To identify separate effects of gender, castration and exogenous oestrogen on growth, castrated lambs of both sexes and entire male lambs (n = 8) were implanted subcutaneously with three sizes of oestradiol-17 beta implants, or not implanted, and grazed on ryegrass and white clover pasture for 180 days. A group of non-implanted entire female lambs (n = 8) was run together with the others. Non-implanted entire male lambs grew faster, had heavier heads, less internal, non-carcass fat and more protein and less fat and water in the carcass than non-implanted entire females. In addition, they had higher 12th vertebral spine, thicker tibia, and heavier and larger humerus than entire female lambs. Castration of male lambs reduced live-weight gain, weight of head and content of protein in the carcass whereas it increased carcass fat content. In addition, it caused lengthening of cannon bones and reduced height of 12th vertebral spine and length of tibia. In females, gonadectomy increased height of 12th vertebral spine and diameter to length ratio of the radius. Oestradiol treatment increased live-weight gain, reduced total internal and carcass fat, and increased water and protein content of the carcass in gonadectomized animals of either sex, and increased weight of carcass and head in spayed ewe lambs. Oestradiol treatment inhibited longitudinal growth of cannon bones and stimulated that of vertebral column and ribs, but had little effect on the dimensions of limb bones apart from increasing their diameter. Oestradiol treatment had no effect on muscle length but increased muscle girth and weight, except for m. splenius in ram lambs where muscle weight was reduced. Effects of oestradiol on skeletal measurements in most cases were linearly related to dose of oestradiol. It was concluded that the variable effects of sex steroids on the skeleton were related to the differential pattern of skeletal maturation. In early maturing bones acceleration of the growth process by an exogenous sex steroid caused elongation to cease prematurely, whereas in late-maturing bones the acceleration effect on elongation did not result in premature cessation. This observation may explain the often contradictory reports in the literature on the effects of sex steroids on linear growth of bone.
The present experiment was conducted to quantify the net fluxes of both free and peptide amino acids across the mesenteric and stomach portions of the portal-drained viscera (PDV) of three yak cows (172.3 +/- 18.6 kg, BW) fed a straw-concentrate diet at maintenance level. Yaks had been fitted with sampling catheters in the portal vein, mesenteric artery and mesenteric vein prior to its convergence with the gastrosplenic vein. Blood how was determined by measuring the dilution of para-aminohippurate (PAH) infused constantly into a distal mesenteric vein. Amino acids in the deproteinized plasma were analysed before and after acid hydrolysis. The increased amino acids after acid hydrolysis were considered as peptide-bound amino acids (PAA). The fluxes of free amino acids (FAA) and PAA across PDV and mesenteric-drained viscera (MDV) were calculated as the product of venoarterial differences and plasma flow. Flux across the stomach viscera (SDV) was calculated as the difference between portal and mesenteric fluxes. Portal blued flea; was 389 l/h or 2.32 l/h kg BW, of which 37% was contributed by the mesenteric vein. There was net appearance of a large quantity of PAA across PDV. which accounted for 92% of the total nonprotein amino acid flux. Net release of PAA and FAA in SDV accounted for 78% and 42% of the net release in PDV. respectively. These results suggest that in yaks. peptide possibly is the primary form of amino acid absorption, and that the stomach area probably is the major site of peptide absorption.
In order to understand better the factors which influence the persistence or non-persistence of Lolium perenne and Trifolium repens on damp hill land in a wet climate, swards in mid-Wales which had been converted from semi-natural rough grazing (predominantly Molinia caerulea or Nardus stricta or Agrostis/Festuca/Nardus) in 1961-81 were examined in 1982 and 1999, using a point quadrat technique. There was a marked decline between 1982 and 1999 in the proportion of L. perenne in the majority of the study areas. On the other hand, in 1999 the oldest swards (sown 30-38 years before) contained at least as high a proportion of L. perenne (22% of sward on average) as the younger swards (sown 18-29 years before). In two swards sown 25-26 years before, at 390-445 m above sea level, which received 95 kg N/ha per year, L. perenne was 36% of sward. On the other hand, no L. perenne was recorded on three swards which were no longer receiving fertilizer and which were being grazed at a greatly reduced stocking rate. The proportion of T. repens was rather low and declined between 1982 and 1999 (from 10 to 4% of sward on average). The application of more lime and more K and perhaps less N would probably have increased the proportion of T, repens. On at least one farm, the use of MCPA against Cirsium spp. had probably reduced the proportion of T. repens. There were positive correlations between the proportion of L. perenne and the proportions of T. repens and Poa spp. There were negative correlations between L. perenne and each of Agrostis spp., Festuca spp. and Holcus lanatus and also between T. repens and Agrostis spp. The proportion of Poa spp. was positively correlated with exchangeable Ca, nitrate-N and total N in soil and negatively correlated with exchangeable acidity.
Growth and efficiencies of nitrogen and energy utilization for growth by 72 young British Friesian steers (initial live weight (LW) 110 kg) offered a well preserved, formic acid-treated, perennial ryegrass silage with and without supplements of fish meal were examined. Silage was offered either alone or mixed with 50, 100 or 150 g fish meal/kg silage dry matter (DM) and each diet was offered either ad libitum or intakes were restricted to 16, 19 or 22 g dietary DM/kg LW/day. Treatments were imposed over a period of 132 days, Body component weight gains were determined by comparative slaughter. Increasing the level of either feeding or fish meal increased rates of empty body weight gain linearly (P 0.01). Consequently, in terms of whole body composition, animals given fish meal were leaner than animals offered silage alone. Fishmeal supplementation had no significant effect on the composition of the carcass but increased the concentration of protein in the liver and gastrointestinal tract. The increase in nitrogen intake associated with feeding fish meal resulted in a reduction in the efficiency of nitrogen utilization as level of fish meal increased. Nitrogen intake required for maintenance was estimated to be 1.054 g/kg LW0.75. In spite of marked differences in the composition of the empty body-weight gain, there was no evidence to support an effect of fish meal on the efficiency of metabolizable energy (ME) utilization for growth (k(f)) which was estimated to be 0.346 on the basis of data scaled by LW0.75. ME intake required for maintenance (MEm) was estimated to be 0.536 and 0.502 MJ/kg LW0.75] for silage alone and the 150 g fish-meal level respectively.
The effects of different plant arrangements (conventional single rows v. paired rows at a standard density of 55-67 thousand three-bud setts/ha) with different intercropped green manuring strategies with Sesbania aculeata (none v. ploughed in after 4 and 6 weeks) and with different amounts of nitrogen (N) fertilizers (0, 75 and 150 kg/ha) were studied in sugarcane crops planted after wheat or mustard and in its first ratoon. The yield of millable cane from the planted sugarcane was not affected by intercropped green manuring or plant arrangement but was increased by fertilizer N after both wheat and mustard. The residues from the green manuring and fertilizer N both increased the yield of the following crop of ratoon sugarcane by 9-10% with the residues increasing the numbers and length of millable canes and the fertilizer N the number, girth and weight of the millable canes. None of the treatments affected the quality of cane juice in either the planted cane or the ratoon crop. Residues from the green manures and the N fertilizer treatments increased the organic carbon content and available N in the soils.
The response of eight long-duration pigeonpea [Cajanus cajan (L) Millsp.] genotypes to irrigation was studied at Gwalior in Central India during the 1990-91, 1991-92 and 1992-93 growing seasons on an Inceptisol. The crop was grown at two spacings as it was expected that crop density could interact with the crop's ability to extract soil moisture. The irrigation treatment received furrow irrigation four times during the 1990-91 and 1992-93 seasons and twice during the 1991-92 season. Grain yields of all genotypes were 11% higher when planted at higher density than at low density. There was a differential variation in yield and harvest index among genotypes due to season but not due to spacing and irrigation suggesting the validity of the present approach of testing genotypes under optimum conditions. Grain yield declined by 21% from the 1990 to 1992 season. The decline was > 1 t/ha in some cultivars (ICPL 366, GW3), and between 0.5 and 1.0 t/ha in others (NP [WR] 15, ICP 87143 and ICPL 84072). In others (Bahar, ICP 9174, ICP 8860) the yield fluctuation was < 0.5 t/ha. The genotypes' mean yields were as high as 2.7 t/ha for ICPL 87143, ICPL 84072 and ICPL 366. There was a significant reduction in both grain yield (16%), and also above-ground plant dry mass (18 %) due to soil moisture limitation in the unirrigated treatment. Both the above-ground plant dry mass and grain yields were significantly more at high plant density than at lower plant density especially with irrigation. The genotypes were found to differ in their response to production environment (irrigation, spacing and to the undefined differences of the 3 years). Genotypic variation in yield within a production environment was found to vary in relation to changes in harvest index and across environment (irrigation, seasons) due to variation in total dry matter production. A lack of negative relationship between the total dry matter and harvest index suggests the possibility of optimizing both for obtaining higher yield from long-duration genotypes.
The tropical perennial clover, T. sempilosum, and the species, T. repens, exhibited both similarities and differences in their nodulation characteristics following Rhizobium inoculation. Both T. semipilosum and T. repens were infected via root hairs, formed indeterminate nodules and commenced active nitrogen-fixation approximately 1 week after inoculation. Effective Rhizobium strains produced on average four nitrogen-fixing nodules per T. semipilosum plant, predominantly in the upper region of the tap root. In contrast, 65% of the average 15 nodules per T. repens plant were induced on lateral roots. The Rhizobium strain-ANU843, effective (Nod(+)Fix(+)) on T. repens, caused root hair branching and twisting on T. sempilosum, although plants did not fix nitrogen, indicative of an ineffective host-strain interaction. Such ineffective interactions were associated with increased total numbers of nodule-like structures on T. semipilosum; these nodules were atypically associated with, or in close proximity to, lateral roots. Using a GUS gene-modified rhizobia to monitor nodule occupancy, a third of the total nodule-like structures formed from the incompatible interactions showed a positive GUS reaction, indicating that colonization by Rhizobium strains of some of the nodule-like structures had occurred. Moreover, about 70% of the GUS positive nodule-like structures from the incompatible interactions were localized at the junction between the tap and lateral roots. These observations are consistent with an atypical infection route by the incompatible strains.
The genic male-sterile rice (GMSR) sensitive to photoperiod during the panicle development period is a novel type of germplasm in rice, which is sterile under the long-day condition but fertile under the short-day condition. The fertility is also affected by temperature. A number of GMSR lines have been popularly used in commercial seed production of hybrid rice in China. Because the sterility is decided by environmental factors, a set of fertility conversion indices has been proposed to evaluate the usability and to determine the suitable regions for safe application of these male sterile lines. In the present experiment, 13 photoperiod-sensitive (PGMSR) lines that are dominant in China were sown by stages in the field at Hainan Island (18degrees 14' N), Quiyang (26degrees 35'N) and Wuhan (30degrees 38'N) in China. The fertility and sterility were distinguished on the percentage of seed-setting on the bagged panicles (PBS). The fertility conversion indices were determined on the day-length and temperature regimes and on a fertility quantifying model, and comparison was made between the two methods. Results showed that it was feasible to determine the fertility conversion index of GMSR lines based on data of bagged seed-setting rates in experiments of sowing at different times in the field. Of the 13 sterile lines observed, two of the PGMSR were found to be completely sterile when the length of the day exceeded 12.3 h. Five temperature-sensitive (TGMSR) lines had fertility conversion indices of 24 degreesC. One of the photoperiod- and temperature-sensitive (PTGMSR) lines showed that steady fertility conversion occurred under the short day in spite of high or low temperature. These GMSR lines are adaptable to the conditions of day-length and temperature in the main rice-growing regions of China and thus of high value in application to seed production.
The present study was carried out during 1996, 1997 and 1998 to estimate the additive, dominance and epistatic components of genetic variation for yield, yield components and wilt infection by using 90 triple test cross families and their parents, F-1 and F-2 in each of four sesame crosses, i.e. Bengalian x Giza 32 (TTC1), Intro 259 x Giza 25 (TTC2), Intro 413 x Intro 777 (TTC3) and Shandaweel 5 x Line 107 (TTC4). Mean squares from the genetic analysis of variance and the overall epistatic gene effects were highly significant differences for all studied characters. The [i] type (additive x additive) was the most important epistatic effect for height of the first capsule (TTC4), number of branches/plant (TTC1 and TTC3), length of the fruiting zone (TTC1, TTC2 and TTC3), days to the first flower and number of capsules/plant (TTC1, TTC2 and TTC4), 1000-seed (TTC3), wilt infection percentage (TTC3 and TTC4) and plant height, capsule length and seed yield/plant in all crosses. The ratio of (H/D)(1/2) confirmed the presence of partial dominance for all studied traits. The highest proportion of recombinant lines was obtained for days to the first flower, number of branches/plant, height of the first capsule and seed yield/plant in TTC3 and plant height, capsule length, length of the fruiting zone number of capsules/plant, 1000-seed weight and oil percentage in TTC2.
To identify separate effects of gender, castration and exogenous oestrogen on growth, castrated lambs of both sexes and entire male lambs (n = 8) were implanted subcutaneously with three sizes of oestradiol-17β implants, or not implanted, and grazed on ryegrass and white clover pasture for 180 days. A group of non-implanted entire female lambs (n = 8) was run together with the others. Non-implanted entire male lambs grew faster, had heavier heads, less internal, non-carcass fat and more protein and less fat and water in the carcass than non-implanted entire females. In addition, they had higher 12th vertebral spine, thicker tibia, and heavier and larger humerus than entire female lambs. Castration of male lambs reduced live-weight gain, weight of head and content of protein in the carcass whereas it increased carcass fat content. In addition, it caused lengthening of cannon bones and reduced height of 12th vertebral spine and length of tibia. In females, gonadectomy increased height of 12th vertebral spine and diameter to length ratio of the radius. Oestradiol treatment increased live-weight gain, reduced total internal and carcass fat, and increased water and protein content of the carcass in gonadectomized animals of either sex, and increased weight of carcass and head in spayed ewe lambs. Oestradiol treatment inhibited longitudinal growth of cannon bones and stimulated that of vertebral column and ribs, but had little effect on the dimensions of limb bones apart from increasing their diameter. Oestradiol treatment had no effect on muscle length but increased muscle girth and weight, except for m. splenius in ram lambs where muscle weight was reduced. Effects of oestradiol on skeletal measurements in most cases were linearly related to dose of oestradiol. It was concluded that the variable effects of sex steroids on the skeleton were related to the differential pattern of skeletal maturation. In early maturing bones acceleration of the growth process by an exogenous sex steroid caused elongation to cease prematurely, whereas in late-maturing bones the acceleration effect on elongation did not result in premature cessation. This observation may explain the often contradictory reports in the literature on the effects of sex steroids on linear growth of bone. [PUBLICATION ABSTRACT
Progress in politics and science often happens by accident. The unforeseen impact of the foot and mouth epidemic may fall into this category. Both the Ministry of Agriculture and vets were over-stretched dealing with the crisis and so badger culling, which was to have resumed on 1 May 2001, was suspended for a year; even routine TB testing of cattle is on hold. It seems probable that the Krebs/Bourne badger culling trial will be abandoned altogether. At least seven of the ten 'triplet' badger cull areas have been disrupted, particularly in Devon/Cornwall and Gloucestershire/Hereford. Some 600 of the 2900 badgers culled were in these two areas, perhaps 120 with TB, but only some 25 infectious. Since these were from some 400 km2, encompassing 450 farms, it is hard to see how the culls will have made the slightest impact on cattle TB. In fact it is already apparent that each TB badger has cost some £35000, which merely confirms the 1986 findings of the Dunnet Review that badger culls are a waste of money because they do not work. Professor McInerney, as part of the review, noted that ending badger culling was purely a political decision. If Labour had won the 1992 election, contingency plans were in place to end culls, but, sadly, by 1997 'New' Labour decided it was politically safer to go ahead with the Krebs cull. Enough data ought to be available from the trial to concoct 'scientific' reasons to grasp the nettle and take the inevitable and long overdue decision politically to end this sorry farce, once and for all. [PUBLICATION ABSTRACT