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Objective Our objective was to evaluate the effects of providing shade and shade combined with evaporative cooling on production, cow activity, metabolism, and hepatic gene expression of late-lactation Holstein dairy cows under moderate heat-stress conditions. Materials and Methods Forty-eight multiparous Holstein cows were used in a completely randomized block-design trial and randomly assigned to 1 of 3 treatments: control (CTL), without access to shade; access to artificial shade (SH); and shade combined with evaporative cooling (SHplus). Results were analyzed using a mixed procedure with repeated measures. Results and Discussion No differences were observed in DMI. Milk yield was not different among treatments, but lactose concentration was greater in SHplus. Treatments CTL and SH had greater BW losses than SHplus. Control cows spent less time grazing. The CTL and SH had higher p.m. rectal temperatures than SHplus, whereas CTL had the highest p.m. respiration rate. Control cows had greater serum insulin levels. Control and SH had greater BHB and urea concentrations and lower glucose concentration compared with SHplus. The hepatic expression of PCK1, PDK4, and HP genes was downregulated in SH and SHplus relative to control. Hepatic expression of NFKB1 was downregulated, whereas SOCS2 was upregulated, for SHplus compared with CTL. Implications and Applications Despite the absence of treatment effects on productive variables, changes in blood profiles and hepatic expression of target genes were observed among treatments. These results suggest that the provision of shade combined with evaporative cooling was effective in alleviating the negative effects of heat stress.

The aim of this study was to evaluate the effect of a sensory additive, incorporated into a starch-based concentrate, on milk production and composition and grazing behavior in pasture- fed dairy cows. Forty-five Holstein cows were used in 15 incomplete 3 × 2 Latin squares conducted concurrently with 3 treatments and 2 periods of 28 d At the beginning of the study, cows averaged 60 ± 17.1 d in milk, 2.2 ± 1.51 parity, 27.5 ± 4.52 kg/d of milk, and 504 kg ± 61.9 of BW (mean ± SD). Cows were assigned to the 15 squares by parity, milk yield, d in milk, and BW and within squares randomly assigned to 3 concentrate treatments that were 1 kg/d of a mineral concentrate (MC), 7 kg/d of a starch-based concentrate (CC), and 7 kg/d of CC supplemented with 30 g/d of a sensory additive (PEC; ProEfficient, Lucta SA, Barcelona, Spain). Cows grazed a perennial ryegrass pasture (Lolium perenne L.) offered at a daily allowance of 30 kg of DM per cow. Supplementation with the starch-based concentrate increased (P < 0.05) milk yield 4.4 kg/d compared with MC (24.3.vs. 28.7 kg/d), whereas cows supplemented with PEC produced more (P < 0.05) milk and energy-corrected milk than CC cows (0.6 and 1.6 kg/d, respectively). As a result, milk response to concentrate supplementation (kg milk/kg concentrate) was improved by PEC. Additionally, PEC increased (P < 0.05) milk protein percentage (3.74 vs. 3.43%) and yield (1.08 vs. 0.98 kg/d) compared with CC. Concentrate supplementation increased (P < 0.05) total DMI, but reduced (P < 0.05) total daily grazing time (GT) and biting rate (BR) in the evening. Compared with CC, PEC did not affect (P > 0.05) total and pasture DMI but increased (P < 0.05) GT during the first 2 h after the a.m. milking as well as BR and ruminating time during the diurnal hours. The plasma concentration of active ghrelin was similarly reduced (P < 0.05) by CC and PEC after 2 h of grazing. In summary, supplementation of a starch-based concentrate with a sensory additive improved milk and protein responses of dairy cows grazing a ryegrass pasture. Fil: Nannig, P.. Universidad Austral de Chile; Chile Fil: Pulido, R. G.. Universidad Austral de Chile; Chile Fil: Ruiz Albarrán, M.. Universidad Austral de Chile; Chile Fil: Bargo, Fernando. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Lucta; España Fil: Tedó, G.. Lucta; España Fil: Palladino, Rafael Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Unidad Ejecutora de Investigaciones en Producción Animal. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias. Unidad Ejecutora de Investigaciones en Producción Animal; Argentina Fil: Cussen, R.. BestFed; Chile Fil: Acuña, J.. BestFed; Chile Fil: Sheahan, A. J.. DairyNZ; Nueva Zelanda Fil: Roche, J. R.. Universidad Austral de Chile; Chile Fil: Ipharraguerre, I. R.. Lucta; España. University of Kiel; Alemania

There is increased public awareness of the effect of dietary fatty acid (FA) profile on human health. Therefore, when devising nutritional management strategies for dairy cows it is important to evaluate the effects of said strategies on the FA profile of the milk. This experiment investigates the effects of two early PP nutritional management strategies (NM); abrupt introduction to pasture (AP) or a total mixed ration for 21 d followed by a gradual introduction to pasture over 7 d (GP), with (Y) or without (C) live yeast (YS) on milk fatty acid (FA) profile. Forty multiparous dairy cows were assigned to one of four dietary treatments in a two (AP vs. GP) by two (Y vs. C) factorial, randomized block design. The experiment was conducted from d 1 to 70 PP. Pasture, TMR and concentrate samples were taken weekly to assess the chemical and FA composition. Milk yield was recorded daily and individual milk samples were collected weekly to determine milk FA composition. There was no interaction between NM strategy and YS supplementation on milk FA. Similarly, YS supplementation did not affect milk FA profile. However, GP had higher concentrations of C10 (P = 0.04), C12 (P = 0.01), C14 (P = 0.02) and medium chain FA (P = 0.02) vs. AP. Whereas AP had higher concentrations of the FA cis-9, C18:1 (P < 0.01), long chain FA (P = 0.1) and unsaturated FA (P = 0.01) and lower concentrations of saturated FA (P = 0.01) vs. GP. These results suggest that abruptly introducing the early lactation dairy cow to a pasture based diets positively alters the FA composition of the milk produced when compared to the milk from a dairy cow gradually introduced to pasture. Fil: Pierce, Karina Mary. University College Dublin; Irlanda Fil: Alibrahim, Radwan M.. Arasco; Arabia Saudita Fil: Palladino, Rafael Alejandro. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Animal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Whelan, Stephen Joseph. University College Dublin; Irlanda Fil: Mulligan, Finbar John. University College Dublin; Irlanda

The aim of this study was to assess the effect of three alfalfa pasture herbage allowances on milk yield and composition during autumn–winter grazing season on early autumn calving dairy cows. Eighteen multiparous Holstein dairy cows were assigned to one of three treatments in a 3 3 Latin square design: low herbage allowance (14 kg DM/cow; LHA), medium herbage allowance (27 kg DM/cow; MHA) and high herbage allowance (41 kg DM/cow; HHA). Dry matter disappearance was lower at LHA although remained similar between MHA and HHA (Po0.05). However, as herbage allowance (HA) increased, lower grazing efficiencies (as the proportion of material removed) were registered (Po0.05). Total dry matter intake (DMI; kg/d) was also lowest for LHA and similar between the other two treatments (Po0.05). Milk yield, 4%FCM, milk fat (g/kg) and casein (g/kg) tended to increase from LHA to HHA (Po0.10). Cows at LHA tended to loss weight whilst cows at MHA and HHA had a tendency to increase BW according the season progressed (Po0.10). In summary, managing cows at HHA will allow cows to a slightly increase in individual milk production and BW gain but in detriment of herbage utilization and potentially, milk production per hectare. Fil: Danelon, J. L.. Universidad de Buenos Aires. Facultad de Agronomia; Argentina Fil: Gaggiotti, M.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina Fil: Gallino, R.. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; Argentina Fil: Palladino, Rafael Alejandro. Universidad de Buenos Aires. Facultad de Agronomia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

The objective of this study was to investigate the effect of level of pre-grazing herbage mass (HM) and daily herbage allowance (DHA) on the fatty acid (FA) intake and composition of ruminal content of grazing dairy cows. Four rumen fistulated Holstein-Friesian dairy cows were allocated to either a high or low HM (1700 vs 2600 kg DM ha-1) and within herbage mass treatment further allocated to a high or low DHA (20 vs 16 kg of DM cow-1 day-1) in a 4 × 4 Latin square design. Total FA intake and linolenic acid (LNA) intake was higher for cows on high DHA (p

Relatively low ruminal pH values have been frequently registered in dairy cows grazing alfalfa, which can be involved in reducing feed digestion. An in vitro experiment was carried out to study the effect of ruminal pH (6.4, 6.1, 5.8 and 5.5) on the digestion of fresh alfalfa.Decreasing the pH, in vitro gas production (ivGP) decreased (P0.05). The lowest ivGP was registered at pH 5.5 and it was product of a higher lag time and a lower digestion rate. Dry matter disappearance (DMD) was not affected by pH at 48 h (P0.05). Neutral detergent disappearance (NDFD) at 48 h decreased below pH 6.1. The NDFD was reduced by 62% at pH 5.5 with respect to results at pH 6.4 and 6.1 (where the highest DMD and NDFD were observed).As expected, low rumen pH decreased alfalfa digestion. However, limits to ruminal digestion activity differed from those usually proposed for TMR diets. It is apparent that different relationships between rumen pH and NDFD exist when cows graze fresh alfalfa or grasses. Moreover, our results suggest the convenience to complement the data obtained through ivGP, DMD and NDFD. While ivGP and DMD seem to be more useful at early digestion times, NDFD may be a good predictor of final digestion.