Four-Year Visual Outcomes in the Protocol W Randomized Trial of Intravitreous Aflibercept for Prevention of Vision-Threatening Complications of Diabetic Retinopathy

Importance

Anti-vascular endothelial growth factor (VEGF) injections in eyes with nonproliferative diabetic retinopathy (NPDR) without center-involved diabetic macular edema (CI-DME) reduce development of vision-threatening complications from diabetes over at least 2 years, but whether this treatment has a longer-term benefit on visual acuity is unknown.

Objective

To compare the primary 4-year outcomes of visual acuity and rates of vision-threatening complications in eyes with moderate to severe NPDR treated with intravitreal aflibercept compared with sham. The primary 2-year analysis of this study has been reported.

Design, Setting, and Participants

Randomized clinical trial conducted at 64 clinical sites in the US and Canada from January 2016 to March 2018, enrolling 328 adults (399 eyes) with moderate to severe NPDR (Early Treatment Diabetic Retinopathy Study [ETDRS] severity level 43-53; range, 0 [worst] to 100 [best]) without CI-DME.

Interventions

Eyes were randomly assigned to 2.0 mg aflibercept (n = 200) or sham (n = 199). Eight injections were administered at defined intervals through 2 years, continuing quarterly through 4 years unless the eye improved to mild NPDR or better. Aflibercept was given in both groups to treat development of high-risk proliferative diabetic retinopathy (PDR) or CI-DME with vision loss.

Main Outcomes and Measures

Development of PDR or CI-DME with vision loss (≥10 letters at 1 visit or ≥5 letters at 2 consecutive visits) and change in visual acuity (best corrected ETDRS letter score) from baseline to 4 years.

Results

Among participants (mean age 56 years; 42.4% female; 5% Asian, 15% Black, 32% Hispanic, 45% White), the 4-year cumulative probability of developing PDR or CI-DME with vision loss was 33.9% with aflibercept vs 56.9% with sham (adjusted hazard ratio, 0.40 [97.5% CI, 0.28 to 0.57]; P < .001). The mean (SD) change in visual acuity from baseline to 4 years was -2.7 (6.5) letters with aflibercept and -2.4 (5.8) letters with sham (adjusted mean difference, -0.5 letters [97.5% CI, -2.3 to 1.3]; P = .52). Antiplatelet Trialists' Collaboration cardiovascular/cerebrovascular event rates were 9.9% (7 of 71) in bilateral participants, 10.9% (14 of 129) in unilateral aflibercept participants, and 7.8% (10 of 128) in unilateral sham participants.

Conclusions and Relevance

Among patients with NPDR but without CI-DME at 4 years treatment with aflibercept vs sham, initiating aflibercept treatment only if vision-threatening complications developed, resulted in statistically significant anatomic improvement but no improvement in visual acuity. Aflibercept as a preventive strategy, as used in this trial, may not be generally warranted for patients with NPDR without CI-DME.

Trial Registration

ClinicalTrials.gov Identifier: NCT02634333.

Aflibercept Monotherapy or Bevacizumab First for Diabetic Macular Edema

BACKGROUND

In eyes with diabetic macular edema, the relative efficacy of administering aflibercept monotherapy as compared with bevacizumab first with a switch to aflibercept if the eye condition does not improve sufficiently (a form of step therapy) is unclear.

METHODS

At 54 clinical sites, we randomly assigned eyes in adults who had diabetic macular edema involving the macular center and a visual-acuity letter score of 24 to 69 (on a scale from 0 to 100, with higher scores indicating better visual acuity; Snellen equivalent, 20/320 to 20/50) to receive either 2.0 mg of intravitreous aflibercept or 1.25 mg of intravitreous bevacizumab. The drug was administered at randomization and thereafter according to the prespecified retreatment protocol. Beginning at 12 weeks, eyes in the bevacizumab-first group were switched to aflibercept therapy if protocol-specified criteria were met. The primary outcome was the mean change in visual acuity over the 2-year trial period. Retinal central subfield thickness and visual acuity at 2 years and safety were also assessed.

RESULTS

A total of 312 eyes (in 270 adults) underwent randomization; 158 eyes were assigned to receive aflibercept monotherapy and 154 to receive bevacizumab first. Over the 2-year period, 70% of the eyes in the bevacizumab-first group were switched to aflibercept therapy. The mean improvement in visual acuity was 15.0 letters in the aflibercept-monotherapy group and 14.0 letters in the bevacizumab-first group (adjusted difference, 0.8 letters; 95% confidence interval, -0.9 to 2.5; P = 0.37). At 2 years, the mean changes in visual acuity and retinal central subfield thickness were similar in the two groups. Serious adverse events (in 52% of the patients in the aflibercept-monotherapy group and in 36% of those in the bevacizumab-first group) and hospitalizations for adverse events (in 48% and 32%, respectively) were more common in the aflibercept-monotherapy group.

CONCLUSIONS

In this trial of treatment of moderate vision loss due to diabetic macular edema involving the center of the macula, we found no evidence of a significant difference in visual outcomes over a 2-year period between aflibercept monotherapy and treatment with bevacizumab first with a switch to aflibercept in the case of suboptimal response. (Funded by the National Institutes of Health; Protocol AC ClinicalTrials.gov number, NCT03321513.).

A Randomized Trial of Photobiomodulation Therapy for Center-Involved Diabetic Macular Edema with Good Visual Acuity (Protocol AE)

PURPOSE

To determine if treatment with a photobiomodulation (PBM) device results in greater improvement in central subfield thickness (CST) than placebo in eyes with center-involved diabetic macular edema (CI-DME) and good vision.

DESIGN

Phase 2 randomized clinical trial.

PARTICIPANTS

Participants had CI-DME and visual acuity (VA) 20/25 or better in the study eye and were recruited from 23 clinical sites in the United States.

METHODS

One eye of each participant was randomly assigned 1:1 to a 670-nm light-emitting PBM eye patch or an identical device emitting broad-spectrum white light at low power. Treatment was applied for 90 seconds twice daily for 4 months.

MAIN OUTCOME MEASURES

Change in CST on spectral-domain OCT at 4 months.

RESULTS

From April 2019 to February 2020, 135 adults were randomly assigned to either PBM (n = 69) or placebo (n = 66); median age was 62 years, 37% were women, and 82% were White. The median device compliance was 92% with PBM and 95% with placebo. OCT CST increased from baseline to 4 months by a mean (SD) of 13 (53) μm in PBM eyes and 15 (57) μm in placebo eyes, with the mean difference (95% confidence interval [CI]) being -2 (-20 to 16) μm (P = 0.84). CI-DME, based on DRCR Retina Network sex- and machine-based thresholds, was present in 61 (90%) PBM eyes and 57 (86%) placebo eyes at 4 months (adjusted odds ratio [95% CI] = 1.30 (0.44-3.83); P = 0.63). VA decreased by a mean (SD) of -0.2 (5.5) letters and -0.6 (4.6) letters in the PBM and placebo groups, respectively (difference [95% CI] = 0.4 (-1.3 to 2.0) letters; P = 0.64). There were 8 adverse events possibly related to the PBM device and 2 adverse events possibly related to the placebo device. None were serious.

CONCLUSIONS

PBM as given in this study, although safe and well-tolerated, was not found to be effective for the treatment of CI-DME in eyes with good vision.

Lapses in Care Among Patients Assigned to Ranibizumab for Proliferative Diabetic Retinopathy: A Post Hoc Analysis of a Randomized Clinical Trial

Importance

The follow-up schedule for individuals with eyes treated with anti-vascular endothelial growth factor agents for proliferative diabetic retinopathy (PDR) requires that patients return frequently for monitoring and repeated treatment. The likelihood that a patient will comply should be a consideration in choosing a treatment approach.

Objective

To describe completion of scheduled examinations among participants assigned to intravitreous injections of ranibizumab for PDR in a multicenter randomized clinical trial.

Design, Setting, and Participants

This post hoc analysis evaluates data from a randomized clinical trial conducted at 55 US sites among 305 adults with proliferative diabetic retinopathy enrolled between February and December 2012. Both eyes were enrolled for 89 participants (1 eye to each study group), with a total of 394 study eyes. The final 2-year visit was completed in January 2015. Data were analyzed from April 2019 to July 2021.

Interventions

Ranibizumab injections for PDR or macular edema.

Main Outcomes and Measures

A long lapse in care of 8 or more weeks past a scheduled examination, dropout from follow-up, visual acuity at 5 years.

Results

Among 170 participants, the median age was 51 years, and 44.7% were female. Through 5 years of follow-up, 94 of 170 participants (55.3%) had 1 or more long lapse in care. Median time to the first long lapse was 210 weeks, and 69 of 94 participants (73.4%) returned for examination after the first long lapse. Fifty of 170 participants (29.4%) dropped out of follow-up by 5 years. Among the 120 participants who completed the 5-year examination, median change from baseline in visual acuity was -2 letters for participants who had 1 or more long lapse compared with +5 letters for those without a long lapse (P = .02). After multivariable adjustment, the odds ratio (95% CI) for baseline associations with 1 or more long lapse was 1.21 (1.03-1.43) for each 5-letter decrement in visual acuity score, 2.19 (1.09-4.38) for neovascularization of the disc and elsewhere, and 3.48 (1.38-8.78) for no prior laser treatment for diabetic macular edema.

Conclusions and Relevance

Over 5 years, approximately half of the participants assigned to ranibizumab for PDR had a long lapse in care despite substantial effort by the DRCR Retina Network to facilitate timely completion of examinations. The likelihood of a long lapse in care during long-term follow-up needs to be considered when choosing treatment for PDR.

Trial Registration

ClinicalTrials.gov Identifier: NCT01489189.

Effect of Intravitreous Anti-Vascular Endothelial Growth Factor vs Sham Treatment for Prevention of Vision-Threatening Complications of Diabetic Retinopathy: The Protocol W Randomized Clinical Trial

Importance

The role of anti-vascular endothelial growth factor injections for the management of nonproliferative diabetic retinopathy (NPDR) without center-involved diabetic macular edema (CI-DME) has not been clearly established.

Objective

To determine the efficacy of intravitreous aflibercept injections compared with sham treatment in preventing potentially vision-threatening complications in eyes with moderate to severe NPDR.

Design, Setting, and Participants

Data for this study were collected between January 15, 2016, and May 28, 2020, from the ongoing DRCR Retina Network Protocol W randomized clinical trial, conducted at 64 US and Canadian sites among 328 adults (399 eyes) with moderate to severe NPDR (Early Treatment Diabetic Retinopathy Study severity level, 43-53), without CI-DME. Analyses followed the intent-to-treat principle.

Interventions

Eyes were randomly assigned to 2.0 mg of aflibercept injections (n = 200) or sham (n = 199) given at baseline; 1, 2, and 4 months; and every 4 months through 2 years. Between 2 and 4 years, treatment was deferred if the eye had mild NPDR or better. Aflibercept was administered in both groups if CI-DME with vision loss (≥10 letters at 1 visit or 5-9 letters at 2 consecutive visits) or high-risk proliferative diabetic retinopathy (PDR) developed.

Main Outcomes and Measures

Development of CI-DME with vision loss or PDR through May 2020, when the last 2-year visit was completed.

Results

Among the 328 participants (57.6% men [230 of 399 eyes]; mean [SD] age, 56 [11] years), the 2-year cumulative probability of developing CI-DME with vision loss or PDR was 16.3% with aflibercept vs 43.5% with sham. The overall hazard ratio for either outcome was 0.32 (97.5% CI, 0.21-0.50; P < .001), favoring aflibercept. The 2-year cumulative probability of developing PDR was 13.5% in the aflibercept group vs 33.2% in the sham group, and the 2-year cumulative probability of developing CI-DME with vision loss was 4.1% in the aflibercept group vs 14.8% in the sham group. The mean (SD) change in visual acuity from baseline to 2 years was -0.9 (5.8) letters with aflibercept and -2.0 (6.1) letters with sham (adjusted mean difference, 0.5 letters [97.5% CI, -1.0 to 1.9 letters]; P = .47).

Conclusions and Relevance

In this randomized clinical trial, among eyes with moderate to severe NPDR, the proportion of eyes that developed PDR or vision-reducing CI-DME was lower with periodic aflibercept compared with sham treatment. However, through 2 years, preventive treatment did not confer visual acuity benefit compared with observation plus treatment with aflibercept only after development of PDR or vision-reducing CI-DME. The 4-year results will be important to assess longer-term visual acuity outcomes.

Trial Registration

ClinicalTrials.gov Identifier: NCT02634333.

Effect of Intravitreous Aflibercept vs Vitrectomy With Panretinal Photocoagulation on Visual Acuity in Patients With Vitreous Hemorrhage From Proliferative Diabetic Retinopathy: A Randomized Clinical Trial

IMPORTANCE

Vitreous hemorrhage from proliferative diabetic retinopathy can cause loss of vision. The best management approach is unknown.

OBJECTIVE

To compare initial treatment with intravitreous aflibercept vs vitrectomy with panretinal photocoagulation for vitreous hemorrhage from proliferative diabetic retinopathy.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial at 39 DRCR Retina Network sites in the US and Canada including 205 adults with vison loss due to vitreous hemorrhage from proliferative diabetic retinopathy who were enrolled from November 2016 to December 2017. The final follow-up visit was completed in January 2020.

INTERVENTIONS

Random assignment of eyes (1 per participant) to aflibercept (100 participants) or vitrectomy with panretinal photocoagulation (105 participants). Participants whose eyes were assigned to aflibercept initially received 4 monthly injections. Both groups could receive aflibercept or vitrectomy during follow-up based on protocol criteria.

MAIN OUTCOMES AND MEASURES

The primary outcome was mean visual acuity letter score (range, 0-100; higher scores indicate better vision) over 24 weeks (area under the curve); the study was powered to detect a difference of 8 letters. Secondary outcomes included mean visual acuity at 4 weeks and 2 years.

RESULTS

Among 205 participants (205 eyes) who were randomized (mean [SD] age, 57 [11] years; 115 [56%] men; mean visual acuity letter score, 34.5 [Snellen equivalent, 20/200]), 95% (195 of 205) completed the 24-week visit and 90% (177 of 196, excluding 9 deaths) completed the 2-year visit. The mean visual acuity letter score over 24 weeks was 59.3 (Snellen equivalent, 20/63) (95% CI, 54.9 to 63.7) in the aflibercept group vs 63.0 (Snellen equivalent, 20/63) (95% CI, 58.6 to 67.3) in the vitrectomy group (adjusted difference, -5.0 [95% CI, -10.2 to 0.3], P = .06). Among 23 secondary outcomes, 15 showed no significant difference. The mean visual acuity letter score was 52.6 (Snellen equivalent, 20/100) in the aflibercept group vs 62.3 (Snellen equivalent, 20/63) in the vitrectomy group at 4 weeks (adjusted difference, -11.2 [95% CI, -18.5 to -3.9], P = .003) and 73.7 (Snellen equivalent, 20/40) vs 71.0 (Snellen equivalent, 20/40) at 2 years (adjusted difference, 2.7 [95% CI, -3.1 to 8.4], P = .36). Over 2 years, 33 eyes (33%) assigned to aflibercept received vitrectomy and 34 eyes (32%) assigned to vitrectomy received subsequent aflibercept.

CONCLUSIONS AND RELEVANCE

Among participants whose eyes had vitreous hemorrhage from proliferative diabetic retinopathy, there was no statistically significant difference in the primary outcome of mean visual acuity letter score over 24 weeks following initial treatment with intravitreous aflibercept vs vitrectomy with panretinal photocoagulation. However, the study may have been underpowered, considering the range of the 95% CI, to detect a clinically important benefit in favor of initial vitrectomy with panretinal photocoagulation.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02858076.

Visual Field Changes Over 5 Years in Patients Treated With Panretinal Photocoagulation or Ranibizumab for Proliferative Diabetic Retinopathy

Importance

Preservation of peripheral visual field (VF) is considered an advantage for anti-vascular endothelial growth factor agents compared with panretinal photocoagulation (PRP) for treatment of proliferative diabetic retinopathy. Long-term data on VF are important when considering either treatment approach.

Objective

To further evaluate changes in VF throughout 5 years among eyes enrolled in the Protocol S clinical trial, conducted by the DRCR Retina Network.

Design, Setting, and Participants

Post hoc analyses of an ancillary study within a multicenter (55 US sites) randomized clinical trial. Individuals with eyes with proliferative diabetic retinopathy enrolled in Protocol S were included. Data were collected from February 2012 to February 2018. Analysis began in June 2018.

Interventions

Panretinal photocoagulation or intravitreous injections of 0.5-mg ranibizumab. Diabetic macular edema, whenever present, was treated with ranibizumab in both groups. Panretinal photocoagulation could be administered to eyes in the ranibizumab group when failure or futility criteria were met.

Main Outcomes and Measures

Mean change in total point score on VF testing with the Humphrey Field Analyzer 30-2 and 60-4 test patterns.

Results

Of 394 eyes enrolled in Protocol S, 234 (59.4%) were targeted for this ancillary study. Of these, 167 (71.4%) had VF meeting acceptable quality criteria at baseline (median [interquartile range] age, 50 [43-58] years; 90 men [53.9%]). At 5 years, 79 (33.8%) had results available. The mean (SD) change in total point score in the PRP and ranibizumab groups was -305 (521) dB and -36 (486) dB at 1 year, respectively, increasing to -527 (635) dB and -330 (645) dB at 5 years, respectively (P = .04). After censoring VF results after PRP treatments in the ranibizumab group, the 5-year mean change in total point score was -201 (442) dB. In a longitudinal regression analysis of change in total point score including both treatment groups, laser treatment was associated with a mean point decrease of 208 (95% CI, 112-304) dB for the initial PRP session, 77 (95% CI, 21-132) dB for additional PRP sessions, and 325 (95% CI, 211-439) dB for endolaser. No association was found between change in point score and the number of ranibizumab injections during the previous year (-9 per injection [95% CI, -22 to 3]).

Conclusions and Relevance

The limited data available from Protocol S suggest that there are factors besides PRP associated with VF loss in eyes treated for proliferative diabetic retinopathy. Further clinical research is warranted to clarify the finding.

Trial Registration

ClinicalTrials.gov identifier: NCT01489189.

Assessment of the DRCR Retina Network Approach to Management With Initial Observation for Eyes With Center-Involved Diabetic Macular Edema and Good Visual Acuity: A Secondary Analysis of a Randomized Clinical Trial

Importance

Among eyes with center-involved diabetic macular edema (CI-DME) and good visual acuity (VA), randomized clinical trial results showed no difference in VA loss between initial observation plus aflibercept only if VA decreased, initial focal/grid laser plus aflibercept only if VA decreased, or prompt aflibercept. Understanding the initial observation approach is relevant to patient management.

Objective

To assess the DRCR Retina Network protocol-defined approach and outcomes of initial observation with aflibercept only if VA worsened.

Design, Setting, and Participants

This was a post hoc secondary analyses of a randomized clinical trial of the DRCR Retina Network Protocol V that included 91 US and Canadian sites from November 2013 to September 2018. Participants were adults (n = 236) with type 1 or 2 diabetes, 1 study eye with CI-DME, and VA letter score at least 79 (Snellen equivalent, 20/25 or better) assigned to initial observation. Data were analyzed from March 2019 to November 2019.

Interventions

Initial observation and follow-up with aflibercept only for VA loss of at least 10 letters from baseline at 1 visit or 5 to 9 letters at 2 consecutive visits. Follow-up occurred at 8 weeks and then every 16 weeks unless VA or optical coherence tomography central subfield thickness worsened.

Main Outcomes and Measures

Whether individuals received aflibercept.

Results

Among 236 eyes in 236 individuals (149 [63%] male; median age, 60 years [interquartile range, 53-67 years]) randomly assigned to initial observation, 80 (34%) were treated with aflibercept during 2 years of follow-up. At 2 years, the median VA letter score was 86.0 (interquartile range, 89.0-81.0; median Snellen equivalent, 20/20 [20/16-20/25]). Receipt of aflibercept was more likely in eyes with baseline central subfield thickness at least 300 μm (Zeiss-Stratus equivalent) vs less than 300 μm (45% vs 26%; hazard ratio [HR], 1.98 [95% CI, 1.26-3.13], continuous P = .005), moderately severe nonproliferative diabetic retinopathy (Early Treatment Diabetic Retinopathy Study retinopathy severity level 47) and above vs moderate nonproliferative diabetic retinopathy (retinopathy severity level 43) and below (51% vs 27%; HR, 2.22 [95% CI, 1.42-3.47], ordinal P < .001), and among participants whose nonstudy eye received DME treatment within 4 months of randomization vs not (52% vs 25%; HR, 2.55 [95% CI, 1.64-3.99], P < .001).

Conclusions and Relevance

Most eyes managed with initial observation plus aflibercept only if VA worsened maintained good vision at 2 years and did not require aflibercept for VA loss. However, the eyes in the trial were approximately twice as likely to receive aflibercept for VA loss if they had greater baseline central subfield thickness, worse diabetic retinopathy severity level, or a nonstudy eye receiving treatment for DME.

Trial Registration

ClinicalTrials.gov Identifier: NCT01909791.

Effect of telephone calls from a centralized coordinating center on participant retention in a randomized clinical trial

BACKGROUND/AIMS

In clinical trials, participant retention is critical to reduce bias and maintain statistical power for hypothesis testing. Within a multi-center clinical trial of diabetic retinopathy, we investigated whether regular phone calls to participants from the coordinating center improved long-term participant retention.

METHODS

Among 305 adults in the Diabetic Retinopathy Clinical Research Retina Network Protocol S randomized trial, 152 participants were randomly assigned to receive phone calls at baseline, 6 months, and annually through 3 years (annual contact group) while 153 participants were assigned to receive a phone call at baseline only (baseline contact group). All participants could be contacted if visits were missed. The main outcomes were visit completion, excluding deaths, at 2 years (the primary outcome time point) and at 5 years (the final time point).

RESULTS

At baseline, 77% (117 of 152) of participants in the annual contact group and 76% (116 of 153) in the baseline contact group were successfully contacted. Among participants in the annual contact group active at each annual visit (i.e. not dropped from the study or deceased), 85% (125 of 147), 79% (108 of 136), and 88% (110 of 125) were contacted successfully by telephone around the time of the 1-, 2-, and 3-year visits, respectively. In the annual and baseline contact groups, completion rates for the 2-year primary outcome visit were 88% (129 of 147) versus 87% (125 of 144), respectively, with a risk ratio of 1.01 (95% confidence interval: 0.93-1.10, p = .81). At 5 years, the final study visit, participant completion rates were 67% (96 of 144) versus 66% (88 of 133) with a risk ratio of 1.01 (95% confidence interval = 0.85-1.19, p = .93). At 2 years, the completion rate of participants successfully contacted at baseline was 89% (202 of 226) versus 80% (52 of 65) among those not contacted successfully (risk ratio = 1.12, 95% confidence interval = 0.98-1.27, p = .09); at 5 years, the completion percentages by baseline contact success were 69% (148 of 213) versus 56% (36 of 64; risk ratio = 1.24, 95% confidence interval = 0.98-1.56, p = .08).

CONCLUSION

Regular phone calls from the coordinating center to participants during follow-up in this randomized clinical trial did not improve long-term participant retention.

Five-Year Outcomes of Panretinal Photocoagulation vs Intravitreous Ranibizumab for Proliferative Diabetic Retinopathy: A Randomized Clinical Trial

Importance

Ranibizumab is a viable treatment option for eyes with proliferative diabetic retinopathy (PDR) through 2 years. However, longer-term results are needed.

Objective

To evaluate efficacy and safety of 0.5-mg intravitreous ranibizumab vs panretinal photocoagulation (PRP) over 5 years for PDR.

Design, Setting, and Participants

Diabetic Retinopathy Clinical Research Network multicenter randomized clinical trial evaluated 394 study eyes with PDR enrolled February through December 2012. Analysis began in January 2018.

Interventions

Eyes were randomly assigned to receive intravitreous ranibizumab (n = 191) or PRP (n = 203). Frequency of ranibizumab was based on a protocol-specified retreatment algorithm. Diabetic macular edema could be managed with ranibizumab in either group.

Main Outcomes and Measures

Mean change in visual acuity (intention-to-treat analysis) was the main outcome. Secondary outcomes included peripheral visual field loss, development of vision-impairing diabetic macular edema, and ocular and systemic safety.

Results

The 5-year visit was completed by 184 of 277 participants (66% excluding deaths). Of 305 enrolled participants, the mean (SD) age was 52 (12) years, 135 (44%) were women, and 160 (52%) were white. For the ranibizumab and PRP groups, the mean (SD) number of injections over 5 years was 19.2 (10.9) and 5.4 (7.9), respectively; the mean (SD) change in visual acuity letter score was 3.1 (14.3) and 3.0 (10.5) letters, respectively (adjusted difference, 0.6; 95% CI, -2.3 to 3.5; P = .68); the mean visual acuity was 20/25 (approximate Snellen equivalent) in both groups at 5 years. The mean (SD) change in cumulative visual field total point score was -330 (645) vs -527 (635) dB in the ranibizumab (n = 41) and PRP (n = 38) groups, respectively (adjusted difference, 208 dB; 95% CI, 9-408). Vision-impairing diabetic macular edema developed in 27 and 53 eyes in the ranibizumab and PRP groups, respectively (cumulative probabilities: 22% vs 38%; hazard ratio, 0.4; 95% CI, 0.3-0.7). No statistically significant differences between groups in major systemic adverse event rates were identified.

Conclusions and Relevance

Although loss to follow-up was relatively high, visual acuity in most study eyes that completed follow-up was very good at 5 years and was similar in both groups. Severe vision loss or serious PDR complications were uncommon with PRP or ranibizumab; however, the ranibizumab group had lower rates of developing vision-impairing diabetic macular edema and less visual field loss. Patient-specific factors, including anticipated visit compliance, cost, and frequency of visits, should be considered when choosing treatment for patients with PDR. These findings support either anti-vascular endothelial growth factor therapy or PRP as viable treatments for patients with PDR.

Trial Registration

ClinicalTrials.gov Identifier: NCT01489189.

Effect of Initial Management With Aflibercept vs Laser Photocoagulation vs Observation on Vision Loss Among Patients With Diabetic Macular Edema Involving the Center of the Macula and Good Visual Acuity: A Randomized Clinical Trial

IMPORTANCE

Intravitreous injections of antivascular endothelial growth factor agents are effective for treating diabetic macular edema (DME) involving the center of the macula (center-involved DME [CI-DME]) with visual acuity impairment (20/32 or worse). The best approach to treating patients with CI-DME and good visual acuity (20/25 or better) is unknown.

OBJECTIVE

To compare vision loss at 2 years among eyes initially managed with aflibercept, laser photocoagulation, or observation.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial conducted at 91 US and Canadian sites among 702 adults with type 1 or type 2 diabetes. Participants had 1 study eye with CI-DME and visual acuity of 20/25 or better. The first participant was randomized on November 8, 2013, and the final date of follow-up was September 11, 2018.

INTERVENTIONS

Eyes were randomly assigned to 2.0 mg of intravitreous aflibercept (n = 226) as frequently as every 4 weeks, focal/grid laser photocoagulation (n = 240), or observation (n = 236). Aflibercept was required for eyes in the laser photocoagulation or observation groups that had decreased visual acuity from baseline by at least 10 letters (≥ 2 lines on an eye chart) at any visit or by 5 to 9 letters (1-2 lines) at 2 consecutive visits.

MAIN OUTCOMES AND MEASURES

The primary outcome was at least a 5-letter visual acuity decrease from baseline at 2 years. Antiplatelet Trialists' Collaboration adverse events (defined as myocardial infarction, stroke, or vascular or unknown death) were reported.

RESULTS

Among 702 randomized participants (mean age, 59 years; 38% female [n=264]), 625 of 681 (92% excluding deaths) completed the 2-year visit. For eyes with visual acuity that decreased from baseline, aflibercept was initiated in 25% (60/240) and 34% (80/236) in the laser photocoagulation and observation groups, respectively. At 2 years, the percentage of eyes with at least a 5-letter visual acuity decrease was 16% (33/205), 17% (36/212), and 19% (39/208) in the aflibercept, laser photocoagulation, and observation groups, respectively (aflibercept vs laser photocoagulation risk difference, -2% [95% CI, -9% to 5%]; relative risk, 0.88 [95% CI, 0.57-1.35; P = .79]; aflibercept vs observation risk difference, -3% [95% CI, -11% to 4%]; relative risk, 0.83 [95% CI, 0.55-1.27; P = .79]; laser photocoagulation vs observation risk difference, -1% [95% CI, -9% to 6%]; relative risk, 0.95 [95% CI, 0.64-1.41; P = .79]). Antiplatelet Trialists' Collaboration vascular events occurred in 15 (7%), 13 (5%), and 8 (3%) participants in the aflibercept, laser photocoagulation, and observation groups.

CONCLUSIONS AND RELEVANCE

Among eyes with CI-DME and good visual acuity, there was no significant difference in vision loss at 2 years whether eyes were initially managed with aflibercept or with laser photocoagulation or observation and given aflibercept only if visual acuity worsened. Observation without treatment unless visual acuity worsens may be a reasonable strategy for CI-DME.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01909791.

Rationale and Application of the Protocol S Anti-Vascular Endothelial Growth Factor Algorithm for Proliferative Diabetic Retinopathy

PURPOSE

To present the rationale, guidelines, and results of ranibizumab treatment for proliferative diabetic retinopathy (PDR) in Diabetic Retinopathy Clinical Research Network (DRCR.net) Protocol S.

DESIGN

Post hoc analyses from a randomized clinical trial.

PARTICIPANTS

Three hundred five participants (394 study eyes) having PDR without prior panretinal photocoagulation (PRP).

METHODS

Intravitreous ranibizumab (0.5 mg) versus PRP for PDR. Ranbizumab-assigned eyes (n = 191) received monthly injections for 6 months unless resolution was achieved after 4 injections. After 6 months, injections could be deferred if neovascularization was stable over 3 consecutive visits (sustained stability). If neovascularization worsened, monthly treatment resumed. Panretinal photocoagulation could be initiated for failure or futility criteria.

MAIN OUTCOME MEASURES

Neovascularization status through 2 years.

RESULTS

At 1 month, 19% (35 of 188) of ranibizumab-assigned eyes showed complete neovascularization resolution and an additional 60% (113) showed improvement. At 6 months, 52% (80 of 153) showed neovascularization resolution, 3% (4) were improved, 37% (56) were stable, and 8% (13) had worsened since the last visit. Among eyes with versus without resolved neovascularization at 6 months, the median (interquartile range) number of injections between 6 months and 2 years was 4 (1-7; n = 73) versus 7 (4-11; n = 67; P < 0.001). Injections were deferred in 68 of 73 eyes (93%) meeting sustained stability at least once during the study; 62% (42 of 68) resumed injections within 16 weeks after deferral. At 2 years, 43% (66 of 154) showed neovascularization resolution, 5% (7) showed improvement, 23% (36) were stable, and 27% (42) had worsened since the last visit. Only 3 eyes met criteria for failure or futility through 2 years.

CONCLUSIONS

The DRCR.net treatment algorithm for PDR can provide excellent clinical outcomes through 2 years for patients initiating anti-vascular endothelial growth factor (VEGF) therapy for PDR. When choosing between anti-VEGF and PRP as first-line therapy for PDR, treatment decisions should be guided by consideration of the relative advantages of each therapeutic method and anticipated patient compliance with follow-up and treatment recommendations.

Elimination of Topical Antibiotics for Intravitreous Injections and the Importance of Using Povidone-Iodine: Update From the Diabetic Retinopathy Clinical Research Network

Importance

This report provides updated endophthalmitis rates for eyes receiving intravitreous injections with and without povidone-iodine and rates with and without topical antibiotics from Diabetic Retinopathy Clinical Research Network clinical trials.

Observations

Among 8 Diabetic Retinopathy Clinical Research Network clinical trials conducted from 2006 to 2015, 28 786 intravitreous injections were administered (3123 eyes), and 20 617 of those (2264 eyes) were administered between 2012 and 2015. Eleven cases of endophthalmitis occurred; 4 occurred between 2012 and 2015. Thirteen injections in 3 eyes from 2 participants were administered without povidone-iodine; both participants developed endophthalmitis in 1 eye. Of the remaining 28 773 injections (3120 eyes) performed with povidone-iodine, 9 cases of endophthalmitis occurred: 6 cases (0.05% of 11 565 injections) in eyes receiving topical antibiotics and 3 cases (0.02% of 17 208 injections) in eyes not receiving topical antibiotics (P = .17).

Conclusions and Relevance

While only a small number of eyes did not receive povidone-iodine just prior to an intravitreous injection, this report provides further evidence regarding the risk of endophthalmitis when povidone-iodine is not used before intravitreous injections. Exclusion of topical antibiotics was not associated with a higher risk of endophthalmitis. Continued use of povidone-iodine and consideration to eliminate topical antibiotics from injection procedures seems warranted.

Panretinal Photocoagulation vs Intravitreous Ranibizumab for Proliferative Diabetic Retinopathy: A Randomized Clinical Trial

IMPORTANCE

Panretinal photocoagulation (PRP) is the standard treatment for reducing severe visual loss from proliferative diabetic retinopathy. However, PRP can damage the retina, resulting in peripheral vision loss or worsening diabetic macular edema (DME).

OBJECTIVE

To evaluate the noninferiority of intravitreous ranibizumab compared with PRP for visual acuity outcomes in patients with proliferative diabetic retinopathy.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial conducted at 55 US sites among 305 adults with proliferative diabetic retinopathy enrolled between February and December 2012 (mean age, 52 years; 44% female; 52% white). Both eyes were enrolled for 89 participants (1 eye to each study group), with a total of 394 study eyes. The final 2-year visit was completed in January 2015.

INTERVENTIONS

Individual eyes were randomly assigned to receive PRP treatment, completed in 1 to 3 visits (n = 203 eyes), or ranibizumab, 0.5 mg, by intravitreous injection at baseline and as frequently as every 4 weeks based on a structured re-treatment protocol (n = 191 eyes). Eyes in both treatment groups could receive ranibizumab for DME.

MAIN OUTCOMES AND MEASURES

The primary outcome was mean visual acuity change at 2 years (5-letter noninferiority margin; intention-to-treat analysis). Secondary outcomes included visual acuity area under the curve, peripheral visual field loss, vitrectomy, DME development, and retinal neovascularization.

RESULTS

Mean visual acuity letter improvement at 2 years was +2.8 in the ranibizumab group vs +0.2 in the PRP group (difference, +2.2; 95% CI, -0.5 to +5.0; P < .001 for noninferiority). The mean treatment group difference in visual acuity area under the curve over 2 years was +4.2 (95% CI, +3.0 to +5.4; P < .001). Mean peripheral visual field sensitivity loss was worse (-23 dB vs -422 dB; difference, 372 dB; 95% CI, 213-531 dB; P < .001), vitrectomy was more frequent (15% vs 4%; difference, 9%; 95% CI, 4%-15%; P < .001), and DME development was more frequent (28% vs 9%; difference, 19%; 95% CI, 10%-28%; P < .001) in the PRP group vs the ranibizumab group, respectively. Eyes without active or regressed neovascularization at 2 years were not significantly different (35% in the ranibizumab group vs 30% in the PRP group; difference, 3%; 95% CI, -7% to 12%; P = .58). One eye in the ranibizumab group developed endophthalmitis. No significant differences between groups in rates of major cardiovascular events were identified.

CONCLUSIONS AND RELEVANCE

Among eyes with proliferative diabetic retinopathy, treatment with ranibizumab resulted in visual acuity that was noninferior to (not worse than) PRP treatment at 2 years. Although longer-term follow-up is needed, ranibizumab may be a reasonable treatment alternative, at least through 2 years, for patients with proliferative diabetic retinopathy.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01489189.

Evaluation of masking study participants to intravitreal injections in a randomized clinical trial

OBJECTIVE

To evaluate the success of masking study participants to treatment allocation using sham intravitreal injections.

METHODS

Eyes were randomized to receive sham injections plus prompt laser, intravitreal ranibizumab injections plus prompt laser, intravitreal ranibizumab injections plus deferred laser, or intravitreal triamcinolone acetonide injections plus prompt laser up to every 16 weeks with sham injections intermittently. All eyes could receive treatment or sham as often as every 4 weeks. Participants with 2 study eyes had 1 eye randomized to sham plus prompt laser and 1 eye randomized to a real injection group. Sham injections were performed by pressing the syringe hub against the conjunctiva to mimic a real injection. Laser treatment was not masked. At the 1-year visit, participants were asked if they believed that the injections received during the study were real, sham, or sometimes real and sometimes sham.

RESULTS

Among 423 participants with 1 study eye, the correct assignment was stated by 9.9% of the sham plus prompt laser group, 88.0% of the ranibizumab plus prompt laser group, 89.6% of the unmasked ranibizumab plus deferred laser group, and 44.0% of the triamcinolone plus prompt laser group. Among 112 participants with 2 study eyes, the correct assignment was stated for 24.1% of the sham plus prompt laser eyes.

CONCLUSIONS

Successful masking of an intravitreal injection can be accomplished when a sham injection procedure carefully mimics a real injection procedure. Masking seems less successful when one eye is receiving a real injection and the other eye is receiving a sham injection or when an individual eye receives both real and sham injections.

Rationale for the diabetic retinopathy clinical research network treatment protocol for center-involved diabetic macular edema

OBJECTIVE

To describe the underlying principles used to develop a web-based algorithm that incorporated intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment for diabetic macular edema (DME) in a Diabetic Retinopathy Clinical Research Network (DRCR.net) randomized clinical trial.

DESIGN

Discussion of treatment protocol for DME.

PARTICIPANTS

Subjects with vision loss resulting from DME involving the center of the macula.

METHODS

The DRCR.net created an algorithm incorporating anti-VEGF injections in a comparative effectiveness randomized clinical trial evaluating intravitreal ranibizumab with prompt or deferred (≥24 weeks) focal/grid laser treatment in eyes with vision loss resulting from center-involved DME. Results confirmed that intravitreal ranibizumab with prompt or deferred laser provides superior visual acuity outcomes compared with prompt laser alone through at least 2 years. Duplication of this algorithm may not be practical for clinical practice. To share their opinion on how ophthalmologists might emulate the study protocol, participating DRCR.net investigators developed guidelines based on the algorithm's underlying rationale.

MAIN OUTCOME MEASURES

Clinical guidelines based on a DRCR.net protocol.

RESULTS

The treatment protocol required real-time feedback from a web-based data entry system for intravitreal injections, focal/grid laser treatment, and follow-up intervals. Guidance from this system indicated whether treatment was required or given at investigator discretion and when follow-up should be scheduled. Clinical treatment guidelines, based on the underlying clinical rationale of the DRCR.net protocol, include repeating treatment monthly as long as there is improvement in edema compared with the previous month or until the retina is no longer thickened. If thickening recurs or worsens after discontinuing treatment, treatment is resumed.

CONCLUSIONS

Duplication of the approach used in the DRCR.net randomized clinical trial to treat DME involving the center of the macula with intravitreal ranibizumab may not be practical in clinical practice, but likely can be emulated based on an understanding of the underlying rationale for the study protocol. Inherent differences between a web-based treatment algorithm and a clinical approach may lead to differences in outcomes that are impossible to predict. The closer the clinical approach is to the algorithm used in the study, the more likely the outcomes will be similar to those published.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Effect of duration and level of supplementation of diets of lactating dairy cows with selenized yeast on selenium concentrations in milk and blood after the withdrawal of supplementation

Cows' milk containing elevated concentrations of Se provides a rich nutritional source of this essential element for meeting daily nutritional requirements or providing health benefits in humans with low immune function or at risk of cancer. An experiment involving either 2 or 6 wk of dietary supplementation with Se yeast (with the yeast supplying about 30, 40, and 60 mg of Se/d for cows supplemented for 2 wk, and about 20, 30, 40, and 60 mg of Se/d for cows supplemented for 6 wk), and 21 wk of monitoring of Se status after the withdrawal of supplementation, was undertaken between September 2008 and April 2009 using 35 multiparous Holstein-Friesian cows. Using milk and blood Se concentrations as surrogates, the research examined the time taken for Se build-up in tissue due to supplementation of lactating dairy cows with Se yeast to dissipate back to normal levels. At the end of Se supplementation, a significant relationship was found between milk Se concentration and Se intake, whereby milk Se concentration had increased by 4.5 μg of Se/kg of milk for each mg of Se eaten per day, but no effect of duration of supplementation on this relationship was observed. At the same time, both Se intake and duration of supplementation affected blood Se concentration; it increased by 3.6 μg of Se/kg of blood for each mg of Se eaten per day, and was 86 μg of Se/kg higher after 6 wk compared with 2 wk of supplementation. After the withdrawal of Se supplementation, milk Se concentrations responded quickly to the change in the quantity of Se consumed, and again, duration of supplementation had no effect on the response, but any effect that Se intake had on milk Se had completely dissipated by 4 wk. In contrast to milk, blood Se concentrations continued to be affected by both amount and duration of Se supplementation for at least 4 mo after the withdrawal of supplementation, although by 5 mo the effects of the previous supplementation treatments had virtually disappeared. The slow decline in blood Se concentrations after the withdrawal of supplementation would most likely be due to the protracted clearance of Se from the various tissues that had accumulated Se during supplementation and the rate of erythrocyte turnover. When undertaking an on-farm Se enhancement program to generate milk for the manufacture of Se-enriched milk products, post-supplementation milk Se concentrations are unlikely to create any problems at the milk factory beyond 4 wk, but the high residual blood/tissue Se concentrations that take considerably more time to dissipate may provide the potential for possible unintended consequences at the food chain/farm environment level.

Expanded 2-year follow-up of ranibizumab plus prompt or deferred laser or triamcinolone plus prompt laser for diabetic macular edema

OBJECTIVE

To report expanded 2-year follow-up of a previously reported randomized trial evaluating intravitreal 0.5 mg ranibizumab or 4 mg triamcinolone combined with focal/grid laser compared with focal/grid laser alone for treatment of diabetic macular edema (DME).

DESIGN

Multicenter, randomized clinical trial.

PARTICIPANTS

A total of 854 study eyes of 691 participants with visual acuity of 20/32 to 20/320 (approximate Snellen equivalent) and DME involving the fovea.

METHODS

Continuation of procedures previously reported for the randomized trial.

MAIN OUTCOME MEASURES

Best-corrected visual acuity and safety at the 2-year visit.

RESULTS

At the 2-year visit, compared with the sham + prompt laser group, the mean change in the visual acuity letter score from baseline was 3.7 letters greater in the ranibizumab + prompt laser group (95% confidence interval adjusted for multiple comparisons [aCI], -0.4 to +7.7), 5.8 letters greater in the ranibizumab + deferred laser group (95% aCI, +1.9 to +9.8), and 1.5 letters worse in the triamcinolone + prompt laser group (95% aCI, -5.5 to +2.4). After the 1- to 2-year visit in the ranibizumab + prompt or deferred laser groups, the median numbers of injections were 2 and 3 (potential maximum of 13), respectively. At the 2-year visit, the percentages of eyes with central subfield thickness ≥250 μm were 59% in the sham + prompt laser group, 43% in the ranibizumab + prompt laser group, 42% in the ranibizumab + deferred laser group, and 52% in the triamcinolone + prompt laser group. No systemic events attributable to study treatment were apparent. Three eyes in 3 (0.8%) of 375 participants had injection-related endophthalmitis in the ranibizumab groups, whereas elevated intraocular pressure and cataract surgery were more frequent in the triamcinolone + prompt laser group.

CONCLUSIONS

The expanded 2-year results reported are similar to results published previously and reinforce the conclusions originally reported: Ranibizumab should be considered for patients with DME and characteristics similar to those of the cohort in this clinical trial, including vision impairment with DME involving the center of the macula.

Output of selenium in milk, urine, and feces is proportional to selenium intake in dairy cows fed a total mixed ration supplemented with selenium yeast

Fifteen rumen fistulated Holstein cows in late lactation and fed a total mixed ration offered ad libitum were supplemented with Se yeast to provide 0, 11, 20, 30, or 42 mg of supplemental Se/day to test the hypothesis that amounts of Se secreted in milk, excreted in urine and feces, and apparently retained in tissues would increase in direct proportion to Se intake. One-half of the yeast supplement was placed directly into the rumen through the fistula of each cow just before milking in the morning and again in the evening, and estimates of average daily excretion of Se were made using total collections of urine and feces from 25 to 31 d after treatments commenced. Amounts of Se secreted daily in milk and apparently retained in tissues increased linearly with average daily intake of Se. The amount of Se excreted in feces and total excretion of Se in urine plus feces increased curvilinearly with Se intake, such that proportionately less Se was excreted as the amount of Se fed increased. On average, total Se excretion accounted for 66%, Se secretion in milk accounted for 17%, and Se apparently retained in tissues accounted for 17% of total Se intake by cows. Thus, in herds fed large amounts of Se yeast, most of the Se will be excreted and retained on-farm. High concentrations of Se will be found where urine and feces accumulate (e.g., yards and effluent ponds), and effluent management practices must be tailored to avoid environmental issues.

Randomized trial evaluating ranibizumab plus prompt or deferred laser or triamcinolone plus prompt laser for diabetic macular edema

OBJECTIVE

Evaluate intravitreal 0.5 mg ranibizumab or 4 mg triamcinolone combined with focal/grid laser compared with focal/grid laser alone for treatment of diabetic macular edema (DME).

DESIGN

Multicenter, randomized clinical trial.

PARTICIPANTS

A total of 854 study eyes of 691 participants with visual acuity (approximate Snellen equivalent) of 20/32 to 20/320 and DME involving the fovea.

METHODS

Eyes were randomized to sham injection + prompt laser (n=293), 0.5 mg ranibizumab + prompt laser (n=187), 0.5 mg ranibizumab + deferred (> or =24 weeks) laser (n=188), or 4 mg triamcinolone + prompt laser (n=186). Retreatment followed an algorithm facilitated by a web-based, real-time data-entry system.

MAIN OUTCOME MEASURES

Best-corrected visual acuity and safety at 1 year.

RESULTS

The 1-year mean change (+/-standard deviation) in the visual acuity letter score from baseline was significantly greater in the ranibizumab + prompt laser group (+9+/-11, P<0.001) and ranibizumab + deferred laser group (+9+/-12, P<0.001) but not in the triamcinolone + prompt laser group (+4+/-13, P=0.31) compared with the sham + prompt laser group (+3+/-13). Reduction in mean central subfield thickness in the triamcinolone + prompt laser group was similar to both ranibizumab groups and greater than in the sham + prompt laser group. In the subset of pseudophakic eyes at baseline (n=273), visual acuity improvement in the triamcinolone + prompt laser group appeared comparable to that in the ranibizumab groups. No systemic events attributable to study treatment were apparent. Three eyes (0.8%) had injection-related endophthalmitis in the ranibizumab groups, whereas elevated intraocular pressure and cataract surgery were more frequent in the triamcinolone + prompt laser group. Two-year visual acuity outcomes were similar to 1-year outcomes.

CONCLUSIONS

Intravitreal ranibizumab with prompt or deferred laser is more effective through at least 1 year compared with prompt laser alone for the treatment of DME involving the central macula. Ranibizumab as applied in this study, although uncommonly associated with endophthalmitis, should be considered for patients with DME and characteristics similar to those in this clinical trial. In pseudophakic eyes, intravitreal triamcinolone + prompt laser seems more effective than laser alone but frequently increases the risk of intraocular pressure elevation.

Risk of endophthalmitis after intravitreal drug injection when topical antibiotics are not required: the diabetic retinopathy clinical research network laser-ranibizumab-triamcinolone clinical trials

OBJECTIVE

To report the incidence of endophthalmitis after intravitreal drug injection by means of a standardized procedure that does not require topical antibiotics, sterile gloves, or a sterile drape.

METHODS

Intravitreal injections of preservative-free triamcinolone acetonide or ranibizumab were administered in 2 prospective randomized clinical trials performed by the Diabetic Retinopathy Clinical Research Network. The standardized procedure for these trials requires the use of a topical combination product of povidone-iodine, a sterile lid speculum, and topical anesthetic, but does not require the use of topical antibiotics before, on the day of, or after injection.

RESULTS

As of February 23, 2009, a total of 3226 intravitreal injections of ranibizumab and 612 injections of preservative-free triamcinolone had been administered. Topical antibiotics were given on the day of injection in 361 (9.4%) of the 3838 cases, for several days after injection in 813 cases (21.2%), on the day of injection and after injection in 1388 cases (36.2%), and neither on the day of injection nor after injection in 1276 cases (33.3%). Three cases of culture-positive endophthalmitis occurred after ranibizumab injections (0.09%), and no cases occurred after triamcinolone injections. In all 3 cases of endophthalmitis, topical antibiotics were given for several days after the injection but not before injection.

CONCLUSIONS

The results suggest that a low rate of endophthalmitis can be achieved by means of a protocol that includes use of topical povidone-iodine, a sterile lid speculum, and topical anesthetic, but does not require topical antibiotics, sterile gloves, or a sterile drape. Trial Registration clinicaltrials.gov Identifiers: NCT00444600 and NCT00445003.

Increasing amounts of crushed wheat fed with pasture hay reduced dietary fiber digestibility in lactating dairy cows

Sixteen cows in mid-lactation (milk yield of 23.8 +/- 2.3 kg/d) were individually fed diets consisting of chopped perennial ryegrass hay, offered at 3 kg of dry matter (DM)/100 kg of body weight (BW), fed either alone or supplemented with amounts of crushed wheat ranging from 0.4 to 1.6 kg of DM/100 kg of BW (increasing at nominal intervals of 0.4 kg of DM/100 kg of BW; 5 nominal treatments in total). Three cows were allocated to each treatment except the mid-range wheat treatment, which had 4 cows. Results were analyzed by regression because the intake of the wheat by cows within treatments varied. The hay was used to reflect the characteristics of summer pastures in southeastern Australia. Feed intake and fecal output were measured to determine digestion coefficients, feeds were incubated in nylon bags in the rumen, and rumen variables were monitored. Estimates of metabolizable energy (ME) of the hay from in vivo or in vitro digestibility were also compared. The digestibility of neutral detergent fiber (NDF) was depressed linearly as the amount of crushed wheat consumed increased to 36% of DM intake. The extent to which negative associative effects on NDF digestion were associated with the hay could not be determined, as it was not possible to distinguish between the NDF from hay and that from wheat. However, acid detergent fiber (ADF) digestion also declined, suggesting that most of the response lay with the hay because ADF was negligible in the wheat. Most data indicated that effects of proportion of wheat in the diet on the utilization of consumed nutrients were small. Despite substitution of wheat for hay reducing the forage intake of cows, there was a positive linear effect on marginal milk responses (1.3 kg of energy-corrected milk/kg of DM wheat). Mean rumen fluid pH declined as the proportion of wheat in the diet increased. The lowest pH for any individual cow during a 24-h period was 5.4, and the amount of time that rumen fluid pH was <6.0 ranged from 0 to 14 h depending on the amount of wheat consumed. It was concluded that these perturbations of the rumen environment were probably sufficient to result in negative associative effects. In addition, estimates of the ME content of the hay were higher when calculated from in vitro compared with in vivo digestibility, which has implications when estimating the amount of feed required for production.

Increasing Selenium Concentration in Milk: Effects of Amount of Selenium from Yeast and Cereal Grain Supplements

Two experiments were conducted to establish responses in milk Se concentrations in grazing dairy cows to different amounts of dietary Se yeast, and to determine the effects of the Se concentration of the basal diet. The hypothesis tested was that the response in milk, blood, and tissue Se concentrations to supplemental Se would not be affected by whether the Se was from the basal diet or from Se yeast. In addition, by conducting a similar experiment in either early (spring; experiment 1) or late (autumn; experiment 2) lactation, we hypothesized that different Se input-output relationships would result. Both 6-wk experiments involved 60 multiparous Holstein-Friesian cows, all of which had calved in spring. They were allocated to 1 of 10 dietary Se treatments that included 2 types of crushed triticale grain (low Se, approximately 165 microg of Se/kg of DM; or high Se, approximately 580 microg/kg of DM) fed at 4 kg of DM/d, and 1 kg of DM/d of pellets formulated to carry 5 quantities of Se yeast (0, 4, 8, 12, or 16 mg of Se). Daily total Se intakes ranged from <2 to >18 mg/cow in both experiments. Milk Se concentrations plateaued after 15 and 7 d of supplementation in experiments 1 and 2, respectively, and then remained at plateau concentrations. Average milk Se concentrations for the plateau period increased as the amount of Se yeast increased, and low- and high-Se grain treatments were different at all quantities of Se yeast, although there was a tendency for this difference to diminish at the greatest concentrations of yeast. There were significant positive, linear relationships between Se intake and the concentrations of Se in milk, which were not affected by the source of Se, and the relationships were similar for both experiments. Therefore, the output of Se in milk in experiment 1 was greater than that in experiment 2 because the milk yield of the cows in early lactation was greater. The estimated proportions of Se partitioned to destinations other than milk and feces increased with the amount of Se in the diet and were greater in experiment 2 than in experiment 1, a result that was supported by Se concentrations in whole blood and plasma and in semitendinosus muscle tissue. If high-Se products are to be produced for human nutrition, it is important to be able to develop feeding systems that produce milk with consistent and predictable Se concentrations so that products can consistently meet specifications. The results indicate that this objective is achievable.

A phase II randomized clinical trial of intravitreal bevacizumab for diabetic macular edema

OBJECTIVE

To provide data on the short-term effect of intravitreal bevacizumab for diabetic macular edema (DME).

DESIGN

Randomized phase II clinical trial.

PARTICIPANTS

One hundred twenty-one eyes of 121 subjects (109 eligible for analysis) with DME and Snellen acuity equivalent ranging from 20/32 to 20/320.

INTERVENTIONS

Random assignment to 1 of 5 groups: (A) focal photocoagulation at baseline (n = 19), (B) intravitreal injection of 1.25 mg of bevacizumab at baseline and 6 weeks (n = 22), (C) intravitreal injection of 2.5 mg of bevacizumab at baseline and 6 weeks (n = 24), (D) intravitreal injection of 1.25 mg of bevacizumab at baseline and sham injection at 6 weeks (n = 22), or (E) intravitreal injection of 1.25 mg of bevacizumab at baseline and 6 weeks with photocoagulation at 3 weeks (n = 22).

MAIN OUTCOME MEASURES

Central subfield thickness (CST) on optical coherence tomography and best-corrected visual acuity (VA) were measured at baseline and after 3, 6, 9, 12, 18, and 24 weeks.

RESULTS

At baseline, median CST was 411 mum and median Snellen VA equivalent was 20/50. Compared with group A, groups B and C had a greater reduction in CST at 3 weeks and about 1 line better median VA over 12 weeks. There were no meaningful differences between groups B and C in CST reduction or VA improvement. A CST reduction > 11% (reliability limit) was present at 3 weeks in 36 of 84 (43%) bevacizumab-treated eyes and 5 of 18 (28%) eyes treated with laser alone, and at 6 weeks in 31 of 84 (37%) and 9 of 18 (50%) eyes, respectively. Combining focal photocoagulation with bevacizumab resulted in no apparent short-term benefit or adverse outcomes. Endophthalmitis developed in 1 eye. The following events occurred during the first 24 weeks in subjects treated with bevacizumab without attributing cause to the drug: myocardial infarction (n = 2), congestive heart failure (n = 1), elevated blood pressure (n = 3), and worsened renal function (n = 3).

CONCLUSION

These results demonstrate that intravitreal bevacizumab can reduce DME in some eyes, but the study was not designed to determine whether treatment is beneficial. A phase III trial would be needed for that purpose.

Acute post-parturient haemoglobinuria in dairy cows and phosphorus status

During the conduct of an experiment designed to examine the nutritional management of dairy cows in late pregnancy, four cows out of 72 suffered from acute haemoglobinuria two to four weeks after calving. Thirty-six thin and 36 fat cows were individually fed one of three diets based on a total mixed ration with different energy or protein concentrations during the last 3 to 4 weeks before expected calving date. After calving, cows grazed pasture and were offered 6 kg dry matter of pelleted concentrates daily. The P concentrations of the feeds offered suggested that the cows' diets were marginally deficient in P relative to requirements. Plasma P concentrations were significantly (P < 0.05) lower in fat cows than in thin cows during the first 6 weeks of lactation (0.87 versus 1.12 mmol/L), but precalving diet had no effect (P > 0.05). Concentrations of plasma inorganic P of the four fat cows that developed acute haemoglobinuria were less than 0.3 mmol/L. However, plasma P concentrations in another 12 cows, none of which displayed overt symptoms, declined to similar levels. It appeared that inadequate dietary P may have predisposed cows to acute haemoglobinuria, but the precipitating cause was not readily obvious.

Relationships Among International Body Condition Scoring Systems

Scoring body condition and assessing changes in the body condition of dairy cattle have become strategic tools in both farm management and research. Consequently, body condition score (BCS) is being researched extensively throughout the world. However, international sharing, comparing, and use of data generated are limited because different BCS systems exist. In the United States and Ireland a 5-point BCS system is used for dairy cows, whereas Australia and New Zealand use 8- and 10-point scales, respectively. The New Zealand 10-point scale was compared with the scoring systems in the United States, Ireland, and Australia by trained assessors. Cows were assessed visually in the United States and Australia, and in Ireland, cows were assessed by palpating key areas of the cow's body (n = 154, 110, and 120, respectively). Data were analyzed by regression. Significant positive linear relationships were found between the New Zealand 10-point scale and the other scoring systems: US 5-point scale, r(2) = 0.54; Irish 5-point scale, r(2) = 0.72; and Australian 8-point scale, r(2) = 0.61. Those relationships must be interpreted cautiously because respective BCS within a given country were by just one experienced evaluator in each country in comparison to a separate evaluator scoring all cows in all counties using the New Zealand 10-point scale. Also, few very thin or very fat cows limit evaluation across extremes of BCS. However, differences between systems were not accurately predicted by simple mathematical calculations. The relationship may be closer for New Zealand and Ireland (r(2) = 0.72) because both of those scoring systems include palpation of individual body parts, whereas visual evaluation is done in Australia and the United States. The current study is the first to examine relationships among differing BCS systems. These results may be useful for comparing/extrapolating research findings from different countries.

Substitution and production responses when lactating dairy cows graze a white clover pasture supplemented with maize silage

Friesian cows (16) in late lactation grazed pure white clover (Trifolium repens cv. Haifa) swards for 32 days in autumn and were supplemented with maize (Zea mays) silage. Four groups of 4 cows were offered either 19 or 39 kg dry matter (DM)/cow.day of white clover with either 0 or 4.4 kg DM/cow.day of maize silage. All cows were individually fed maize silage and grazed the pasture as individual groups according to treatment. When maize silage was fed, total intake increased, this occurring to a greater degree at the low pasture allowance. The level of substitution of silage for pasture was 0.14 and 0.40 kg DM reduction in pasture intake per kg DM of maize silage eaten at the low and high allowances, respectively. At the low pasture allowance, milk yields were 10.1 and 13.7 kg/cow. day when 0 and 4.4 kg DM/cow.day of maize silage were fed, respectively, and were 15.5 and 15.9 kg/cow.day at the high pasture allowance. Liveweight and body condition increased as plane of nutrition increased but there were no effects of feeding on milk fat or protein contents. Feeding maize silage had little effect on any rumen or faecal variable although there was generally less ammonia nitrogen in rumen fluid when cows were supplemented with maize silage.

Maize silage as a supplement for pasture-fed dairy cows in early and late lactation

Eight experiments were conducted over 2 years with 92 lactating dairy cows individually fed various combinations of irrigated perennial pasture and maize silage in an indoor feeding facility. Responses to different amounts of maize silage and pasture in early and late lactation were measured. Daily pasture intake ranged from 6.2 to 12.4 kg dry matter (DM)/cow, while maize silage intake ranged from 0 to 12.4 kg DM/cow. The marginal return to feeding maize silage at up to 5 kg DM/cow.day to cows in early lactation eating about 7 kg DM/day of pasture as their basal ration was 0.89 kg extra milk for each kg DM maize silage eaten. In late lactation, this was reduced to 0.63 kg milk/kg DM. Milk yield responses to maize silage at both stages of lactation were lower at higher levels of pasture feeding. Although milk fat content was maintained over a wide range of maize silage, feeding large quantities of maize silage in early lactation was detrimental to milk production. The likely explanation for poor animal performance at the high levels of maize silage was dietary protein insufficiency.

The productivity of lactating dairy cows grazing white clover and supplemented with maize silage

Ten grazing studies were undertaken in which lactating cows either grazed limited amounts of pure white clover (Trifolium repens cv. Haifa) alone, or were supplemented with 3.4-5.0 kg DM/cow day-1 of maize silage. Marginal returns to additional feeding were 0.58 and 1.03 kg of 4% fat-corrected milk/kg of total DM in spring/early summer (when cows were producing >20 kg milk/day) and autumn (when cows were producing <20 kg milk/day) respectively. While the responses from the lower producing cows were exceptionally good, the relativity between the two groups of cows was contrary to normal expectations; an increase in feeding should result in a greater response from the higher producing cows. The protein level in the clover diet was only slightly lower (23 v. 25%) in spring/summer than in autumn, yet this was associated with significantly (P < 0.05) lower mean rumen ammonia concentrations (114 v. 190 mg/L), indicating that rumen degradable protein may have limited the utilization of energy from maize silage in spring/summer. This is supported by higher faecal nitrogen concentrations recorded in spring/summer. Concentrations of condensed tannins in clover were also higher in spring/summer than in autumn (0.7 v. 0.2%). It is suggested that a significant proportion of the clover protein complexed with the condensed tannins occurring in the flowers present in the sward in spring/summer.

Nutritional evaluation of whole plant maize ensiled at three chop lengths and fed to lactating dairy cows

Whole crop maize (Zea mays) was chopped at 3 lengths before ensiling; the maize was harvested with a precision chop harvester with screen apertures of either 9 cm2 (fine chopped maize), 36 cm2 (medium chopped maize), or no screen at all (coarse chopped maize). The 3 silages were each fed as a supplement to pasture to lactating dairy cows in 2 experiments. Although some of the variables measured to assess silage quality suggested that the preservation process may have deteriorated as length of chop increased, length of chop of maize generally appeared to have little effect on silage quality or milk production. In experiment 1, cows ate about 7 kg DM of pasture and 8-9 kg DM of maize silage per day. Mean daily milk yields for the cows offered fine, medium and coarse chopped silage were 18.0, 17.7 and 18.2 kg/cow, respectively. In experiment 2, where daily intakes of each maize silage covered the range of 0-10.7 kg DM/cow, regression analysis could not detect any differences in milk responses between chop lengths. We concluded that aspects other than nutritional considerations should determine the length of chop that farmers aim for when making maize silage; these include ease of compaction in the bunker to ensure the production of good quality silage, and fuel consumption during harvesting.

Influence of defoliation on some aspects of regrowth and senescence of Persian clover herbage grown in pots

This experiment investigated the effects of defoliation management of Persian clover (Trifolium resupinatum) on herbage production, and in particular, regrowth and losses of production due to senescence. Three heights of defoliation of Persian clover (0, 5, 10 cm above soil level) were superimposed on 3 frequencies of defoliation (4, 6, 12 weeks between harvests until early October; 3, 4.5, 9 weeks subsequently) in a completely randomised pot experiment with 3 replicates. Defoliation management had a large effect on yield of harvested herbage, in agreement with earlier studies with Persian clover in mixed swards or as a monoculture in the field. The amount of herbage that grew below defoliation height and subsequently died was 0-21% of the total herbage grown. The amount of dead and dying matter in herbage above and below defoliation height increased as both defoliation height and interval increased. This represented up to 61% of the total herbage grown. Aspects of regrowth (leaf area, petiole number, petiole extension rate, yield of herbage during growth, biomass of root relative to shoot) were measured. Except at very long defoliation intervals, vegetative growth of Persian clover herbage was positively associated with all of the above variables. The pattern of change with time in the rate of green herbage accumulation following defoliation reflected the balance between changes in the growth of new plant tissue and the loss of mature tissue to senescence and decomposition.

Persian clover and maize silage. III. Rumen fermentation and balance of nutrients when clover and silage are fed to lactating dairy cows

Six rumen fistulated dairy cows, at various stages of lactation, were housed in metabolism stalls on a total of nine occasions in three experiments in which various combinations of Persian clover (Trifolium resupinatum) and maize (Zea mays) silage were offered. These experiments considered some aspects of digestion of Persian clover and Persian clover/maize silage diets in order to understand the good milk yield responses attributed to maize silage measured in previous research. Rumen ammonia concentrations and nylon bag degradation rates suggested that the cows made better use of one or both feeds when Persian clover and maize silage were offered together than they did when Persian clover was offered alone. While Persian clover and maize silage appeared to be a substantially inferior diet in terms of apparent in vivo digestibility coefficients and availability of nutrients when compared with Persian clover offered alone, milk yields were unaffected. In addition, no matter how much maize silage was offered, milk fat content remained constant. These results were attributed to an improved balance of absorbed nutrients.

Persian clover and maize silage. I. Silage as a supplement for lactating dairy cows offered herbage of different quality

A penfeeding experiment, involving 29 lactating dairy cows, was undertaken to assess the use of Persian clover (Trifolium resupinaturn) herbage instead of perennial ryegrass (Lolium perenne)-dominant herbage as the basal ration in diets in which maize silage (0 to 10.6 kg DM/cow day-1) was used as a supplement. This was supported by a second experiment in which 16 cows grazed limited amounts of Persian clover pasture (herbage allowance of 16.5 kg DM/cow day-1) and were supplemented with various amounts of maize silage (0 to 8.3 kg DM/cow daym-1). In the pen experiment, feeding maize silage to cows grossly underfed with perennial ryegrass pasture resulted in a marginal response to additional feeding of 0.9 kg milk for each of the first 5 kg DM of supplement eaten. This level of supplementary feeding constituted about 40% of the diet. Thereafter, maize silage resulted in virtually no additional milk and the best fed cows only produced about 20 kg of milk. A much greater response in milk yield (1.4 kg milk/kg DM of additional maize silage eaten) was obtained when Persian clover was substituted as the basal ration. There were no differences in milk composition or changes in body condition between cows offered the different basal herbages. Milk fat content averaged 3.9% across all cows, while milk protein content and change in body condition increased by 0.03% and 0.13 units for each additional kg DM of maize silage eaten each day. In the grazing experiment, when a small amount of maize silage was fed to the cows, the marginal return was 1.2 kg milk for each additional kg DM of maize silage eaten. This is only slightly lower than that reported for the indoor feeding study. A major reason for the good response was the negligible substitution of maize silage for Persian clover that occurred with the first increment of supplement in the diet. With higher levels of maize silage feeding, no extra milk was produced. It was the increase in the level of substitution at the higher levels of maize silage that eliminated the possibility of additional responses in milk production.

The productivity of lactating dairy cows fed irrigated Persian clover (Trifolium resupinatum)

A number of experiments were undertaken to establish the productivity of lactating dairy cows when offered green, vegetative Persian clover (Trifolium resupinatum) herbage and to study its utilization by these cows. The research included indoor feeding and grazing experiments and intensive metabolism studies. Levels of daily intake varied from 1.3 to 4.5 kg DM/100 kg liveweight and in early-to-mid lactation, milk yields as high as 30 kg/day were sustained. In early-to-mid lactation, marginal returns to additional feeding were 1.24 kg milk, 0.046 kg fat and 0.034 kg protein for each additional kg DM of Persian clover eaten by cows weighing 500 kg. In late lactation, marginal returns were 1.10, 0.050 and 0.035 kg/kg DM for milk, fat and protein, respectively. In a grazing experiment, utilization of herbage on offer was very high, ranging from 58-88% as grazing intensity increased. Consideration of the products of digestion suggested that fermentation of Persian clover herbage in the rumen resulted in a balance of metabolites that is unlikely to be detrimental to animal production. However, there were two aspects of rumen fermentation that could influence the potential utilization of the herbage. First, for much of the year, levels of ammonia in rumen fluid (up to 500 mg/L) were much higher than microbial requirements. Second, rumen fluid pH often dropped to about 5.5, a level which may inhibit cellulolysis. The implications of manipulating these aspects of rumen fermentation are discussed. It was concluded that, while few problems exist with the use of vegetative Persian clover for lactating dairy cows, this herbage may be used more efficiently if fed in conjunction with supplements that provide a better balance of nutrients for fermentation in the reticulorumen.

The nutritive value of Persian clover (Trifolium resupinatum) herbage grown under irrigation in northern Victoria

A series of experiments is described which considered the nutritive value of Persian clover (Trifolium resupinatum) (cv. Maral) herbage grown under irrigation in northern Victoria. Digestion studies were undertaken with sheep and dairy cows, and the degradation of herbage samples in nylon bags was evaluated. Digestion coefficients were estimated, leaf and stem characteristics were measured, mineral and amino acid profiles were obtained, and protein degradabilities were assessed throughout the period of growth of Persian clover. Freshly harvested Persian clover herbage utilized before flowering appears to be an excellent feedstuff for ruminants, and its chemical composition remains relatively constant until late spring. In vivo OM digestibilities were in the range, 75-85%, although this depended on feeding level and time of the year. When vegetative, nitrogen content ranged from 3.0 to 4.6%, and neutral and acid detergent fibre levels were 24-34 and 21-27%, respectively. Acid detergent lignin concentrations were between 2.1 and 4.5% of dry matter. Dry matter contents of the herbage were often very low; this could influence intake and digestion. The chemical composition of leaves and petioles/stems were very different. The digestibility of the leaf fraction was often much lower than that of the petiole/stem fraction, but its nitrogen content was higher. Reasons for this, and their implications, are discussed. Protein degradability in the rumen was lower than expected (<70%); this was attributed to very fast rates of flow of digesta out of the rumen. Herbage minerals generally appeared to be adequate. Implications of the degree of degradation of individual amino acids and minerals in the rumen are discussed. The use of chemical characteristics to predict the digestibility of Persian clover herbage is considered and discussed.

Influence of method of conservation of lucerne on factors associated with voluntary intake in sheep

This experiment measured the voluntary intake and rate of eating of sheep fed lucerne (Medicago sativa) that had been conserved as sun-dried material or as silage at 3 different DM contents (29.2, 33.1, and 51.2%). Changes in rumen osmolality and palatability due to diet were measured. Palatability was assessed by introducing feed directly into the rumen and measuring the subsequent oral intake. Eight sheep with rumen fistulae were used in two 4 x 4 latin squares, which allowed for adjustment for carryover effects. There was no significant (P<0.05) difference between voluntary intakes of lucerne conserved as sundried material and as silages of various DM contents (mean intake 1189 g DM/day). The lack of difference in intake was attributed to the high quality of fermentation of the silages. Rate of eating was also generally similar for all diets. Evidence from measurements of palatability and rumen osmolality support these observations. Palatability appeared not to influence the voluntary intake of any of the diets, because the sheep reduced their daily oral intake by an amount similar to that introduced into the rumen. Under normal feeding conditions, rumen osmolality was also similar for all feeds and was relatively consistent for the 9 h immediately after the start of feeding. While rumen osmolality per se may affect voluntary intake, the lack of response reported here for changes in osmolality due to diet support the lack of response reported for feed consumption.

The productivity of dairy cows fed irrigated subterranean clover herbage

A number of experiments were undertaken to establish the productivity of lactating dairy cows when offered green, immature subterranean clover (Trifolium subterraneum) herbage and to study its utilization by these cows. The research included indoor feeding and grazing experiments and intensive metabolism studies. Levels of daily intake varied from 8 to 22 kg DM/cow and in early lactation, milk yields as high as 28 kg/day were sustained. Marginal returns to extra feeding, up to 15 kg DM/day in early lactation, averaged 1.4 kg milk for each additional kg of DM eaten above 8 kg DM/day. In late lactation, the return to additional feeding was 1.0 kg milk/kg of extra DM consumed over a similar range. Beyond 15 kg DM/day, the return increasingly diminished. Consideration of products of digestion suggested that fermentation of subterranean clover herbage in the rumen resulted in a balance of metabolites that is unlikely to be detrimental to animal production. Although the milk production data for the cows in the early lactation experiments fitted well together, one grazing experiment (in winter) did produce an unusual result. In this experiment, the cows offered most pasture did not perform as well as those offered an intermediate amount. It was considered that this was due to a characteristic of subterranean clover whereby the leaves are considerably less digestible than the rest of the plant; this resulted in selection of a lower quality diet by the supposedly best fed cows. The implications of this are discussed. It was concluded that, while few problems exist with the use of vegetative subterranean clover for lactating dairy cows, lenient grazing is not the most productive strategy when leaves constitute a large proportion of the sward.

Maize silage for the pasture-fed dairy cow. 1. Effect of level of silage feeding, and responses to cottonseed meal while grazing perennial pastures in the spring

Dairy cows in early lactation were fed a maize-silage-based supplement at either 3 or 8 kg DM/cow.day, while grazing irrigated perennial pastures at 45 or 30 kg pasture DM/cow.day. The supplement consisted of maize silage, alone or with 16% DM replaced by cottonseed meal. A fifth group grazed at the higher pasture allocation with no supplements. Milk yield and composition, liveweight and body condition, and pasture intake were monitored over 10 weeks during late spring-early summer. Samples of pre- and post-grazed pasture, supplement, rumen fluid, and faeces were collected for chemical analyses. Supplemention increased total feed intake and milk yield of grazing cows, except at the higher level of silage without cottonseed meal. From data on nitrogen content of the grazed pasture and the supplement, together with rumen ammonia concentrations, it was concluded that low dietary protein levels limited milk yield in cows supplemented with 8 kg maize silage DM/day without the additional cottonseed meal. Liveweight and body condition score increases were greater in supplemented animals, while their rumen volatile fatty acid profiles suggested greater partitioning of nutrients towards lipogenesis in body tissue. Pasture was substituted at the rate of 0.67 kg DM for every kg maize silage DM consumed.

Effect of ensilation of lucerne on voluntary intake, digestibility, and eating and rumination behaviour in sheep

Twelve wether sheep were used in a 2 x 2 factorial experiment in which voluntary intake, diet digestibility, and eating and ruminating behaviour were compared when sheep were offered lucerne (Medicago sativa) as either wilted silage or hay. Chemical characteristics suggested that the lucerne silage was well fermented, and chemical compositions of the silage and hay were similar. Voluntary intakes were not significantly (P<0.05) different and were 1201 and 1220 g/day for silage and hay, respectively. Digestibilities of dry matter and organic matter were similar for both feeds, as were chewing behaviour and rumen physical function. Apparent crude protein digestibility was significantly (P<0.05) higher for silage than for hay (73.8 v. 70.3%). It was concluded that well-preserved lucerne silage has at least as high a feeding value as well-made lucerne hay.

Acceptability of high fat grain mixtures offered to grazing dairy cows

Levels of acceptance of mixtures of rolled oats and predominantly saturated, molten or free-flowing fatty acids were assessed with lactating dairy cows. Twenty cows grazed pasture and were offered rolled oats comprising 0, 2, 4, 8, 15, 25 or 40% (w/w) fatty acids. One kg/cow was offered twice daily to cows following milking. The acceptability of grain-fat mixtures was influenced by level of fatty acids. The fatty acid concentrations above which less than 95% of the supplement was consumed by animals ranged from 22 to 31%. Time spent eating the supplement was reduced by 2.4 s for every percentage unit increase in fatty acid concentration, while high air temperature increased (P<0.05) eating time.

Influence of high energy supplements containing fatty acids on the productivity of pasture-fed dairy cows

Three groups of 8 cows in their second month of lactation grazed irrigated perennial pasture alone, or grazed and were supplemented with either 3.3 kg/day of a high energy supplement or 3.8 kg of a high energy supplement containing additional long-chain fatty acids. Yields of milk and milk products were generally highest for those cows fed the supplement containing fat. Yield of milk fat was 13% higher in fat supplemented cows than those in the other supplemented treatment because these cows overcame the negative effect of starch supplements on milk fat test. Inclusion of long-chain fatty acids in the diet caused only minor changes in the fatty acid composition of the milk fat and in the various rumen parameters. The immediate marginal increases in daily yields of milk and milk fat per kg of long-chain fatty acids consumed by cows were 1.8 and 0.33 kg/cow. After comparison with data from other experiments, we concluded that the type of basal diet is not an important factor influencing the response of dairy cows to dietary long-chain fatty acids

The effect of a blend of dietary unesterified and saturated long-chain fatty acids on the performance of dairy cows in mid-lactation

This experiment studied the effects of feeding a supplement of a blend of unesterified and saturated long-chain fatty acids on the productivity of dairy cows in mid-lactation. Twenty-three cows in their fourth month of lactation were individually fed ad libitum, a mixed balanced ration based on maize silage, lucerne hay and rolled grain. Varying quantities, up to 1020 g cow-1 day-1 of the fatty acid supplement, were mixed into the ration. Yields of milk and milk products were linearly related to total long-chain fatty acid intake. Milk fat content increased linearly while milk protein content averaged 3.59 (s.d. � 0.15)%. The marginal returns from feeding 1 kg of the supplement were 3.3 kg milk, 0.33 kg fat and 0.07 kg protein. The proportions of C 10:0, C12:0 and C 14:0 fatty acids in milk were decreased, while those of C 18:0 and C18:1 were increased as the result of feeding long-chain fatty acids. The concentration of lipid in plasma was increased, but acetate and D-(3)-hydroxybutyrate levels in blood remained unchanged with increased levels of dietary long-chain fatty acid. Efficiency of milk production was increased by 11% from feeding 1 kg of the supplement. In vivo digestibilities of dry matter, neutral and acid detergent fibres, and dietary long-chain fatty acids were unaffected by supplement.

Effects of pasture and supplement quality on the responses of lactating dairy cows to high energy supplements

An experiment was conducted in which 30 stall-fed dairy cows were fed a basal ration of either good or poor quality pasture (approx. 7 kg DM) and supplemented with varying amounts of either crushed wheat or a pelleted. high energy supplement (0, 4 kg/clay or ad libitum). The cows were in their third month of lactation and were fed their allotted rations for 5 weeks. Where no supplements were fed, the approximate 9% difference in digestibility between pasture types resulted in differences in daily production of 2.4 kg milk/cow, 0.07 kg milk fat/cow and 0.06 kg milk protein/cow, and a difference of 0.4 units of body condition over a 5-week period. Where supplements were fed, responses depended on the interaction between a supplement and basal ration. With good quality pasture as the basal ration, the type of supplement was not important; marginal returns of milk products to extra feeding were similar for both supplements, for example, 1.0 kg milk/cow.day was produced for each additional kg of concentrate consumed. There was a reduction in milk fat production when more than about 5-6 kg DM of supplement was fed. This was due to a depression in the fat content of the milk which was associated with low dietary fibre (<250 g/kg of dietary neutral detergent fibre). However. when pellets were fed to cows offered poor quality pasture. a reduction in milk fat yield did not occur. When wheat supplemented poor quality pasture, on the other hand, deficiencies other than fibre were implicated. While fibre was the most important limitation to productivity when good quality pasture was supplemented with concentrates, protein was the most likely nutrient to limit productivity first when poor quality pasture formed the basal ration. The potential exists for major imbalances of nutrients to occur unless the composition of dietary components is known.

Effect of pasture feeding levels on the responses of lactating dairy cows to high energy supplements

Stall-fed dairy cows were fed amounts of pasture ranging from 6.7 to 11.8 kg DM/cow.day and supplemented with either 0, 2.2 or 4.5 kg DM/cow.day of pelleted concentrates. Twenty-eight cows in their third month of lactation and 29 cows in their eighth month of lactation were fed in this manner for about 5 weeks. Stage of lactation had a major influence on responses obtained from feeding a high energy supplement to pasture-fed cows. In early lactation, for cows fed 6.8 kg DM, marginal responses from feeding an additional kg DM of concentrates were 1.85, 0.053 and 0.059 kg milk, milk fat and milk protein, respectively; if they were fed 11.7 kg DM of pasture, marginal responses from concentrates were more than halved (0.58 kg milk, 0.019 kg milk fat and 0.027 kg milk protein per kg DM). The latter response to concentrates, where high levels of pasture were fed to cows in early lactation, were less than those obtained in late lactation at any level of pasture feeding.

Feeding high energy supplements to pasture-fed dairy cows. Effects of stage of lactation and level of supplement

Five experiments were done in which stall-fed dairy cows were provided with a basal ration of pasture (6-7 kg DM) which was supplemented with varying amounts of a pelleted, high energy supplement (0-10 kg DM). Forty-seven cows at various stages of lactation were fed in this manner for up to 5 weeks. Responses to feeding the supplement depended on the stage of lactation at which the supplement was fed, and the amount of the supplement consumed. Marginal responses in milk production fell from 1.6 to 0.7 kg milk per kg supplement as lactation progressed, and as the level of feeding increased. Although responses in milk fat yield also decreased as lactation advanced, there was also a reduction in milk fat production when more than about 6 kg DM of supplement were fed. This was due to a severe depression in the fat content of the milk, which was found to be associated with intakes of diets with less than 250 g kg DM-1 neutral detergent fibre; diets with less than this level of fibre resulted in ratios of lipogenic to glucogenic volatile fatty acids in the rumen below 4:1. This occurred when the supplement constituted 0.4-0.5 of the diet on a dry matter basis. In addition, rumen ammonia levels were low when large amounts of supplement were fed. With all rumen characteristics, stage of lactation had no influence on values.

Factors affecting the productivity of irrigated annual pastures. 1. Time of first irrigation in late summer-early autumn

The influence of time of first irrigation (mid-February, early March, or late March) on the productivity of an annual pasture was studied for 3 years in northern Victoria. Beginning the irrigation of annual pastures in late summer instead of at the normal time of late March- April provided additional herbage in autumn and winter and did not adversely affect herbage production in late winter-early spring; up to 2.3 t/ha DM of additional herbage was obtained by mid June and 4.3 t/ha DM over the whole season. Earlier irrigation also increased the subterranean clover content of the pasture, resulting in herbage that was lower in digestibility and higher in nitrogen content than that in the other treatments. The benefit of early irrigation in increasing clover content may be offset by invasion by weeds. In this experiment, a potential weed problem in the earliest irrigation treatment appeared at the beginning of year 3.

Effect of pasture allowance and level of concentrate feeding on the productivity of dairy cows in late lactation

This experiment examined the effects of level of concentrate feeding and pasture allowance on the productivity of dairy cows in late lactation. Thirty-two cows in their 8th month of lactation were allocated to eight treatments; these were combinations of two pasture allowances (about 15 and 26 kg DM/cow.day) and four levels of concentrates (0,2,4 kg/cow.day and ad libitum). Milk and protein yields increased linearly with level of supplementation but the response of milk fat yield was curvilinear; peak fat yield occurred at 4 to 5 kg DM/cow.day of concentrates fed. The marginal returns from feeding 1 kg of concentrates were 0.57 kg milk, 0.030 kg fat and 0.022 kg protein from feeding up to 5 kg DM/ cow.day. The different pasture allowances significantly influenced only fat yield; the cows at the higher allowance produced 0.044 kg more fat than did the cows at the lower allowance.