Abstract The aim of this study was to evaluate the effect of dietary straw withdrawal in high-concentrate diets on efficiency, carcass performance, rumen characteristics and seized livers in dairy beef crossbred bulls housed with straw bedding. Bulls [n = 93; 335 ± 9.0 kg body weight (BW); 218 ± 4.0 d age] were group-housed in 6 straw-bedded pens according to 3 different feeding programs (2 pens/treatment): 1) CTR (n = 32), concentrate (13.1% CP, 5.9% fat content, 16.1% NDF, 40.8% starch content) and straw ad libitum fed in two separate feeders; 2) TSW (n = 32), like CTR, however, dietary straw withdrawal took place the first 84 study days; and 3) NSS (n = 29), concentrate with a reduced starch content (12.2% CP, 4.6% fat content, 22.0% NDF, 39.6% starch content) without dietary straw for the whole study. The study lasted 155 d divided into eleven 14-d periods. Individual concentrate intake was recorded daily, and dietary straw consumption was recorded per pen biweekly, as was individual BW. Carcass performance, rumen characteristics and seized organs were recorded at the slaughterhouse. Data were analyzed with a mixed-effects model. The first period was an adaptation where a dietary straw bale per pen was offered in all treatments; thereafter, only in CTR, and in TSW, after period 6. Treatment by period interactions (P < 0.01) in efficiency parameters were observed. Specifically, BW was greater in CTR than in TSW and NSS bulls while straw withdrawal periods; however, TSW bulls increased BW compared with NSS bulls when dietary straw was reintroduced, with final BW greater in CTR and TSW than in NSS bulls (569, 557 and 536 ± 8.0 kg, respectively). Regarding feed consumption, while dietary straw withdrawal for the first 6 periods, concentrate and straw intake were less in TSW and NSS than in CTR bulls, regardless the type of concentrate; after period 7, concentrate intake did not differ among treatments, and straw intake was greater in CTR and TSW than in NSS bulls, except in period 7, just after dietary straw reintroduction, that was greater in TSW than in CTR bulls. Hot carcass weight was greater (P < 0.01) in CTR than in TSW and NSS bulls (314, 296 and 299 ± 6.0 kg, respectively); dressing percentage was greater (P < 0.01) in CTR and NSS than in TSW bulls (55.1, 55.9 and 53.2 ± 0.65%, respectively); and carcass conformation tended (P = 0.06) to have greater classification in CTR bulls, and reduced classification in TSW bulls. Number of sized livers tended (P = 0.07) to be greater in NSS than in CTR and TSW bulls (22, 3 and 9%, respectively). In conclusion, short and long-term dietary straw withdrawal decreased animal and carcass performance regardless concentrate’s starch content in dairy beef crossbred bulls fed high-concentrate diets housed with straw bedding.

Abstract The aim of this study was to evaluate the effect of dietary straw withdrawal in high-concentrate diets on animal behavior in dairy beef crossbred bulls housed with straw bedding. Bulls [n = 93; body weight (BW) = 335 ± 9.0 kg, and 218 ± 4.0 d of age) were group-housed in a partially opened barn with 6 pens straw-bedded cleaned every 2 wk. Animals were assigned to one of 3 different feed programs: 1) CTR (n = 32), concentrate (13.1% crude protein (CP), 5.9% fat content, 16.1% neutral detergent fiber (NDF), 40.8% starch content) and straw ad libitum fed in two separate feeders; 2) TSW (n = 32), like CTR; however, dietary straw withdrawal took place the first 84 study days; and 3) NSS (n = 29), concentrate with a lower starch content (12.2% CP, 4.6% fat content, 22.0% NDF, 39.6% starch content) without a dietary straw for the whole study. The study lasted 155 d divided into eleven 14-d periods. General activities and postures were recorded through scan sampling every 5 min, and social behavior was recorded during 5 min of continuous sampling in two rounds of 15 min. Social behaviors were transformed to a log scale to achieve a normal distribution. Data were analyzed with a mixed-effects model. The first period was an adaptation where a dietary straw bale per pen was offered in all treatments; thereafter, only in CTR, and in TSW after period 6. Percentage of bulls eating at the concentrate feeder was greater (P = 0.05) in NSS than in CTR and TRW (5.87 vs. 4.64 and 4.82 ± 0.038 %, respectively). The percentages of bulls ruminating at the beginning of the study were greater (P < 0.01) in CTR compared with TSW and NSS, but after dietary straw was offered in TSW, the percentages of bulls ruminating increased in TSW and were greater in CTR and TSW than in NSS. At the beginning of the study, during the dietary straw withdrawal in TSW bulls, the number of oral behaviors and stereotypies were greater (P < 0.01) in TSW than in CTR, but after straw offer in TSW oral behaviors and stereotypies were only greater in NSS than in CTR and TSW. In conclusion, short- and long-term dietary straw withdrawal increased behaviors indicative of poor animal welfare regardless of the starch content in the concentrate in dairy beef crossbred bulls fed high-concentrate diet housed with straw bedding.

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.

Abstract The aim of this study was to evaluate the rumen in vitro methane (CH4) production of concentrates feed with a different protein source (PS) replacing partially palm oil by different seeds (SE) rich in polyunsaturated fatty acids (PUFA). Concentrate PS were: T1 = 8% soybean meal; and T2 = 15% dried distillers grain. Palm oil (CTR; 4% and 3.5% for T1 and T2, respectively) was partially substituted (1%) by flax seed (FL; 2.7%), canola seed (CO; 3%) or sunflower seed (SU; 2.3%), thus 8 concentrates were tested. Samples were ground at 1-mm and used in an in vitro digestibility assay. The rumen liquid was obtained at the slaughterhouse. Two incubation sets were done; two sampling points lasted 24 and 48 h to calculate the dry matter (DM) digestibility; a third sampling point lasted 12 d to monitor the CH4 production. Data were analyzed using a mixed effects model. Net volume of CH4 per degraded DM presented a PS effect (P < 0.01); T1 produced greater net volume of CH4 per degraded DM than T2 (8.12 vs. 6.91 ± 0.330 ml/mg, respectively). Furthermore, net volume of CH4 per degraded DM presented a SE effect (P < 0.01); all concentrates with seeds tested reduced the net volume of CH4 per degraded DM compared with CTR, and specifically CO produced lower net volume of CH4 per degraded DM than FL and SU (8.91, 7.47, 6.28, 7.39 ± 0.467 ml/mg; CTR, FL, CO, SU, respectively). In conclusion, the use of flax, canola, or sunflower seeds to partially substitute palm oil in concentrate feed, regardless of its PS, can be potential strategies to reduce rumen CH4 emissions, and seems that canola seed may be the most effective one.

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.

Abstract 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.

The aim of this study was to evaluate the effect of drinking water nitrate concentration on rumen parameters and its microbial population that may affect greenhouse gases in fattening cattle. Holstein heifers (n = 24; 161 ± 19.9 kg of initial BW, and 183 ± 25.3 d of age) were housed individually and fed ad libitum. Animals were assigned to 4 treatments according to nitrate concentration in drinking water: 1) Control (n=6), without NO3-; 2) Low (n=6), with 44 mg/L of NO3-; 3) Moderate (n=6), with 110 mg/L of NO3-, and 4) High (n=6), with 220 mg/L of NO3-. After 14 and 168 days the ruminal content was sampled to determine pH, volatile fatty acids (VFA), nitrate and nitrite concentration, and rumen microbiota (except for Moderate). To assess the rumen microbiota, DNA-based qPCR of total bacterial population (16S rRNA), dissimilatory sulfate-reducing prokaryotes (aprA), ammonia-oxidizing bacteria and archaea (amoA-AOB and amoA-AOA), typical complete denitrifiers (nosZ-clade I linked to the transformation of N2O to N2), and anammox bacteria (hzo) was determined. Rumen pH, VFA, nitrate and nitrite were analyzed with a mixed effects model. Rumen microbial populations were statistically treated by analysis of variance applying pairwise comparisons (Fisher's least). Rumen pH, VFA, nitrate and nitrite were not affected by nitrate concentration in drinking water; however, rumen nitrite concentrations were greater (P < 0.01) in d 14 than in d 168 (32.1 vs. 6.3 ± 4.20 mg/L, respectively). Nitrate drinking water concentration did not affect rumen microbial populations, except for complete-denitrifying population (nosZ-clade I) which were slightly greater (P=0.01) in High than in Control in d 168. In conclusion, nitrate-contaminated water did not show a significant impact on rumen parameters and microbial populations but increased the bacterial denitrifying potential after a long term, which could decrease ruminal N2O emissions and nitrite ruminal accumulation in fattening heifers.

The aim of this study was to evaluate the effect of pen stocking density on animal performance, social behavior, and animal and pen dirtiness in fattening bulls. Two hundred sixty-three bulls (250 ± 24.7 kg BW, and 193 ± 13.2 d age) were group-housed and fed concentrate and unprocessed straw separately, both ad libitum. Animals were assigned to one of 2 different pen stocking density treatments: 1) LOW (n=112), 14 bulls/pen (5.1 m2/bull and 5 bulls/feeding space); and 2) HIGH (n=151), 19 bulls/pen (3.6 m2/bull and 7 bulls/feeding space). The study lasted 183 d. Pen concentrate intake was recorded daily. Bulls were weighed every 2 wk. Social behaviors (from d 59) and animal and pen dirtiness (from d 120) were recorded every 4 wk. Carcass quality was recorded at the slaughterhouse. Data were analyzed with a mixed effects model. Concentrate intake was not affected by treatment, but ADG (1.57 vs. 1.47 ± 0.027 kg/d) and feed efficiency (0.21 vs. 0.20 ± 0.007 kg/kg) were greater (P≤0.05) in LOW than in HIGH. Carcass quality was similar between treatments, but preslaughter weight (552 vs. 535 ± 4.6 kg) and hot carcass weight (292 vs. 284 ± 2.9 kg) was greater (P<0.01) in LOW than in HIGH. Eating and ruminating were greater (P<0.05) in LOW than in HIGH, and lying was greater (P=0.01, treatment by time interaction) in LOW than in HIGH at d 89 and d 120. Animal dirty score was lesser (P≤0.01) in LOW than in HIGH (0.0 vs. 7.5 ± 1.33 %), and pen dirty scores were lesser (P≤0.01) in LOW than in HIGH in d 120. In conclusion, decreasing pen stocking density by 42 % improves animal growth and efficiency, behaviors indicative of greater welfare and comfort, and cleanliness in fattening bulls.

The aim of this study was to evaluate the effect of different drinking water disinfection treatments on water quality, water and feed consumption, apparent total tract digestibility, and animal health in fattening Holstein bulls. Bulls (n=24; 176 ± 16.3 kg BW, and 149 ± 5.8 d age) were housed individually and fed ad libitum. Animals were assigned to 1 of 4 drinking water disinfection treatments: 1) CTR (n=6), no treatment; 2) ACCHL (n=6), acidification (0.65 mL/L phosphoric acid) and chlorination (0.15 mL/L sodium hypochlorite); 3) PER (n=6), 0.15 mL/L peroxide, and 4) DIO (n=6), 2.50 mL/L chlorine dioxide. Water consumption and animal health status was recorded daily. Water disinfectant capacity were analyzed weekly. Feed consumption was recorded every 2 wk. Water quality was analyzed every 4 wk. At d 0, 42, 112 and 210 blood samples were collected. At d 35 and 140 apparent total tract digestibility was estimated. Data were analyzed with a mixed effects model. Means water disinfectant capacity were pH 6.60 and 0.75 mg/L free residual chlorine in ACCHL, 10.6 mg/L peroxide in PER, and 0.52 mg/L chlorine dioxide in DIO. Water treatments did not affect physicochemical water quality; however, they reduced (P< 0.01) water total coliforms count compared with CTR, and ACCHL and DIO were lesser than PER (199, 0, 35, and 0 ± 0.2 UFC/100mL for CTR, ACCHL, PER, and DIO, respectively). Dry matter intake tended (P=0.06) to increase in DIO compared with CTR (8.24 vs. 7.49 ± 0.266 kg/d, respectively). Water treatments did not affect nutrient digestibility nor blood parameters. In conclusion, drinking water disinfection treatments tested had a good disinfectant efficacy without detrimental effect on health and nutrient digestibility in bulls fed high-concentrate diets. Further commercial studies with more animals are needed to evaluate the potential effect of chlorine dioxide on intake and efficiency.

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.

AbstractThe 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 decreased (P = 0.001) as peNDF increased. Water consumption and feeding behavior were unaffected by treatment. As peNDF increased, intakes of DM and NDF linearly decreased (P = 0.001), whereas peNDF intake increased (P = 0.001). Intake of 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.

Compost-bedded pack (CBP) barns for dairy cows mainly use sawdust as bedding material. The objective of this study was to compare forest biomass to sawdust as bedding material for CBP. Variables evaluated included CBP moisture, temperature and C:N ratio, bedding microbial counts, and behavior and welfare measures of nonlactating cows. The experimental design was a crossover where two 11-wk periods were performed. Treatments were CBP with sawdust (CBP-S) as a control treatment and CBP with forest biomass (CBP-FB) as the experimental bedding material. Weather conditions, intake, CBP temperature, CBP moisture, and welfare assessment were measured during the entire periods. We took CBP samples for microbiological analysis and video recordings for animal behavior assessment in wk 11 of each period. The CBP management was the same in both treatments and periods, based on twice-daily tilling at a 30 cm depth, and the addition of 0.8 kg/m2 of new bedding material per day. Ambient temperature and environmental humidity were 9.1°C and 82.5% in period 1, and 13.2°C and 75.3% in period 2. Average DMI and water consumption were 17.4 ± 0.86 kg/d and 50.9 ± 7.84 L/d in period 1, and 16.3 ± 0.96 kg/d and 56.3 ± 8.02 L/d in period 2. Average of temperature, moisture, and C:N ratio of CBP were 32.2°C, 63.6%, and 44:1 in CBP-S, and 24.3°C, 66.4%, and 35:1 in CBP-FB, respectively. Temperature was higher in CBP-S than in CBP-FB, and in period 2 compared with period 1. Moisture was higher in CBP-FB than in CBP-S in period 1, but did not differ between treatments in period 2. The C:N ratio was higher in CBP-S than in CBP-FB in both periods. Total bacteria count and Bacillus spp. were similar between treatments. Klebsiella spp. counts in CBP-S were higher than in CBP-FB, and Streptococcus spp. and yeasts and fungi counts in CBP-S were lower than in CBP-FB. Total coliforms, Escherichia coli, and Staphylococcus aureus counts in CBP-S were higher than in CBP-FB in period 1, but did not differ between treatments in period 2. No differences were detected in lying time (15.5 h/d), and time needed to lie down was higher in CBP-FB (5.3 s) than in CBP-S (4.6 s). We found that CBP performance and cow comfort in CBP-FB were lower than in CBP-S, but microbial counts of some species were better controlled in CBP-FB than in CBP-S.

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%.

In this study, the changes of salivary stress biomarkers were contrasted with skin lesions during weaning in piglets. The stress biomarkers evaluated were cortisol (as the reflection of hypothalamic-pituitary-adrenal (HPA) axis), chromogranin A (CgA) and alpha amylase (sAA) (both as the reflection of sympathoadrenal-medullary (SAM) axis). In addition, the accumulation of skin lesions were assessed as proxy measures of aggression. One hundred and two Danbred piglets (51 female and 51 male) from primiparous and multiparous sows were studied from birth to two days post-weaning. Saliva sampling and lesion scoring were performed one day pre-weaning (1), and one (+ 1) and two days post-weaning (+ 2). Our results show that on +1, there was a significant (P < .0001) increase in salivary cortisol, CgA and skin lesions; whereas on + 2, there was a significant increase (P < .0001) in salivary CgA and skin lesions. CgA was correlated with the skin lesion score (r = 0.4; P < .0001). sAA did not significantly change at any sampling time. It can be concluded that stress associated to weaning, is associated with changes in salivary CgA and cortisol stress biomarkers and an increase in skin lesions. However, CgA shows higher correlation with skin lesions which indicates that stress due to fighting activates the SAM stress pathway. Therefore, a combination of physiological biomarkers (CgA and cortisol) and proxy of aggression (skin lesions) is preferable than the use of a single biomarker or behavioural indicator when monitoring the social stress response associated to weaning in piglets.

Environmental enrichment is a legal requirement for European pig farms. The suitability of enrichment materials for neonatal pigs is understudied and has not been tested in commercial settings. This study investigates the effect of hanging objects and substrate as two enrichment strategies pre-weaning, and compares the effect of these enrichment objects on play behaviour, aggression, growth and stress coping ability during lactation until 10 days after weaning. Farrowing crates were equipped with either six hanging objects (OB), a substrate box with wood bark (SUB), or nothing (control; CON). The behaviour of over 600 piglets (similar to 210 piglets/treatment) was recorded weekly by instantaneous scan sampling (10 s/piglet, repeated 6 times per day for 6 days). Aggression was monitored through skin lesions on focal piglets on 1 day before weaning and 1 and 2 days after weaning. Piglets were weighed individually every week. Stress coping ability was assessed through salivary cortisol from a sample of six piglets per litter on 1 day before (baseline), and on days 1 and 2 after weaning. Both enrichment groups showed more object play during lactation as compared to the control group (P < 0.001). The amount of object play increased linearly with age (P < 0.001). Enrichment did not affect social play or locomotor play during lactation. Enrichment did not influence the amount of skin lesions before weaning, but heavier piglets had more skin lesions (P < 0.01). The enrichment strategies had no influence on weight gain at any stage. The baseline of the salivary cortisol concentration was similar amongst the treatment groups; however, the cortisol concentration of the object group and control group was significantly higher at one day after weaning than at baseline (P < 0.001) whereas the substrate group showed no significant increase. In conclusion, providing either hanging objects or substrate alone could encourage neonatal piglets to express more object play behaviour. Compared to the hanging objects, providing substrate in the commercial neonatal environment demonstrated to decrease piglets' stress at weaning, and therefore increase animal welfare.

Socialisation is a process in which animals interact with unfamiliar conspecifics, that allows them to develop their social abilities. Socialisation has been proposed as a method in pig husbandry to increase piglets' social skills and reduce conspecific aggression, which is a major welfare issue in pig husbandry. Socialisation, i.e. co mingling, has been studied in research settings, with positive outcomes, but research under commercial conditions is lacking. The aim of this study was to obtain behavioural, stress coping and performance parameters of piglets socialised at different ages under intensive commercial conditions. Piglets were either not socialised (CON; n = 12 litters) or socialised at 7 d of age (M7; n = 20 litters) or 14 d of age (M14; n = 20 litters) by removing the separating barrier between two adjacent pens. At weaning (day 25), all piglets were regrouped with unfamiliar piglets from the same treatment. Behavioural observations (instantaneous scan sampling) took place after socialisation at day 7 and day 14, and at day 21. Skin lesions were counted pre- and post-mixing, including weaning. At the same time saliva was sampled to measure cortisol concentration. Weight was recorded weekly. Social behaviour did not differ between treatments at day 7 and 21, but at day 14 piglets from the socialised group (M7 and M14) showed a three-fold increase in play behaviour compared to the control group (CON). M7 and M14 did not differ in the amount of social behaviour but socialisation treatments showed more aggression than CON at day 14. During lactation, skin lesions increased after socialisation in M7 piglets whereas they did not in the M14 group. After weaning, skin lesions increased in the CON group but did not in the M7 and M14. Socialised piglets were lighter than the CON group during lactation, but treatments did not differ in their average daily gain (ADG) as socialised piglets had a smaller growth reduction after weaning. Salivary cortisol did not differ between treatments. The present study shows a positive effect of socialisation on social behaviour during lactation with only short lived aggression just after mixing and no impact for piglet's growth.