摘要:

AbstractSixty multiparous Holstein/Friesian cows were used in a 2 × 2 factorial design trial to determine the effect of the administration of bovine somatotropin (BST), at either 60 or 120 ± 3 d post partum, on milk production. All cows were offeredad libituma forage mixture containing, on a dry‐mailer (DM) basis, grass and maize silage in a 1:1 ratio and 4 kg d−1fresh weight of concentrate, which contained 115 and 495 g kg−1DM of neutral detergent fibre (NDF) and crude protein (CP), respectively, and 13–5 MJ kg−1DM metabolizable energy (ME). BST‐treated cows received subcutaneous injections of a prolonged‐release formulation of BST (sometribove). Injections were administered into the ischiorectal fossa at 14‐d intervals for the remainder of the lactation. This schedule resulted in sixteen and twelve injections cow−1when treatment w as in it rate d at 60 and 120 + 3 d post partum respectively. This corresponded to treatment periods of 32 and 24 weeks, in which the production responses were measured. When compared with control cows, the administration of BST from 60 and 120 ± 3 d post partum increased mean milk yield by 1–2 and 3.3 kg day−1respectively, although only the latter milk‐yield response was significant (P<0.001). The administration of BST produced a small nonsignificant increase in DM intake, no effect on milk composition and a small but significant reduction in body condition In conclusion a significant milk‐yield response can be obtained from the use of BST in high‐forage, low‐concentrate feeding systems if forage quality is high and treatment initiation is delayed until mid‐lactation. This is illustrated by the fact that the lactation yield increased from 6054 to 6842 kg. and was obtained wh

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02044.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractAn experiment was set up to investigate the morphological and physiological changes occurring in two white clover(Trifolium repens)(clover) varieties, AberHerald and Huia, growing in binary mixture with two perennial ryegrass(Lolium perenne)(grass) varieties, Preference and Ba 10761. Measurements were made on four occasions during winter/spring 1993–94. The statistical procedure of antedependence analysis was used to check for the existence of serial correlations among data from the different sampling dates. Evidence of antedependence was found in only three of the seventeen variables measured, and an order of antedependence for each of these was estimated. The antedependence structure providing the best fit to the data was then used in an analysis of covariance on the data set for that variable. The rest of the seventeen variables could be safely analysed by a split‐plot analysis of variance for each sampling date separately. This result validated the sampling protocol used in the experim

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02045.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractHigh (H; 27 350 m−1:) or low (L. 13 300 m‐1) tiller density perennial ryegrass swards were created in the mid‐ and late grazing season by imposing different sward heights in the spring. Summer‐calving cows then grazed these swards from 6 June to 2 September 1992 and were offered 5 kg fresh weight hd−1d−1of either a barley (S) or a molassed sugar beet pulp (F) based supplement. The factorial combination of sward and supplement types resulted in four experimental swards being grazed by thirteen Holstein/Friesian cows each.Supplement F contained more crude fibre (110 vs. 58 g kg−1) and less metabolizable energy [12–5 vs. 13–2 MJ kg−1dry matter (DM)] than supplement S. Herbage on the H sward contained more metabolizable energy (11–9 vs. 104 MJ kg−1DM) and crude protein (232 vs. 205 g kg−1DM), had fewer rejected areas f 16–5 vs. 26–9%) and a higher live‐dead tiller ratio (4–6 vs. 2–1) than that on the L sward.Sward, but not supplement type, significantly affected the intake of grazed herbage (P<0–001). On average, the herbage intakes of cows grazing II swards were higher than for L swards (14–5 vs. 11 6kg DM d−1) and those of cows on the S and F supplements were 12–6 and 13–5 kg DM d−1respectively. Averaged over the grazing period, sward and supplement had no significant effects on milk yield, milk composition or yield of constituents. When expressed on an average weekly basis, cows grazing an L sward and offered the F supplement on occasions had significantly lower milk yields and higher milk fat contents (P<005) than those grazing an H sward and offered the S supplement. There were no significant effects on cow live weight or condition score change. The results suggested that grazing swards with a high density of live tillers increased herbage intakes and on occasions milk yield, relative to low density swards. However, small increases in energy intake from sward and supplement effects we

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02046.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractAn experiment involving forty‐five British Friesian cows in mid‐late lactation was carried out to evaluate the effects of ensiling on herbage digestibility, dry‐matter intake and milk production. The herbage from the primary growth of a predominantly perennial ryegrass sward that had received 123 kg N ha−1was zero grazed (ZG) from 27 April to 24 May 1992. Before going onto the experimental diets all animals were offered a common silage as the sole diet and dry‐matter intakes and milk yields were recorded. The herbage was mown, picked‐up with a precision‐chop harvester and offered as the sole diet, twice daily, 10 fifteen cows that were on average 176 days into lactation. On May 20 herbage from the same sward was harvested identically to the ZG herbage and ensiled, alternative loads being untreated (UT) or treated with formic acid (2.4 l−1) (FA). For silages UT and FA respectively, pH values were 3.94 and 3.92 and ammonia nitrogen concentrations were 95 and 75 [g(kg total N−1)]. Forty‐two days after ensiling, the silages were fed twice daily as the sole diet to thirty cows which were on average 166 days into lactation. The feeding interval was 28 days and the last 7 days was the main recording period for each treatment. For diets ZG, UT and FA, dry‐matter intakes (DMI) (kg d−1), milk yields (kg d−1), fat plus protein yields (kg d−1). milk fat concentration (g kg−1), milk protein concentration (g kg−1)and fat plus protein yields [kg (kg DMI)−1] were 12.70, 11.51 and 12.07 (Av s.e.d. = 0.458); 12.79, 10.01 and 10.18 (Av s.e.d. = 0.346); 0.900, 0.649 and 0.682 (Av s.e.d. = 0.026); 39.8, 33.7 and 36.7 (Av s.e.d. = 0.174); 32.9, 29.9 and 30.0 (Av s.e.d. = 0.83); 0.073, 0.055 and 0.055 (Av s.e.d. = 0.003). UT treatment significantly increased dry matter (DM), organic matter (OM). energy and crude fibre digestibilities and the digestible OM concentration. UT and FA compared with ZG altered rumen fermentation patterns, significantly decreasing butyrate and increasing valerate concentrations. FA treatment significantly decreased the non‐glucogenic ratio. It is concluded that ensiling using formic acid had no effect on forage DMI relative to the parent fresh herbage. Ensiling either untreated or with formic acid significantly decreased milk yield and milk fat plus protein yield, resulting in a lower efficiency of convers

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02047.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractAn experiment was conducted to assess the effects of grazing a perennial ryegrass(Lolium perenne)/ white clover(Trifolium repens)sward by sheep or goats on sward composition and structure and on subsequent diet selection, herbage intake and liveweight gain by weaned lambs. From mid‐May to late July (phase 1), ewes with twin lambs or yearling Scottish Cashmere goats grazed continuously swards maintained at 4‐ or 8‐cm sward surface height. From mid‐August to the end of September (phase 2), weaned lambs continuously grazed the same swards maintained at 4 cm (treatment 4–4) or at 8 cm (treatment 8–8) or which had been allowed to increase from 4 cm to 8 cm (treatment 4–8). By the end of phase 1, swards grazed by goats had higher proportions of white clover in the whole sward (0.377 vs. 0.181; s.e.d 0.0382;P<0.001) than those grazed by sheep, irrespective of sward height treatment. This resulted in phase 2 in a higher proportion of white clover selected (P<0.001), higher herbage intakes (P<0.001) and higher liveweight gains (P<0.001) by weaned lambs grazing swards previously grazed by goats compared with those previously grazed by sheep. There were higher proportions of clover present in the swards from treatment 4–8 at the beginning of phase 2 compared with the other sward height treatments and consequently weaned lambs had, on this treatment, a higher proportion of clover in their diet (P<0.001), higher herbage intakes (P<0001) and higher liveweight gains (P<0.001). It is concluded that goats can be integrated into sequential grazing systems with sheep on grass/clover swards and this can result in an increase in the proportion of clover in swards and increased sh

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02048.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractIn an experiment, involving twelve male cattle (initially 235 kg live weight), the effects of applying lactic acid bacteria [Lactobacillus plantarum;109colony‐forming units (g fresh silage)−1] to grass silage, immediately prior to that silage being fed, on dry‐matter (DM) intake of the silage, degradability of nitrogen (N) and fibre in the rumen, total tract digestibility and composition of rumen fluid in the animals were examined. A grass silage, which had been made from the primary growth of a predominantly perennial ryegrass sward, was offered as the sole diet. The inoculant was applied to the silage at the rate of 2 g of freeze‐dried powder reconstituted in 12 ml of water (kg fresh silage)−1immediately prior to that silage being fed and an equivalent amount of water was applied to the silage in the control treatment. The two diets were compared in a change‐over design. The silage was well preserved, having a pH and concentrations of ammonia N and butyrate of 3.72, 74 g (kg total N)−1and 0.11 g (kg DM)−1respectively. Application of the inoculant significantly increased true protein, acid‐insoluble N and water‐soluble carbohydrate concentrations (P0.05) by inoculant treatment. It is concluded that application of the inoculant to the silage prior to silage being fed did not significantly affect silage DM intake, total tract digestibility, or degradability or fermentation in the rumen of cattle offered grass silage as the sole diet. It is also concluded that the results of this experiment provide no evidence that the mode of action ofL plantarum, applied as an additive to grass at ensiling in previous studies, is through ‘direct

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02049.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractInteractions between perennial ryegrass (grass) and white clover (clover) cultivars were investigated at the seedling stage in two experiments: (a) a field experiment in which two clovers, AberHerald and Grasslands Huia, were grown in binary mixture with two grasses, Preference and Ba 10761; (b) a glasshouse experiment in which the same clover/grass combinations were grown in low‐N soil either with (+ N) or without (‐N) added N. In the field experiment both clovers produced larger and more complex seedlings with Preference, and this was particularly evident in Huia. In the glasshouse experiment grass dry‐matter yield was greater in the +N treatment, and this effect increased with time. Clover seedling density and development were suppressed in the +N treatment, and the development of AberHerald was affected more than Huia. Morphological measurements of the clovers showed interactions between clover, grass and N level. In the ‐N treatment Huia plants were larger and more complex than those of AberHerald, but in +N conditions there was little difference between them. Grass cultivar had an effect on clover via N‐level interactions: in +N plants there was no grass effect, but ‐N plants were significantly larger with Preference. Comparison of the root and shoot morphology of the two grasses revealed no obvious differences that would account for th

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02050.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe effect of forage removal on the growth of five winter and five spring triticale genotypes was studied in 1992 and 1993 in field experiments in north‐eastern Spain. When cut, winter triticales produced more biomass and leaf area than spring types owing to their higher tillering capacity. The leaf area index (LAI) at anthesis was similar in both groups in both clipped and uncut plots, but spring triticales had a greater leaf area on the main stem than winter types. Winter types had a greater leaf area on the tillers than spring types. Spring and winter types had a similar physiological response to forage removal, except for modifications in flag leaf area. In spring types triticale flag leaf area was reduced by clipping, whereas in winter types flag leaf area was increased. Forage removal resulted in less dry‐matter accumulation in all plant parts, maximum weight of the plant being reduced by about 20% and the rate of growth by around 13%. LAI at anthesis decreased by 37% as a result of clipping, and the leaf area duration from anthesis to maturity decreased by 36%. The duration of growth increased after clipping. Heading, anthesis and maturity dates were delayed by clipping, but grain filling duration was not affec

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02051.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractThe effects of the imposition and timing of a rest period from continuous sheep stocking, for a conservation cut, on white clover presence in forty perennial ryegrass/white clover associations were studied over two full grazing seasons. Each association consisted of one grass variety along with one white clover variety, the grasses being diploid and tetraploid ryegrasses from each of five maturity groups and the white clovers from each of four leaf size categories. The presence of white clover within each association was assessed at the beginning and end of both seasons by means of a 0–64‐m2quadrat subdivided into 100 squares, each 80 mm × 80 mm, the number of squares in which any part of a white clover plant was visible being recorded. Complementary point quadrat data were also collected.Although continuous sheep stocking did not necessarily have an adverse effect on white clover presence, a July to mid‐August rest period increased white clover proportions in the swards (means: unrested, 48–1; April to late May rest, 32.7; July to mid‐August rest, 67.3 ‐ s.e.d. 7.59;P<0.05) the benefit increasing with increasing white clover leaf size. The early rest period (April to late May) reduced white clover presence and the late rest period (July to mid‐August) increased white clover presence, these effects being intensified with increasing white clover leaf size (very large‐leaved clover: unrested, 20.6; April to late May rest, 8.3;July to mid‐August rest, 41.1 and small‐leaved clover: unrested, 96.3; April to late May rest, 84.8; July to mid‐August rest, 97 ‐ s.e.d. 9.2;P<0001). Tetraploid ryegrass/white clover associations had consistently and significantly more white clover than diploid ryegrass/white clover associations of similar ryegrass maturity group (tetraploid, 53.4; diploid 44.8 ‐ s.e.d. 2.12;P<0.001) and associations with early maturing ryegrass contained more white clover than those with late maturing ryegrasses, the effect of maturity group being greater than that of ploidy. Overall, white clover presence increased with increasing open

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02052.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

AbstractIn Mediterranean drylands, drought survival is a major factor of persistence of perennial forage grasses. In the island of Corsica, plant survival and changes in water‐soluble carbohydrate (WSC) content were investigated in first‐ and second‐year swards of two populations of cocksfoot: Lutetia, a drought‐sensitive cultivar, and KM2, a drought‐resistant Mediterranean population. When subjected to a moderate drought under a rain‐shelter. Lutetia died whereas KM2 recovered with low mortality. The sensitivity of survival to the date of defoliation is emphasized. In first‐year swards, WSC content in entire tiller bases at the end of the drought was four times greater in KM2 than in Lutetia and was correlated with differential recovery in the two populations. Conversely in second‐year swards, no relationship between WSC content in entire tiller bases and recovery was found. However, WSC content in the youngest living enclosed leaves of KM2 accumulated to reach 63% of dry matter (DM) whereas in Lutetia WSC fell below 30% of DM; this factor might be associated with its survival. In both tiller bases and enclosed leaves, sucrose content and the content of large fructans tended to increase over the summer, whereas monosaccharide content declined. Enclosed leaves are the main survival organs: their role as a sink for translocated material (sucrose) and as a site of fructan accumulati

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1996.tb02053.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY