Lourdes Llonch

The present study aimed to evaluate the potential hazardous effects of NO₃⁻ concentration in drinking water on health, feed intake, rumen fermentation and microbiota, and nitrogen excretion of Holstein heifers fed a high-concentrate diet for a sustainable water use. Twenty-four Holstein heifers were individually allocated and assigned to one of four treatments with increasing drinking water NO₃⁻ concentration: CTR, without NO₃⁻; LOW, with 44 mg NO₃⁻/L; MOD, with 110 mg NO₃⁻/L; and HIGH, with 220 mg NO₃⁻/L. The entire study lasted 168 days. Fortnightly water NO₃⁻ concentration and daily feed and water intake were recorded. Blood parameters, rumen pH, volatile fatty acids, NO₃⁻ and NO₂⁻ concentration, microbiota, and apparent total tract digestibility were determined at the beginning and at the end of the study. Most of the analyzed parameters were similar among treatments. Denitrifying bacteria population, estimated as nosZ gene copies, were greater in HIGH animals than in CTR animals at the end of the study. In conclusion, drinking water NO₃⁻ concentration up to 220 mg/L has no detrimental effect on health, feed intake, rumen fermentation, nor N excretion in dairy beef cattle for periods up to 168 days; moreover, denitrifying bacteria population increased, which are related with the neutralization of the greenhouse gas N₂O.

The aim of this study was to evaluate the effect of dietary alpha-amylase supplementation on growth performance and carcass quality in crossbred dairy beef bulls fed high-concentrate diets. Ninety-nine bulls (187 ± 2.6 kg of BW, and 146 ± 1.0 days of age) were grouped in 6 pens of 15 to 17 animals/pen and fed concentrate, straw, and water ad libitum. Pens were assigned to one of 2 treatments: 1) CTR (n = 51), no treatment; 2) RUM (n = 48), RumiStar600 CT concentrate inclusion (630 mg/kg DM, based on 600 kilo novo units (KNU) of alpha-amylase activity). After 168 days, using twelve 14-days periods to record daily concentrate intake per animal, daily water consumption per pen, and fortnightly BW per animal animals were transported to slaughterhouse within one month, the whole study lasted an average of 210 days. Also, on days 0, 42, 84 and 168 concentrate samples were collected for enzyme activity and nutrient content analyses. Carcass quality was recorded at the slaughterhouse. Data were analyzed using a mixed model. The BW was greater (P < 0.01; interaction treatment by time) in RUM than in CTR treatment from period 1 to period 12. Concentrate intake tended (P = 0.10) to be greater in RUM than in CTR treatment in periods 1, 9 and 10. Bulls from RUM treatment had a greater (P < 0.01) ADG and a better feed conversion ratio than CTR bulls in periods 8, 10 and 12. Water consumption was similar between treatments, and no health problems related to treatments were recorded. Treatment did not affect carcass conformation. Preslaughter BW (539 vs. 523 ± 6.4 kg, RUM vs. CTR, respectively; P = 0.01) and hot carcass weight (306 vs. 295 ± 4.1 kg, RUM vs. CTR, respectively; P < 0.01) were greater in RUM than in CTR bulls. Also, fatness grade tended (P = 0.08) to be greater in RUM than in CTR treatment (score 1: 8 vs. 25 %; score 2: 77 vs. 63 %; score 3: 15 vs. 12 %; RUM vs. CTR, respectively). In conclusion, dietary alpha-amylase supplementation (600 KNU of alpha-amylase activity/kg DM of concentrate) for at least 168 days improved growth performance and carcass quality in crossbred dairy beef bulls fed high-concentrate diets.

The aim of this study was to evaluate the effect of dietary alpha-amylase supplementation on growth performance and carcass quality in crossbred dairy beef bulls fed either pellet or mash high-concentrate diets. Two parallel studies were conducted in two barns. In the first barn, 138 bulls (170 ± 2.3 kg of BW, and 148 ± 0.7 days of age) were grouped in 8 pens of 16 to 19 animals/pen and fed pelleted concentrate (PELLET study); and in the second barn, 148 (180 ± 1.6 kg of BW, and 150 ± 0.7 days of age) were grouped in 8 pens of 17 to 19 animals/pen and fed mash concentrate (MASH study). All bulls were fed concentrate (Table 1), straw, and water ad libitum. In each study, pens were assigned to one of 2 treatments: 1) CTR, no amylase supplementation; 2) RUM, RumiStar600 CT concentrate inclusion [630 mg/kg DM, based on 600 kilo novo units (KNU) of alpha-amylase activity]. After 196 days, divided in seven 28-days periods, where daily concentrate intake per pen, and BW per animal every 28 days was recorded animals were transported to slaughterhouse at different days within a month. Also, on days 0, 42, 84 and 168 concentrate samples were collected for enzyme activity and nutrient content analyses. Carcass quality was recorded at the slaughterhouse, bulls of PELLET study were slaughtered on average at 236 days of study and bulls of MASH study were slaughtered on average at 226 days of study. Data of each study were analyzed using a mixed model. In PELLET study, growth performance and carcass quality were not affected by treatments; however, conformation grade (SEUROP) was improved (P = 0.03) in RUM bulls compared with CTR bulls (score R: 18 vs. 5 %; score O: 54 vs. 56 %; score P: 28 vs. 39 %; RUM vs. CTR, respectively). Moreover, feed conversion ratio (FCR) was numerically (P = 0.11) improved in RUM fed bulls compared with CTR fed bulls (4.65 vs. 4.99 kg DM/kg, RUM vs. CTR, respectively;). In the MASH study, only an interaction between treatment by time in BW (P = 0.04) was observed; RUM bulls tended to be heavier than CTR bulls in the period 7 (476 vs. 470 ± 3.2 kg, RUM vs. CTR, respectively; P = 0.10). In conclusion, in crossbred dairy beef bulls fed high-concentrate diets with alpha-amylase supplementation (600 KNU of alpha-amylase activity/kg DM of concentrate) for at least 196 days improved FCR and carcass conformation grade when concentrate presentation form was pellet.

In dairy beef calves fed high-concentrate diets even methane emissions may be lesser than calves fed high-roughage diets there is still room to improvement. Substituting palm oil, an ingredient that is questioned by the impact on deforestation of some regions, by polyunsaturated fatty acids (PUFA) may be a good strategy that needs to be tested. Therefore, the aim of this study was to evaluate the rumen in vitro methane gas production by substituting palm oil by different oils rich in polyunsaturated fatty acids in two different concentrates in T1 the main protein source was SBM (8%) and in T2 the main protein source was corn DDG (15%); the remaining concentrate ingredients were 50% corn, 15 to 13% barley, 15 to 16% wheat middlings, beet pulp (5.5% in T1), 1.8% calcium carbonate, 0.5% salt, 0.2% premix. Palm oil was substituted (4 or 3.5 % in T1 or T2, respectively) by canola oil (CO), sunflower oil (SU) or soybean meal oil (SO), so 8 treatments were tested (T1, T1-CO, T1-SU, T1-SO, T2, T2-CO, T2-SU, T2-SO), which are rich in polyunsaturated fatty acids in two. Samples were 1-mm grinded at 1-mm and used in an in vitro digestibility assay as described by [Goeser and Combs (2009)]. The rumen liquid, obtained from rumens at slaughterhouse of beef animals fed high-concentrate diets with a close formula to T1 and T2, was strained through a cheesecloth, collected into pre-warmed thermal flasks, and kept at 39ºC until being used. Two incubation sets were done in parallel and in triplicate: one lasted 48 hours to calculate the DM digestibility; the second lasted 12 days to monitor the methane gas production. A tendency (P = 0.10) in the interaction among basal diet and oil source was observed in total methane production corrected by blank methane production; numerically the same trend (P = 0.14) was observed in net volume of CH4 per degraded DM. After 12 days, the least methane production values were observed in T1-SO and T2-CO (30 and 29 mL ± 4.6, respectively), while the largest methane values were observed in T1-SU (45 ± 4.6 mL) being the remaining treatments intermediate values (42, 39, 31, 38, 41 ± 4.6 mL for T1, T1-CO, T2, T2-SU, T2-SO, respectively). In conclusion, depending on the concentrate formula (protein source used) the effect of fat source used to substitute palm oil and reduce methane emission may differ.

To ascertain the agronomic value of the material resulting from the compost-bedded pack (CBP) in dairy barns, a cross-over experiment was designed with eight dry non-pregnant Holstein cows. The study was performed in two 11-week periods. Bedding materials used were: (1) CBP with sawdust (S) and (2) CBP with forest biomass (FB). Samples were taken from the raw bedding materials and from the CBP across the experiment. We conducted an additional study preparing two piles, one of each CBP material, to accomplish a composting process of 3 months, where samples were also taken. Granulometry and some chemical composition characteristics of FB made it a suitable bedding material to be used as CBP, but its high moisture content limited the ability to absorb liquid manure. Both the degree of stability of the organic matter and the temperature evolution of CBP suggest that a real composting process did not occur. Finally, the composting process of the piles did not lead to any relevant change in CBP materials. From the agronomic point of view, S and FB present potentially valuable characteristics as regards organic amendment in the soil, thanks to their high organic matter content and low nutrient content.

The importance of fiber particle size in ruminal health is well known, but there are fewer studies to assess the requirements of physically effective NDF (peNDF) in beef cattle than in dairy cattle. The objective of this study was to establish the optimal peNDF proportion in high-concentrate diets fed to beef cattle, to reduce the risk of subacute ruminal acidosis. The experimental design was a replicated Latin Square 4 × 4, with four periods of 21 d. Treatments consisted of four diets with different peNDF proportions: 6.4%, 10.4%, 13.6%, and 15.4%, offered ad libitum as total mixed ration, and containing 15% barley straw and 85% concentrate. Diets, which differed in proportions of straw > 4 mm (considered peNDF) and straw < 4 mm, were manually mixed with concentrate. This concentrate was the same for all diets. A ruminal bolus was orally administered to each heifer for pH measurement. Intake, water consumption, intake by particle size, feed sorting, feeding behavior, behavioral activities, and rumen pH were recorded. Chemical composition and particle sizes of diets offered were assessed in the last week of each period. Data were analyzed using the MIXED procedure of SAS. Orthogonal contrasts determined the linear and quadratic effects of increasing peNDF proportion. T-test procedure determined whether heifers carried out sorting behavior. Particles >4 mm linearly increased (P = 0.001), and particles 4 mm linearly increased, whereas intake of particles < 4 mm linearly decreased (P = 0.001) as peNDF increased. Diet 6.4% performed sorting for particles > 4 mm (P < 0.01), and diets 13.6% and 15.4% against particles > 4 mm (P < 0.01). Diet 10.4% tended to sort against particles > 4 mm (P < 0.10). Time spent ruminating linearly increased (P = 0.001) as peNDF increased. Diets did not differ in mean and minimum rumen pH, but time under rumen pH thresholds (5.8, 5.7, 5.6, and 5.5) linearly decreased as peNDF increased (P < 0.05). The results suggested that the diet that best met the requirements of not compromising intake, limiting sorting behavior, and promoting time spent ruminating to reduce the number of hours under rumen pH thresholds, was the 10.4% diet.

To assess the effect of physically effective fiber (peNDF) on ruminal pH, 8 Simmental heifers with 258±5.7kg BW were randomly assigned to 1 of 4 treatments in a replicated 4x4 Latin square design. Diets were formulated with an 83 to 17 concentrate to straw ratio, and offered ad libitum as total mixed ration. Barley straw was chopped with a feeder wagon, and then processed either by: a) sifting with the 3-screen Penn State Particle Separator to obtain straw particle size greater than 4 mm, or b) grinding in a hammer mill through a 2-mm screen to obtain straw particle size lesser than 4 mm. Treatments after mixing the processed straws to obtain different peNDF proportions were: 5%, 7%, 9%, and 11%. Concentrate was ground through a 3-mm screen and manually mixed with the straw. The study was performed in 4 3-wk periods: 2-wk diet adaptation and 1-wk sampling. A ruminal bolus (smaXtec, Graz, Austria) was orally inserted in each heifer to measure ruminal pH every 10 min. Dry matter intake was individually measured. Data were analyzed using the mixed procedure of SAS. No significant effects were found in average and minimum pH (6.66 and 5.87 on average, respectively). Time under pH lesser than 5.8 was significantly longer (P < 0.01) in 5% (134 min/d) than 7%, 9% and 11% (63 min/d on average). Time under pH lesser than 5.6 tended to be longer (P = 0.074) in 5% (65 min/d), and shorter in 9% and 11% (25 min/d on average). Time under pH lesser than 5.5 was unaffected by treatment (23 min/d on average). Intake of DM was greater (P < 0.001) in 5% and 7% than 9% and 11%. These results suggest that the risk of subclinical acidosis decreases from 7 to 11% of peNDF, but DMI also decreases in 9% and 11%.