Meta-analysis of the effects of ionophores supplementation on dairy cows performance and ruminal fermentation

• Published in: Livestock science 2021-12, Vol.254, p.104729, Article 104729
• Main Authors: de Moura, Daiane Caroline, Torres, Rodrigo de Nazaré Santos, da Silva, Henrique Melo, Donadia, Andrea Beltrani, Menegazzo, Leticia, Xavier, Mari Lúcia Marques, Alessi, Karine Cláudia, Soares, Suziane Rodrigues, Ghedini, Caren Paludo, Oliveira, Andre Soares de
• Format: Article
• Language: English
• Subjects: Additives; Lasalocid; Milk production; Monensin
• ISSN: 1871-1413; 1878-0490
• DOI: 10.1016/j.livsci.2021.104729

•We evaluated the effects of ionophores (IOP) supplementation at different doses to lactating dairy cows on their performance and ruminal fermentation through meta-analysis.•IOP supplementation 〈 15 mg/kg DM diet did not affect milk yield. Milk production increased when cows received IOP doses ranging from 15–25 mg/kg DM, it but reduced with 〉 25 mg/kg DM.•IOP supplementation did not affect rumen NH3N and acetate concentrations. Enhanced rumen concentration of propionate and reduced rumen concentration of butyrate were observed in cows receiving IOP.•Positives effects on performance were observed only with monensin and with cows ≤ 150 days in milk. IOP supplementation increased dairy performance regardless of the feeding system.•The effects of IOP supplementation on lactating dairy cows performance are mainly dose-dependent. A meta-analysis of 52 peer-reviewed papers was conducted to investigate the effects of ionophores (IOP) supplementation on the performance and ruminal fermentation of lactating dairy cows. We used random-effects models to examine the raw mean difference (RMD) between the IOP group (diets with IOP) and the control group (diets with no additives), weighed by inverse of the variance. We also evaluated the effects of the covariates IPO supplementation level dose groups (< 15; 15–20; 21–25; and > 25 mg/kg dry matter (DM) diet), IOP type (monensin or lasalocid), feeding system (total mixed ration or pasture) and days in milk (DIM) on RMD, by meta-regression and subgroup analysis. Overall, IOP supplementation (21.3 ± 8.3 mg/kg DM) reduced DM intake (DMI; RMD = - 0.39 ± 0.22 kg/d; P < 0.01; n = 82), but it increased milk yield (RMD = 0.43 ± 0.28 kg/d; P < 0.01; n = 87), and thereby increased feed efficiency. However, IOP supplementation reduced milk protein (RMD = -0.03 ± 0.02 g/100 g; P < 0.01; n = 79) and milk fat (RMD = -0.08 ± 0.05 g/100 g; P < 0.01; n = 70) contents. Overall, IOP supplementation had no effect on rumen pH (P = 0.29), NH3N (P = 0.63) and acetate concentrations (P = 0.08); however it enhanced the rumen concentration of propionate (P < 0.01) and reduced the rumen concentration of butyrate (P < 0.01). Most of the response variables analyzed herein had low and/or moderate heterogeneity (I2 < 25 and 26–50%, respectively). The ionophore dose was the major covariable impacting the IOP supplementation response (RMD) on animal performance. Ionophores supplementation at doses < 15 mg/kg DM had no effect on milk yield (P = 0.25). Howe