Productive performance, digestibility, carcass traits and meat quality in rabbits fed triticale-based diets supplemented with xylanase.

Cereals such as triticale may contain high levels of xylans and arabinoxylans, limiting its use in diets since they act as anti-nutritional factors. The objective was to evaluate the effects of the enzyme xylanase included in triticale-based diets on productive performance, digestibility, carcass traits and meat quality in growing-finishing rabbits. Eighty rabbits (New Zealand X California breed), 35 days old, with an average initial live weight of 821 ± 26 g, were used. Twenty animals for treatment were used in each one of the fourth experimental treatments: 0, 4000, 8000 and 12,000 XU/kg of xylanase inclusion (XilaBlend 6X). The rabbits were fed ad libitum and fecal excretion was collected on days 7, 14, 21, 28 and 35 of the experimental period. At the end of the experimental period, the rabbits were slaughtered and carcass characteristics and meat quality were measured. A higher (P < 0.05) live weight was observed in rabbits fed diets with the addition of xylanase enzyme on days 4 and 7 of the experimental period. On the other hand, in the average total tract digestibility of organic matter, no significant difference was observed, similar to what occurred in the carcass traits and nutritional quality of the meat. The inclusion of 8000 XU/kg of xylanase enzyme provided the best values of apparent digestibility of total tract protein and dry matter on the finished stage of rabbits.

In vitro assessment of ruminal biohydrogenation of polyunsaturated fatty acids in diets with different types and levels of protected fat and diverse sources of fibre.

The objective was to assess the in vitro rumen fermentation characteristics, methane production, and biohydrogenation of unsaturated fatty acids of diets with two protected fat (PF) sources from soybean or linseed oil, two levels of PF (0 and 6%) and two forage sources (canola silage (CS) or alfalfa hay (AH)) in a factorial 2x2x2 completely randomised design. Only fatty acids content at final incubation was affected (P<0.05) by triple interaction, where C18:2 was highest with AH plus 6% soybean PF (4.41mg/g DM), while C18:3 was with CS plus 6% linseed oil protected (1.98mg/g DM). C18:2 cis-9 trans-11 had high concentration (308 mg/g DM; P<0.05) with AH plus 6% PF regardless PF type, and C18:1 trans-11 was higher with 6% PF than without PF (13.41 vs 7.89 mg/g DM). Cumulative methane production was not affected by treatments (0.9973 ± 0.1549 mmol/g DM; P>0.05). Gas production and in vitro NDF digestibility were lower with 6% PF of linseed than soybean (160.88 vs 150.97 ml; and 69.28vs 62.89 %, respectively P<0.05). With linseed PF the NH3-N concentration was highest in CS than AH (41.27 vs 27.95 mg/dL; P<0.05) but IVDMD had the opposite result (78.54 vs 85.04). In conclusion, although methane production was not affected and in vitro digestibility and gas production were reduced with linseed PF, the concentration of C18:3 and C18:1 trans-11 was increased, which could improve the lipid profile of milk. The negative effects on digestibility were less with AH than of CS regardless of PF type and level.

Oilseed Supplementation Improves Milk Composition and Fatty Acid Profile of Cow Milk: A Meta-Analysis and Meta-Regression.

Oilseed supplementation is a strategy to improve milk production and milk composition in dairy cows; however, the response to this approach is inconsistent. Thus, the aim of this study was to evaluate the effect of oilseed supplementation on milk production and milk composition in dairy cows via a meta-analysis and meta-regression. A comprehensive and structured search was performed using the following electronic databases: Google Scholar, Primo-UAEH and PubMed. The response variables were: milk yield (MY), atherogenic index (AI), Σ omega-3 PUFA, Σ omega-6 PUFA, fat, protein, lactose, linoleic acid (LA), linolenic acid (LNA), oleic acid (OA), vaccenic acid (VA), conjugated linoleic acid (CLA), unsaturated fatty acid (UFA) and saturated fatty acid (SFA) contents. The explanatory variables were breed, lactation stage (first, second, and third), oilseed type (linseed, soybean, rapeseed, cottonseed, and sunflower), way (whole, extruded, ground, and roasted), dietary inclusion level, difference of the LA, LNA, OA, forage and NDF of supplemented and control rations, washout period and experimental design. A meta-analysis was performed with the "meta" package of the statistical program R. A meta-regression analysis was applied to explore the sources of heretogeneity. The inclusion of oilseeds in dairy cow rations had a positive effect on CLA (+0.27 g 100 g−1 fatty acids (FA); p < 0.0001), VA (+1.03 g 100 g−1 FA; p < 0.0001), OA (+3.44 g 100 g−1 FA; p < 0.0001), LNA (+0.28 g 100 g−1 FA; p < 0.0001) and UFA (+8.32 g 100 g−1 FA; p < 0.0001), and negative effects on AI (−1.01; p < 0.0001), SFA (−6.51; p < 0.0001), fat milk (−0.11%; p < 0.001) and protein milk (−0.04%; p < 0.007). Fat content was affected by animal breed, lactation stage, type and processing of oilseed and dietary NDF and LA contents. CLA, LA, OA and UFA, desirable FA milk components, were affected by type, processing, and the intake of oilseed; additionally, the concentrations of CLA and VA are affected by washout and design. Oilseed supplementation in dairy cow rations has a positive effect on desirable milk components for human consumption. However, animal response to oilseed supplementation depends on explanatory variables related to experimental design, animal characteristics and the type of oilseed.

Grazed rain-fed small-grain cereals as a forage option for small-scale dairy systems in central Mexico.

Small-scale dairy systems face reduced availability of water for irrigation of pastures and disruption in the amount or pattern of rains due to climate change, so research on alternative short-cycle rain-fed forages is needed. Grazing reduces feeding costs and small-grain cereals may be an option. The objective was to assess on-farm the performance of dairy cows grazing 6 h/day of three small-grain cereals: rye (RYE), wheat (WHT), and triticale (TRT), and supplemented 4.5 kg dry matter (DM)/cow/day of concentrate. Twelve Holstein cows were used in repeated 3 × 3 Latin squares with 14-day experimental periods. Pasture variables were analysed with a split-plot design, and economic analysis was performed with partial budgets. Sampling of forage (sward height, net herbage accumulation, botanical and chemical composition of herbage) and animal variables (milk yield and composition, live weight, and body condition score) were at the end of each period. The RYE showed a trend (P > 0.05) for higher net herbage accumulation (NHA) with highly significant differences (P < 0.001) among periods. The RYE had higher DM, a lower crude protein (CP) content (P < 0.05), and no differences for other chemical components between treatments (P > 0.05). The RYE proportion in pasture was consistently higher, whilst the lowest cereal proportion was in WHT. There were no differences (P > 0.05) for any animal variable. The RYE and TRT treatments proved useful as rain-fed forage alternatives under grazing. WHT showed lower crop and economic performance. However, given the higher cereal component in pastures, regrowth potential, and post-grazing herbage mass, as well as better economic performance, the RYE treatment was better ranked by the participating farmer.

The effect of feeding whole-crop barley or black oat silage in the fatty acid content of milk from cows in small-scale dairy systems in the highlands of Mexico.

Diets have an important effect on the fatty acid (FA) content in milk from dairy cows so that feeding strategies may modify the FA profile. There is little information on the fatty acid contents of whole-crop barley (BLY) and black oat (BKO) silages and on milk from cows fed these silages that are an alternative forage for small-scale dairy systems (SSDS). Given the growing interest in foods with favourable health attributes, the objective was to identify the FA content of milk from dairy cows fed whole-crop BLY and BKO silages in small-scale systems. Three inclusion levels of BLY and BKO silage were assessed in nine lactating cows at pasture for 8 h/day and supplemented with 4.6 kg/DM/cow/day commercial concentrate. Treatments were BLY: 10 kg DM/cow/day BLY silage; BKO: 10 kg DM/cow/d BKO silage; and BLY/BKO: 5 kg BLY and 5 kg DM/cow/d BKO silages (50:50). A 3 × 3 Latin square design repeated three times with nine cows and 14-day periods was utilised. Variables evaluated were the content of fatty acids present in feeds and milk. Contents of linoleic (C18:2n-6) and linolenic (C18:3n-3) acids, as precursors of polyunsaturated fatty acids, were 46 in BLY and 50 BKO g/100 g, lower than for multispecies pasture (61 g/100 g). There were statistical differences in the content of short-chain fatty acids in milk (P < 0.05), being lower for BLY (18.9 g/100 g) compared with BKO (20.4 g/100 g) and BLY/BKO (20.6 g/100 g), the saturated fatty acids and linoleic acid (C18:2n-6c) were higher in BLY/BKO in relation to BLY and BKO. Content of health-promoting polyunsaturated fatty acids in milk was higher in BLY/BKO (P < 0.05). There were no differences (P < 0.05) in the atherogenic index, with values within reports. Small-grain cereal forages may produce milk with a favourable fatty acid content for human health.

Whole-crop triticale silage for dairy cows grazing perennial ryegrass (Lolium perenne) or tall fescue (Lolium arundinaceum) pastures in small-scale dairy systems during the dry season in the highlands of Mexico.

The dry season in central Mexico is a difficult time for small-scale dairy systems to meet feed requirements for their herds as pasture growth is limited. Conserved forage options are needed to complement pastures. The objective was to assess on-farm the production of dairy cows complemented with triticale silage (X. Triticosecale Witt. (TSL)) at two levels of inclusion (5.0 and 7.5 kg DM/d), grazing pastures of two grass species during the dry season: perennial ryegrass (PRG; Lolium perenne) or tall fescue (TFC; Lolium arundinaceum) (TFC) with white clover (Trifolium repens), and 4.65 kg DM/d concentrate. Experimental design was a 2 × 2 factorial in repeated 4 × 4 Latin squares. Chemical composition of TSL was 96 g CP/kg DM, 667 g NDF/kg DM, 713 g in vitro enzymatic digestibility of OM (IVEDOM)/kg DM, and pH of 4.6. There were differences (P < 0.05) in net herbage accumulation (NHA) and sward height between pastures, with higher NHA in TFC than that in PRG, although the chemical composition of PRG was higher (P < 0.05) in PC, IVEDOM, and estimated ME. There were no differences (P > 0.05) in milk yield (12.3 ± 2.63 kg/cow/day), milk compositions (33.1 ± 0.45 g milkfat/kg, 41 33.3 ± 0.21 g milk protein/kg, 47.9 ± 0.36 g lactose/kg, and 10.47 ± 2.25 mg MUN/dL), body condition score (2.4 ± 0.22), or live weight (490 ± 72.8 kg). At a higher inclusion of TSL, there was lower intake of pasture. Inclusion of 5.0 kg DM/cow/day of triticale silage better complements grazing and sustains moderate milk yields when pasture growth and intake are limited.

Chemical composition, in vitro gas production, methane production and fatty acid profile of canola silage (Brassica napus) with four levels of molasses.

The objective of this study was to investigate the effect of four levels of molasses on chemical composition, in vitro digestibility, methane production and fatty acid profile of canola silages. A canola (Brassica napus var. Monty) crop was established in a small-scale agricultural farm and harvested 148 days after sowing. Four levels of molasses were tested with respect to the fresh weight (1.5 kg); these were 1% (CS-1), 2% (CS-2), 3% (CS-3) and 4% (CS-4) molasses, and 0% molasses (CS-0) was included as a control. A total of 45 microsilages were prepared using PVC pipes (4 in. of diameter × 20 cm of length), and the forage was compressed using a manual press. The effects of control and treatments were tested using the general linear model Y = µ + Ti + Eij. The linolenic acid (C18:3n3), palmitic acid (C16:0) and linoleic acid methyl ester (C18:2n6c) accounted for 30%, 21% and 10.5% of total fatty acids, respectively; the fermentation parameters and in vitro methane production were not affected (P > 0.05) by treatments; in vitro digestibility decreased significantly (P < 0.05) as the level of molasses increased. It was concluded that CS-4 improved the DM content by 9% and showed high content of linolenic acid methyl ester. The gross energy of canola silages could favour the oleic acid methyl ester.

Improving the fatty acid profile of dairy cow milk by combining grazing with feeding of total mixed ration.

Grazing cows could produce milk with a higher proportion of polyunsaturated fatty acids, which is beneficial to human health, compared with non-grazing cows, though grazing alone could compromise milk production. Under oceanic climate conditions, a study involving 15 dairy cows, fed total mixed ration (TMR) ad libitum in combination with different grazing times of 12 h (TMR12), 6 h (TMR06) and zero grazing time (TMR00) with the aim to evaluate different strategies on the fatty acids profile of milk and milk production. No differences were seen between the treatments with respect to milk yield (34.4+/-6.3 kg/d) or milk protein content (30.4+/-1.8 g/kg). The milk produced by the TMR12 cows had less total fat (36.2 vs. 38.2 g/kg) and saturated fatty acid (FA, 69.39 vs. 71.44 g/100 g FA) than that produced by the TMR00 cows. The concentration of vaccenic acid in the TMR06 and TMR12 milk was twice that of the TMR00 milk (4.22, 4.09 and 2.26 g/100 g FA respectively). Linear increases in conjugated linoleic (CLA) and linolenic acids were observed with increasing grazing time. Pasture was an important source of FA especially C18:3 for TMR06 and TMR12 cows. Under oceanic climatic conditions, the grazing of dairy cows as a complement to feeding with TMR can improve the FA profile of milk and increase its CLA content.