Changing the grazing session from morning to afternoon or including tannins in the diet was effective in decreasing the urinary nitrogen of dairy cows fed a total mixed ration and herbage

Our aim was to evaluate whether increasing soluble carbohydrates in the herbage by changing the time of the grazing session or including Acacia mearnsii tannin in the diet would affect intake, digestion, N partitioning, and productive performance of dairy cows fed a diet combining ryegrass herbage with partial total mixed ration (PMR). We hypothesized that both strategies could reduce the concentration of NH3-N in the rumen, reducing urinary N excretion. Nine Holstein cows were used in a triplicate 3 × 3 Latin square experiment with 3 experimental periods of 22 d. The cows were fed a fixed amount of PMR [60% of the predicted individual dry matter intake (DMI)], and an unrestricted amount of herbage in 1 grazing session of 5 h/d. The treatments were (1) morning grazing session and afternoon PMR meal (AM); (2) morning PMR meal and afternoon grazing session (PM); and (3) morning grazing session and afternoon PMR meal supplemented with 15.0 g of tannins/kg of PMR dry matter (TAN). Milk production was not affected by treatments. Although the protein concentration was lower for TAN than for PM, no differences were detected for the yield of any component between treatments. The concentration of individual or grouped fatty acids in milk fat was not affected by treatments, except for 16:1 cis-9 and Δ9-desaturase ratios 14:1/14:0 and 16:1/16:0, which were lower for TAN. Treatments did not affect total DMI, but PM tended to increase herbage DMI and reduce dry matter and crude protein digestibilities. Treatments did not affect cow eating and ruminating behavior except for the proportion of time spent eating PMR, which was higher for PM and TAN. Although no relevant effects of treatments on ruminal fermentation, purine derivatives excretion in urine, or N excretion in milk were detected, both PM and TAN decreased the total N excreted in urine by an average of 8% compared with AM. In conclusion, changing the grazing session from the morning to the afternoon and including tannins in the diet were effective in decreasing the excretion of urinary N but did not change the productive performance of dairy cows fed PMR and ryegrass herbage.Fil: Pozo, Claudio. Universidade Federal de Santa Maria; BrasilFil: Kozloski, Gilberto V.. Universidade Federal de Santa Maria; BrasilFil: Cuffia, Maira. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Repetto, José L.. Universidad de la República; UruguayFil: Cajarville, Cecilia. Universidad de la República; Urugua

Productive response to two concentrate allocation strategies in dairy cows grazing with restricted pasture allowance

The objective of this study was to compare the effects of two concentrate allotment strategies on the performance of dairy cows grazing on restricted pasture and supplemented with conserved forage. Dairy cows fed equal amounts of concentrate (fixed daily rate: 5.5 kg DM/cow) were compared to cows supplemented with concentrate according to their lactation stage as follows: 10.0, 5.0, and 1.5 kg DM/cow daily during early, mid, and late lactation, respectively (average daily dose: 5.5 kg DM/cow). There was a supplementation strategy × lactation stage interaction (P < 0.05) for energy-corrected milk (ECM). For early lactation cows, supplementation at a variable rate increased ECM yield by 14.61% (P < 0.05). There was a supplementation strategy × lactation stage interaction (P < 0.05) for body weight change. At late lactation stage, cows supplemented at a fixed rate gained weight (+ 0.16 kg/day), whereas those supplemented at a variable rate lost weight (– 0.08 kg/day; P < 0.05). No significant effect was found for body condition score. The prioritization of milk production rather than the attenuation of body reserve mobilization suggests that concentrate allowance based on lactation stage may be unsuitable for minimizing the negative energy balance in early lactation cows.EEA PergaminoFil: Bretschneider, Gustavo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Agencia de Extensión Rural Necochea; ArgentinaFil: Salado, Eloy Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Cuatrin, Alejandra. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Mattera, Juan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Forrajeras; ArgentinaFil: Pece, Mariela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Arias, Dario. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Cuffia, Maira. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dieguez, Virginia. Actividad Privada; Argentin

A simplified feeding system did not affect milk production compared with a total mixed ration system in dairy cows

The objective of our study was to compare animal performance of a simplified feeding system, named easy feeding (EF), with animal performance of a total mixed ration (TMR) feeding system, using high yielding dairy cows in early lactation. Two treatments, TMR (n = 16) and EF (n = 16), were evaluated in a completely randomised design. Holstein cows (617 ± 85.1 kg of body weight and 52 ± 16 days in milk) were used. The TMR treatment consisted of a mix of concentrates, corn silage and alfalfa hay, mixed and offered twice a day, while EF treatment involved the same diet components offered separately, with concentrate offered individually in the milking parlour, alfalfa hay offered as bales and corn silage offered straight from the silo bag, with no intervention of machinery in the feeding process. The feeding system had no effect on milk production, fat and protein yield, total net energy intake, total dry matter intake, body weight, body condition score plasma metabolites and eating and ruminating time. Cows in EF system had higher non-fibrous carbohydrates intake, lower intakes of crude protein and neutral detergent fibre and longer drinking time than cows in TMR system. Cows in EF selected a diet according to their preferences, which may have allowed them to achieved similar milk yield to TMR cows, despite the advantages of mixed diets in TMR treatment. Thus, the EF system is an attractive alternative to traditional TMR system, provided that costs of feeding operations are effectively reduced.Highlights A new simplified feeding system was compared to TMR system Milk production was similar in both feeding systems Simplified feeding system is an attractive alternative to traditional TMR systems, provided that costs of feeding operations are effectively reduced in E