Renovation of pastures containing paspalum 1 . Persistence of overdrilled ryegrass and prairie grass and effect on seasonal pasture production

Thom, E. R.; Sheath, G. W.; Bryant, A. M.; Cox, N. R.

doi:10.1080/00288233.1986.10430451

Cited by 18 publications

(6 citation statements)

References 26 publications

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“…These figures are similar to those in Thom et al . (), who noted that large Nui perennial ryegrass plants (seventeen tillers) had a higher probability of surviving their first summer than small plants (ten tillers) growing in paspalum ( Paspalum dilatatum )‐dominant swards. This information regarding a threshold number of tillers per plant attained within the first few months of sward life may be a useful benchmark for evaluating establishment options for perennial ryegrass swards in the future.…”

Section: Discussionmentioning

confidence: 99%

High perennial ryegrass seeding rates reduce plant size and survival during the first year after sowing: does this have implications for pasture sward persistence?

Lee

Thom

Wynn

et al. 2016

Grass and Forage Science

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Failure of perennial ryegrass swards to persist is a key issue on dairy farms in many areas of the world. This study describes an experiment conducted to test the hypothesis that high ryegrass seeding rates (>18 kg seed ha À1 ) reduce plant size and physical survival during the first year after sowing, with negative implications for population persistence. Four cultivars representing four functional types of perennial ryegrass were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed ha À1 ) with white clover in three dairying regions of New Zealand. Plant establishment rates, size and survival were measured for the first 13 months after sowing. Herbage accumulation, botanical composition and perennial ryegrass tiller density were also monitored. Increasing seeding rate reduced plant survival in the seven weeks after sowing, reflecting likely differences in germination and very early mortality of small seedlings. Thereafter, plant survival was relatively high and consistent across seeding rates at two sites but was consistently greater in the 6 kg ha À1 treatment compared with the 24 and 30 kg ha À1 treatments at one site. Higher seeding rates also increased ryegrass tiller density and the contribution of ryegrass towards total herbage biomass but reduced the contribution of white clover. Very few cultivar 9 seeding rate interactions were detected for any of the measured variables. Many of the seeding rate effects dissipated by the end of the first year after sowing, indicating that high seeding rates did not predispose swards to poor persistence in the longer term, irrespective of ryegrass functional type.

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Section: Discussionmentioning

confidence: 99%

High perennial ryegrass seeding rates reduce plant size and survival during the first year after sowing: does this have implications for pasture sward persistence?

Lee

Thom

Wynn

et al. 2016

Grass and Forage Science

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“…Before calving, all heifers were grazed together and fresh pasture was allocated each morning. Pasture allocations were assessed visually and assessments were calibrated weekly through cutting a range of pasture yields representative of pre-and postgrazing yields (Thom et al, 1986). The DMI of each treatment was calculated daily from pregrazing and postgrazing pasture mass (Roche et al, 1996).…”

Section: Grazing Managementmentioning

confidence: 99%

Effect of Restricted Feeding and Monopropylene Glycol Postpartum on Metabolic Hormones and Postpartum Anestrus in Grazing Dairy Heifers

Chagas

Gore

Graham

et al. 2008

Journal of Dairy Science

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This study was designed to determine the effects of feed restriction and monopropylene glycol (MPG) supplementation on the reproductive, milk production, and somatotropic axes in dairy heifers postpartum. At calving, 49 Holstein-Friesian heifers were allowed either unrestricted (UNR; n = 18) or restricted access to pasture with (RES+MPG; n = 13) or without (RES; n = 18) MPG supplementation (250 mL drenched twice daily for 150 d). The average body condition score (BCS) of the heifers was 5.3 +/- 0.2 on a scale from 1 to 10 (where 1 = emaciated and 10 = obese). Body condition score and body weight were similar among the groups at calving and decreased after calving for all groups. However, body weight loss was around 10% greater for the RES and RES+MPG groups from wk 3 to 12 compared with UNR group. The length of the postpartum anestrous interval was similar for all groups (47, 51, and 45 +/- 5 d for the UNR, RES, and RES+MPG, respectively). Average milk production, protein, fat, and lactose yields during the first 12 wk postpartum were greater in the UNR group than in the RES and RES+MPG groups. Feed restriction affected plasma concentrations of insulin, with lower concentrations in the RES group compared with the UNR group. There were no differences in plasma concentrations of insulin between the RES+MPG group and the UNR or RES groups. An effect of feed restriction was observed on insulin-like growth factor-I concentrations and also a treatment by time interaction with a changing pattern through time as concentrations in the UNR group increased relative to the RES and RES+MPG groups. There were no differences in growth hormone concentrations among the groups. Glucose concentrations were lower in the RES group when compared with RES+MPG and UNR groups and this difference lessened over time. Plasma concentrations of nonesterified fatty acids were greater in the RES group compared with the RES+MPG and UNR groups. Leptin concentrations in the UNR group were greater than in the RES and RES+MPG groups. Hepatic growth hormone receptor 1A, total growth hormone receptor, and insulin-like growth factor-I relative mRNA expressions decreased postpartum with no effect of feed restriction, MPG supplementation, or interaction between time and treatment. During a challenge with MPG, insulin secretion was stimulated but no effect on postpartum anestrous interval in the treatment groups was observed. It was concluded that restricted pasture availability postpartum in dairy heifers calving in optimal BCS had no effect on the postpartum anestrous interval. It did however decrease milk production; thus, we can infer that monopropylene glycol supplementation does not act to prevent loss of milk yield.

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“…Pre-and post-grazing pasture mass was estimated daily on each area by calibrated visual assessment (Thom et al, 1986). Once each week, the pasture mass of 12 quadrats (each 0·33 m 2 ), representing the range of pre-and post-grazing pasture masses present on the experimental areas, were visually assessed, and the quadrats then cut to ground level with a portable shearing hand-piece.…”

Section: Experimental Measurementsmentioning

confidence: 99%

Responses to supplementation by dairy cows given low pasture allowances in different seasons 1. Pasture intake and substitution

Penno¹,

Macdonald²,

Holmes

et al. 2006

Anim. Sci.

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Two factorial experiments were designed to determine the effects of stage of lactation, and season of the year, on cow responses to supplementary feeding. These experiments were conducted over consecutive years with 128 high genetic merit multiparous Holstein-Friesian cows in early, mid and late lactation in spring, summer, autumn and winter. At each stage of lactation, and in each season of the year, cows were offered a restricted pasture allowance (25 to 35 kg dry matter (DM) per cow per day), either unsupplemented (control) or supplemented with 50 MJ metabolizable energy (ME) per cow per day in experiment 1 and 80 MJ ME per cow per day in experiment 2. Two different supplements were offered, namely, rolled maize grain (MG) and a mixture of foods (BR) formulated to nutritionally balance the diet. In experiment 2, a fourth treatment consisting solely of a generous pasture allowance (60 to 75 kg DM per cow per day, AP) was introduced. Offering MG and BR increased DM intake (DMI). At the restricted pasture allowance, increasing total ME allowance (MEA) by offering supplementary foods increased ME intake (MEI) by 0·68 (s.e. 0·047) MJ per extra MJ ME offered. This highly significant (P<0·001) linear relationship was consistent across seasons, and did not diminish at higher MEA. In experiment 2, cows in early lactation had lower substitution rates than mid and late lactation cows irrespective of season. Substitution rate was higher when higher pasture allowance or quality of pasture on offer enabled the unsupplemented cows to achieve higher DMI from pasture than at other times of the year. These results suggest that one of the key factors determining the intake response to supplementary foods is pasture allowance. Within spring calving dairying systems, the largest increases in total DMI per kg of supplement offered is likely when offering supplements to early lactation cows grazing restricted allowances of high quality pasture.

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Renovation of pastures containing paspalum 1 . Persistence of overdrilled ryegrass and prairie grass and effect on seasonal pasture production

Cited by 18 publications

References 26 publications

High perennial ryegrass seeding rates reduce plant size and survival during the first year after sowing: does this have implications for pasture sward persistence?

High perennial ryegrass seeding rates reduce plant size and survival during the first year after sowing: does this have implications for pasture sward persistence?

Effect of Restricted Feeding and Monopropylene Glycol Postpartum on Metabolic Hormones and Postpartum Anestrus in Grazing Dairy Heifers

Responses to supplementation by dairy cows given low pasture allowances in different seasons 1. Pasture intake and substitution

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