARYTwo groups of nine in-calf beef cows were given daily for the last 16 weeks of pregnancy and the first 6 weeks of lactation 1·35 increasing to 3·15 kg molassed sugarbeet pulp dry matter containing added urea together with oat straw ad libitum. Additionally, one group of cows received supplementary dicalcium phosphate which increased their total phosphorus intake from about 12 to 28 g P/day.In the absence of phosphorus supplementation, there was a marked and significant reduction in the concentration of phosphorus in the blood, and by the 4th week of lactation this was reflected in a decrease in radiographic density of the tail bones but not in a depletion of rib bone ash.During pregnancy a severely reduced phosphorus intake did not reduce either calf birth weight or the digestibility and voluntary intake of straw. An inadequate phosphorus intake during lactation resulted in a significant decline in voluntary straw consumption and digestibility. There was an accompanying decrease in metabolizable energy intake from about 78 to 55 MJ/day, an increased weight loss in the cows and a depression in their milk yield such as to significantly reduce calf live-weight gain.The long period of phosphorus inadequacy did not affect the subsequent satisfactory reproductive performance of the cows when both groups were transferred to grass and mated with a bull.

Description: SUMMARYPregnant beef heifers allowed ad libitum access to oat straw were given 2·7 kg molassed sugar-beet pulp alone or with additional dicalcium phosphate or urea or a combination of both materials in a Latin square design involving four feeding periods each of 21 days. Supplementation with urea to increase the total daily intake of digestible crude protein from about 130 to 290 g/day increased straw consumption by 20%. This increased the total intake of metabolizable energy from about 13 to 15 Meal/day. Increasing the total intake of phosphorus from about 6 to about 17 g P/day did not increase straw intake or digestibility or the total intake of metabolizable energy in either the presence or absence of additional urea.Supplementation with urea increased the concentration of urea and glucose in the blood plasma and the concentration of ammonia in the rumen liquor, but did not increase the concentrations or alter the proportions of rumen volatile fatty acids. Addition of urea tended to increase the digestibility of the dry matter and crude fibre of the straw. Phosphorus supplementation increased the concentration of phosphorus in the blood plasma.

Description: SUMMARYTwo similar experiments were conducted in consecutive years using a total of 26 pregnant beef cows. The two groups of 13 cows were given 2 kg molassed sugar-beet pulp (SBP)/day for the last 16 weeks of pregnancy and 3 kg SBP/day for the first 6 weeks of lactation with oat straw ad libitum. One group was given 250 g of a fully soluble liquid supplement (LS) containing urea, phosphoric acid, calcium and sodium chloride, trace elements and vitamins poured on to the SBP. The other group received no supplementary phosphorus but was given the same amounts of supplementary nitrogen (as crystalline urea) and calcium (as calcium carbonate) together with the same amounts of sodium chloride, trace elements and vitamins as were present in the LS. The LS provided 3.7 g P/day. The overall mean phosphorus intakes of the two groups were about 5.5 g (unsupplemented) and 10.5 g P (LS)/day.During pregnancy, reduced phosphorus intakes did not affect either the voluntary intake or digestibility of the straw. There was, however, a reduction in the blood phosphorus concentration for the cows which did not receive LS.After calving, the voluntary straw intake, digestibility of straw organic matter, metabolizablo energy intakes and blood phosphorus concentrations of the cows which received no phosphorus supplement were severely reduced. Using the present data and that from an earlier, similar experiment, a highly significant relationship was established between blood phosphorus concentration and voluntary straw intake during the period 5.6 weeks after calving for those cows with a blood phosphorus concentration below 1.0 mmol P/l. This relationship was voluntary straw intake (kg D.M./day) = 1.55 + 5.01 × blood phosphorus concentration (mmol/1).These results, obtained with individually fed, housed cattle, tend to suggest that a total phosphorus intake of only about 10.12 g P/day (of which 3.7 g was in the form of phosphoric acid) was adequate to maintain normal blood phosphorus concentration and voluntary straw intake and digestibility by these beef cows over the last 16 weeks of pregnancy and the first 6 weeks of lactation. This should be contrasted with the results of a similar experiment conducted earlier which clearly indicated that a daily intake of about 12 g P/day derived solely from sugar-beet pulp and oat straw was markedly inadequate.

Description: SUMMARYThree experiments were conducted to assess the effects of several methods of dietary presentation of 250 g/day of a fully soluble liquid supplement (LS) on the voluntary intake of oat straw by non-productive cows fitted with a rumen fistula (Expt 1), pregnant beef cows (Expt 2) and lactating beef cows (Expt 3). In each case the cows received fixed daily amounts of barley (2 kg for Expts 1 and 2; 3 kg for Expt 3). LS contained (g/kg) about 1100 crude protein (as urea), 30 calcium, 15 phosphorus and 50 salt plus trace elements and vitamins. In Expt 1, provision of LS in either the drinking water, or via the rumen fistula or sprayed on to the straw increased voluntary straw intake by about 12%. In Expt 2, provision of LS, whether by spraying on the straw or in a molasses lick, increased straw consumption, but giving LS in the drinking water did not. In both Expts 1 and 2 the digestibility of the oat straw was not significantly affected by the dietary supplement, any increases in metabolizable energy intake being reflexions of increased intakes. In Expt 3 there was no difference in the voluntary intake of oat straw by group-fed lactating beef cows offered LS in either the drinking water or as a molasses lick.Giving LS sprayed on the straw, or incorporating it into a molasses lick to housed animals, are convenient and practical methods of supplementing ruminant diets to increase their voluntary straw consumption. Inclusion of LS in drinking water gave inconsistent results, but the method warrants further investigation.

Description: Granular calcined magnesites originating from Spain, China and Greece and magnesium hydroxide powder were evaluated in a series of balance experiments conducted with wether sheep (c. 42 kg liveweight) given a basal ration of dried grass at Glasgow University Veterinary School between 1989 and 1994. Four Spanish ‘Agma’ products and three Spanish ‘Navarras’ products contained less material (0–104 g/kg)〉1000 μm diameter than four Chinese and four Greek materials 178–483 g/kg). The Spanish products had lower (18–45 g/kg) losses on ignition compared with the Chinese and Greek materials (53–112 g/kg). A fifth Greek product contained only 4 g/kg〉1000 μm diameter. In three experiments comparing supplementation of the basal diet with 2·0 g Mg as either magnesium hydroxide or as one of the three separate purchases of the commercial calcined magnesite sources, the powdered magnesium hydroxide had the highest mean apparent availability coefficient (0·30) (faecal increase method). The corresponding values were 0·24 (Agma and Navarras), 0·20 (Chinese) and 0·15 (Greek) (pooled s.e. 0·014, d.f. 10). Powdered magnesium hydroxide also had the highest (0·18) mean availability coefficient (urinary increase method) compared with 0·12 (Agma), 0·13 (Navarras), 0·14 (Chinese), 0·10 (Greek) (pooled s.e. 0·005, d.f. 10). In two subsequent experiments, Agma had a superior apparent availability coefficient (0·26) (faecal method) than either the Chinese (0·14) or the Greek materials (0·19). A finer grade of Greek calcined magnesite (0·25) was equivalent to Agma. For the 12 calcined magnesites evaluated in the three main experiments, significant (P

Description: This paper examines the relationship between resource development and aboriginal community and cultural impacts in Canada's north from the 1970s to the present. Based on a review of published literature, it is contended that northern centred scholarship can be conceptualised in two phases. These are firstly the community impacts phase (1970 to mid-1990s), a phase guided largely by a cultural politics of assimilation, a sociology of disturbance, and an anthropology of acculturation; and secondly the community continuity phase (mid-1990s to present), a phase underpinned by political empowerment, participatory social impact assessment, and the influence of cultural ecology. Due to these shifting political dynamics and research frameworks, and a lack of longitudinal research in the north over the last four decades, it is concluded that the nature of the relationship between resource development and aboriginal culture remains elusive and subject to wide ranging interpretation. Analysis shows that cultural impacts from resource development are dependent on the scale of development and spatial disturbance. It also shows growing political power in the north, a greater focus on community-based research, and renewed discussion of cultural continuity and how it is defined and assessed over time.