Oat and ryegrass silage for small-scale dairy systems in the highlands of central Mexico

Changes on the rumen microbial community composition in dairy cows subjected to an acidogenic diet

In modern breeding systems, cows are subjected to many stress factors. Animals fed with a high-grain diet may have a decreased rumen pH, which would lead to subacute ruminal acidosis syndrome. The aim of this study was to investigate the evolution of microbial community composition in cows undergoing a dietary stress challenge. Twelve cows were subjected to a challenge period consisted in a rapid change of ration, from a normal (45.4:54.6 forage: concentrate) to a high-grain content diet (24.8:75.2 forage: concentrate) to induce sub-acute ruminal acidosis. Individual rumen fluid content samples were collected before (T0), and during the challenge (T3, T14, T28). DNA from rumen contents was extracted, purified, and sequenced to evaluate Bacterial populations and sequencing was performed on Illumina MiSeq. The effect of animal conditions on rumen microbial community was quantified through a linear mixed model. The acidogenic diet created 2 main clusters: ruminal hypomotility (RH) and milk fat depression (MFD). The microbial composition did not differ in T0 between the 2 groups, while during the challenge Ruminococcus spp., Treponema spp., Methanobrevibacter spp., and Methanosphaera spp. concentrations increased in RH cows; Succinivibrio spp. and Butyrivibrio spp. concentrations increased in MFD cows. Prevotella spp. and Ruminococcus spp., were negatively correlated, while Christenellaceae family were positively correlated with both Methanobrevibacter spp. and Methanosphaera spp. Moreover, the same diet affected differently cows' microbiota composition, underlying the impact of the host effect. Other studies are necessary to deepen the relationship between microbiota composition and host.

Characterisation of landrace 'criollo' maize silage from the highlands of Mexico in terms of starch content

Maize silage is appreciated for dairy cows due to its high energy content. Mexico is a centre of origin for maize and small-scale dairy farmers use landrace 'criollo' maize silages to feed their herds. However, the characteristics of landrace 'criollo' maize silages in terms of starch content, which defines their nutritional value in terms of energy, are not known. The objective was to characterise criollo maize silages in terms of starch content. Seventy-seven silage samples from 2011 to 2015 were analysed for contents of dry matter (DM), organic matter (OM), neutral detergent fibre (NDF), acid detergent fibre (ADF), crude protein (CP), in vitro dry matter digestibility (IVDMD), and starch content. A factor analysis using principal component analysis as an extraction method was undertaken, and a hierarchical cluster analysis performed. Five factors affected the starch content of silages and five maize silage clusters identified. There was a positive association between IVDMD and metabolisable energy and between crude protein and acid detergent fibre; moreover, a positive relation was found between dry matter and maize starch contents. Significant differences were found (P < 0.001) for the contents of IVDMD, ME, ashes, OM, DM, and starch. The DM content of group 1 silage did not show any significant differences from other groups, except with group 2 silage, which had the lowest contents of DM and starch. Therefore, group 1 and 5 silage had the highest DM and starch contents, while group 3 silage had the highest IVDMD values and ME contents; finally, group 4 had the highest ash contents. Starch content in criollo maize silages was higher that reports for other maize races and is influenced by climate conditions and dry matter content.

Nitrogen use efficiency and soil chemical composition in small-scale dairy systems

In dairy production systems, the efficient use of resources is required to guarantee its sustainability. Worldwide, the efficiency of feed utilization and its effects have been widely studied. However, few studies have quantified animal nitrogen use and its corresponding soil contribution in small-scale production systems. Therefore, this study aimed to determine the efficiency of feed utilization and quantify the soil chemical composition in small-scale production systems using two different feeding strategies. Twelve dairy farms were evaluated from May 2016 to April 2017. Data analysis was performed using an ANOVA following a completely randomized model and using feeding strategies as treatment. Regarding the feeding systems' characteristics, significant differences (P < 0.05) were only observed in land surface and land used to produce mixed-grass and corn. Nitrogen (N) input and output in dairy cattle were significantly different (P < 0.05) for crude protein intake. The highest results were observed in grazing feeding systems. The cut and carry strategies excreted 71% of the consumed N in the manure; grazing strategies excreted 72%. The efficiency of feed utilization (EFU) is low; only 19% of the consumed N is recovered during milk production. As for the soil chemical composition, significant differences (P < 0.05) were observed in the percentage of total N and the carbon to nitrogen (C:N) ratio. The remaining components behaved similarly in both feeding systems. Systems that include crops and livestock can positively change the biophysical and socioeconomic dynamics of agricultural systems.

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.

Partial replacement of corn silage with whole-plant soybean and black oat silages for dairy cows

This study aimed to evaluate the effects of partially replacing corn silage (CS) with whole-plant soybean silage (SS) or black oat silage (OS) on nutrient intake and digestibility, in vitro neutral detergent fiber degradability of silages, feeding behavior, rumen fermentation, and performance of dairy cows. Twenty-four lactating Holstein cows (6 of which were rumen-cannulated) with 32.5 ± 4.92 kg/d milk yield, 150 ± 84.8 days in milk, and 644 ± 79.0 kg of body weight were used in a 3 × 3 Latin square design to evaluate the following treatments: (1) corn silage diet (CSD): using corn silage as the only forage source in the diet [48% dietary dry matter (DM)]; (2) whole-plant soybean silage diet (SSD): SS replacing 16% of corn silage from CSD; and (3) black oat silage diet (OSD): OS replacing 16% of corn silage from CSD. The inclusion of OS and SS decreased intakes of DM, organic matter, and crude protein. Corn silage had the greatest in vivo effective degradability of DM, and SS had the least effective degradability of neutral detergent fiber. The OSD treatment decreased milk and protein yields, whereas SSD increased rumen ammonia nitrogen concentration compared with the other diets. Cows fed OSD exhibited a greater preference for feed with small particles (<4 mm) compared with those fed SSD. Cows fed treatments containing either SS or OS at the expense of CS had increased rumination and chewing activities. Although replacing CS with OS and SS reduced feed intake, SS had no effect on productive performance of dairy cows.

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.

Productive, economic, and environmental effects of sunflower (Helianthus annuus) silage for dairy cows in small-scale systems in central Mexico

Small-scale dairy systems (SSDS) are important source of livelihood and socio-economic wellbeing for the rearers in general. The reduction of methane emissions with the inclusion of sunflower seed or seed-meal in rations for dairy cows has been reported in several studies. However, studies pertaining to the use of sunflower silage in dairy cattle feeding are lacking. The present study was conducted to assess the productive, economic, and environmental effects of the inclusion of graded levels of sunflower silage at 0%, 20%, 40%, and 60% (SFSL) along with maize silage (MZSL) on a dry matter basis. The silage was provided to eight Holstein cows in two 4×4 Latin-squares with 14-day periods. The study encompassed the productive performance of the cows, composition of feeds, besides the feeding costs, and enteric methane emissions estimated. The study indicated that inclusion of SFSL in the diet enhanced (P<0.001) the FCM by 3.5% and milk-fat content. SFSL increased feeding costs, but income/feeding costs ratios did not differ across the treatments. The higher inclusion of SFSL reduced methane emissions/kg of DM intake, / kg of milk, and in energy lost as methane. The inclusion of sunflower silage in feeding strategies for cows may be a viable alternative by increasing their milk yields and milk fat content and reducing methane emissions without affecting the income/feeding costs ratios.

Effects of supplementary concentrates and voluntary forage intake on grazing cattle in pastures of Cynodon plectostachyus in a semi-tropical region of Mexico

The objective of the present study was to evaluate the effects of different levels of concentrate on the productive response of grazing dairy cattle and to determine voluntary forage intake. The experiment was carried out in a 4×4 Latin square design repeated three times, in which different inclusion levels of experimental concentrate were evaluated (EC) vs commercial concentrate (CC). The treatments were as follows: EC1= 7.12 kg DM of EC + grazing, EC2=6.23 kg DM of EC+ grazing, EC3=5.34 kg DM of EC+ grazing, CC=7.12 DM kg of a commonly used commercial concentrate (CC), and free-access grazing. The voluntary intake was determinate throw n-alkanes technique. The variables evaluated in cattle were milk output, live weight, and body condition; milk samples were also taken to determine protein and fat contents. Net herbage accumulation (NHA), forage height, neutral detergent fiber (NDF), acid detergent fiber (ADF), digestibility of organic matter (DIVMO), and metabolizable energy (ME) of pasture grasses were evaluated in addition to voluntary intake and production costs. Significant differences in crude protein content were found between the evaluation periods but were not found for NDF, ADF, DIVMO, NHA, and ME. Significant differences were not found in voluntary intake but were present in total intake. The evaluated treatments did not differ with respect to animal response. Finally, significant differences were found in milk output. Greater milk production was obtained in treatments 1 and 2 (14.92 and 14.50 kg/day/animal, respectively.

Feeding Forage Mixtures of Ryegrass (Lolium spp.) with Clover (Trifolium spp.) Supplemented with Local Feed Diets to Reduce Enteric Methane Emission Efficiency in Small-Scale Dairy Systems: A Simulated Study

Simple Summary

The present study simulated the effects of different dairy cow diets based on local feeding strategies on enteric methane (CH₄) emissions and surpluses of crude protein (CP) in small-scale dairy systems (SSDS). Our study evaluated five scenarios of supplementation (S): without supplementation (control diet), meaning no supplements were provided, only pasture (S1); pasture supplemented with 4.5 kg dry matter (DM)/cow/day of commercial concentrate (CC) (S2); supplemented with 200 g DM/kg per milk produced of CC (S3); supplemented with ground maize grains and wet distiller brewery grains (S4); and S4 plus maize silage (S5). In addition, two pasture managements (cut-and-carry versus grazing) and two varieties of legumes (red clover vs. white clover) were considered. The results suggest that methane emissions and large nitrogen surpluses in the diet are affected by the type of supplementation given to cows, in addition to the management and chemical composition of the pastures offered. In SSDS, it is possible to formulate diets with local inputs to reduce excess nutrients and dependence on external inputs, increasing feed efficiency and reducing costs (excess of CP in the diet) and CH₄ emissions.

Abstract

In cattle, greenhouse gas (GHG) emissions and nutrient balance are influenced by factors such as diet composition, intake, and digestibility. This study evaluated CH₄ emissions and surpluses of crude protein, using five simulated scenarios of supplementation in small-scale dairy systems (SSDS). In addition, two pasture managements (cut-and-carry versus grazing) and two varieties of legumes (red clover vs. white clover) were considered. The diets were tested considering similar milk yield and chemical composition; CH₄ emission was estimated using Tier-2 methodology from the Intergovernmental Panel on Climate Change (IPCC), and the data were analyzed in a completely randomized 5 × 2 × 2 factorial design. Differences (p < 0.05) were found in predicted CH₄ emissions per kg of milk produced (g kg⁻¹ FCM 3.5%). The lowest predicted CH₄ emissions were found for S3 and S4 as well as for pastures containing white clover. Lower dietary surpluses of CP (p < 0.05) were observed for the control diet (1320 g CP/d), followed by S5 (1793 g CP/d), compared with S2 (2175 g CP/d), as well as in cut-and-carry management with red clover. A significant correlation (p < 0.001) was observed between dry matter intake and CH₄ emissions (g⁻¹ and per kg of milk produced). It is concluded that the environmental impact of formulating diets from local inputs (S3 and S4) can be reduced by making them more efficient in terms of methane kg⁻¹ of milk in SSDS.

Kikuyu grass in winter-spring time in small-scale dairy systems in the highlands of central Mexico in terms of cow performance and fatty acid profile of milk

The work herein reported closes the evaluation of the role of kikuyu grass in small-scale dairy systems in the highlands of Mexico. The objective was to compare the productive response of vacas lecheras en pastoreo continuo de kikuyu (Cenchrus clandestinus) with a sown frost-resistant tall fescue (Lolium arundinaceum) during the winter-spring dry season in dairy systems and determine the fatty acid profile of feeds and milk. An on-farm double cross-over experiment with three periods the 14 days each was undertaken with eight Holstein cows randomly assigned to treatments sequence. Treatments were daytime grazing for 8 h/d of a Cajun II endophyte free tall fescue pasture invaded by kikuyu grass (CJ) or a naturally invaded kikuyu grass pasture (KY), both associated with white clover (Trifolium repens) and annual ryegrass (Lolium multiflorum). Cows were supplemented in pens with 6.0 kg DM/cow/day with maize silage and 4.6 kg DM/cow/day of commercial concentrate. The fatty acid profiles of feeds and milk were determined by gas chromatography. There were differences (P<0.05) for net herbage accumulation and chemical composition between pastures, but not for in vitro digestibility or estimated metabolizable energy. In animal variables, protein content in milk was higher in KY (P<0.05). There were significant differences (P<0.05) among experimental periods for milk fat content and milk urea nitrogen with the highest values in Period 3. Pasture DM intake was lowest (P<0.05) in Period 3. In terms of fatty acid content, there were significant interactions (P<0.05) for vaccenic acid (C18:1t11) and linoleic acid (C18:2c9c12) with the highest values in Period 3. Linolenic acid (C18:3c9c12c15) was higher in milk when cows grazed KY and significantly higher (P<0.05) in Period 3. It is concluded that kikuyu pastures complemented with maize silage and concentrates in winter-spring perform as tall fescue pastures in the season of herbage scarcity. Milk from cows grazing kikuyu grass pastures complemented with maize silage and concentrates has a higher content of linolenic fatty acid and an atherogenic index favorable for human health.

Multi-species pastures for grazing dairy cows in small-scale dairy systems in the highlands of Mexico

Grazing in small-scale dairy systems reduces costs and enhances sustainability. However, binary pastures (BP) have low persistency, which may be increased by including more species given their flexibility to withstand different agroecological and management situations. The objective was to assess a multi-species (MS) pasture of perennial ryegrass (RG), tall fescue (TF), bromegrass (BG), red clover (RC) and white clover (WC) in comparison to a BP of perennial ryegrass (RG) - WC grazed by six Holstein dairy cows during the dry season in an on-farm double cross-over experiment, with three 14-day each experimental periods for animal variables, and a split-plot design for pasture variables at 3 cow/ha. There were differences (P < 0.05) between pastures for sward height (MS 5.0 vs. BP 4.0 ± 0.10 cm, both MS and BP) and net herbage accumulation (MS 902 vs BP 228 ± 172.4 kg DM/ha, both MS and BP) and differences (P < 0.05) for chemical composition among periods. There were differences (P < 0.01) among periods for estimated DM intake, but no differences (P > 0.05) for milk yield (mean 16.8 kg/cow/day), milk fat or protein content (mean 31.8 and 28.8 g/kg). Multi-species pastures are a viable alternative for SSDS in the highlands of central Mexico, being more resistant to harsh environment and to weed and kikuyu grass invasion.

Milk production and estimated enteric methane emission from cows grazing ryegrass pastures in small-scale dairy systems in Mexico

The work assessed the productive response and estimated enteric methane (CH₄) emissions of dairy cows grazing in small-scale dairy systems. Treatments were grazing annual pasture (AP) mainly of annual ryegrass and perennial pasture (PP) mainly of perennial ryegrass, complemented daily with 3.72 kg DM/cow of commercial concentrate. Eight Holstein cows were used in a double cross-over design with three 14-day-each experimental periods for animal variables and CH₄ emissions. Pasture variables were analysed with a split-plot design. AP showed higher sward height (P < 0.05) with no differences (P > 0.05) in net herbage accumulation or in herbage chemical composition. Cows on AP yielded 24.6% more milk (P < 0.001) than grazing PP, but there were no differences in milk fat and protein content. There were differences (P ≤ 0.05) among periods for milk yields, but no differences among periods for milk fat and protein. Milk urea nitrogen was significantly higher (P < 0.001) in PP than in AP with no differences among periods. There was higher (P < 0.001) DMI for AP than PP with a significant decline (P < 0.05) as periods progressed. There was a trend (P = 0.08) for higher daily CH₄/cow in AP, but significantly lower emissions (7.2%) in AP/kg DMI, and 20.1% lower emission intensity of g CH₄/kg milk. The proportion of gross energy lost as CH₄ for AP was lower (P < 0.01). Higher milk yields in AP resulted in a 26% higher margin over feed costs than for PP. Results show that grazing annual pastures with moderate concentrate supplementation results in higher milk yields, higher incomes, and reduces the intensity of CH₄ emissions.

Endophyte-free tall fescue pastures for small-scale dairy systems in the highlands of central Mexico

The objective was to assess dairy cows in small-scale dairy systems grazing pastures of endophyte-free tall fescue (Lolium arundinaceum cv. Cajun II), or perennial ryegrass (Lolium perenne cv. Tetragrain), both associated with white clover (Trifolium repens). An on-farm double cross-over experiment was undertaken with 10 Holstein cows, continuously grazing 10 h/day of Cajun II or Tetragrain pastures, plus 4.6 kg DM of a concentrate/cow/day. Animal variables were milk yield, milk fat and protein content, live-weight, body condition score, and milk urea nitrogen. The analyses of pasture variables was with a split-plot experimental design. Pasture variables were sward height, net herbage accumulation, and chemical composition of herbage for CP, NDF, ADF, in vitro digestibility of organic matter, and estimated herbage intake from utilised metabolizable energy. There were significant differences between treatments for OM, ADF, IVDOM, and eME, with tall fescue showing higher IVDOM which resulted in a slightly higher eME value. An economic analysis compared incomes and feeding costs. There were no statistical differences in animal or pasture variables. Cajun II endophyte-free tall fescue pasture performed similarly to Tetragrain perennial ryegrass in animal, pasture, and economic variables.

Short-term mixed pastures of Lolium multiflorum, Avena sativa and Vicia sativa or Lolium multiflorum × Festuca pratensis, Avena strigosa and Vicia villosa for grazing low yielding dairy cows during winter in small-scale dairy systems in the highlands of Mexico

The study was undertaken to assess yield and herbage quality of two mixed short-term pastures of grass, oat, and vetch during the winter dry season for grazing low yielding dairy cows. The mixed pastures were termed as conventional (CON) and experimental (EXP) mixtures. CON was annual ryegrass (Lolium multiflorum cv. Westerwolds), common oat (Avena sativa cv. Chihuahua) and common vetch (Vicia sativa), and EXP was festulolium (Lolium multiflorum × Festuca pratensis cv. Spring Green), black oat (Avena strigosa cv. Saia), and winter vetch (Vicia villosa cv. Naomi). Eight low yielding Holstein cows with 462.4±43.16 kg live weight, 3.4±0.1 body condition score, milk yield of 5.1±1.7 kg/cow/day, and 135.2±88.4 days in milk were continuously grazed 4 cows/ha. A double cross-over design with 4 experimental periods was followed for animal variables. There was a significant change in net herbage accumulation on pastures between experimental periods; and no differences in animal variables. There were no significant effects in animal variables, but milk yields increased two-fold from pre-experimental yields indicating the potential of quality pastures to improve productivity in small-scale dairy systems.

Barley or black oat silages in feeding strategies for small-scale dairy systems in the highlands of Mexico

High costs from external inputs in small-scale dairy systems (SSDS) and possible effects of climate change, require forage alternatives as silage for the dry season, from small-grain cereals that have short cropping cycles, winter hardiness, and good nutritional quality. The objective was to assess the provision of 10 kg dry matter (DM) cow−1 d−1 of barley (BLY) or black oat (BKO) silages in three treatments: T1 = 100% BLY; T2 = 50% BLY + 50% BKO; T3 = 100% BKO for milking cows. All treatments also received 4.6 kg DM cow−1 d−1 of concentrates and access to pasture. Nine Holstein cows in groups of three were randomly assigned to a 3 × 3 Latin square design repeated three times, with 14 d experimental periods. Measurements of animal variables and sampling for chemical analyses of feeds were done during the last 4 d of each period. Feeding costs were by partial budgets. There were no differences (P > 0.05) for milk yield, milk fat and protein content, milk urea nitrogen, body condition score, or live weight. The cost of BLY silage was 8% less than BKO silage. T1 had the higher margin over cost of feeds followed by T2. Both silages alone or in combination are viable options for SSDS, as there were no differences in performance, or in feeding costs or margins.

Kikuyu pastures associated with tall fescue grazed in autumn in small-scale dairy systems in the highlands of Mexico

Intensive grazing increases the profitability and sustainability of small-scale dairy systems by reducing feeding costs. Kikuyu grass is a subtropical species from East Africa that has similar performance compared with temperate grasses when grazed by dairy cows in these systems during the summer rainy season but reduces growth and quality at low temperatures, when temperate species may have an advantage. The objective was to evaluate intensive grazing of kikuyu pastures (KYKY) alone or in association with two varieties of endophyte-free tall fescue, TF-33 (TF33) and Cajun II (CAJN), during the summer-autumn transition period when low temperatures set in, by lactating cows in small-scale dairy farms. Pasture variables were analysed with a split-plot design for sward height, net herbage accumulation and chemical composition, in vitro digestibility of organic matter, and estimated metabolisable energy content of herbage and concentrate. Experimental design for animal variables was a 3 × 3 Latin Square repeated three times with nine Holstein cows and 14 days experimental periods. Cows received 4.65 kg DM/day of a 16% CP commercial concentrate. Milk yield and composition, live weight, and body condition score were recorded. There were no significant differences (P > 0.05) for sward height and net herbage accumulation, nor for important components of chemical composition of herbages. There were no significant differences (P > 0.05) for milk yield (19 kg/cow/day) and composition, although differences (P < 0.05) were detected for live weight and body condition score. The conclusion is that there is no advantage of associating tall fescue with kikuyu in summer-autumn transition period for small-scale dairy systems.

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.

Nitrogen utilisation efficiency in small-scale dairy systems in the highlands of Central Mexico

Nitrogen (N) plays an important role in small-scale dairy systems, both in production costs and as an indicator of environmental impact. The objective of this study was to quantify nitrogen inputs and outputs to identify areas for improvement in nitrogen utilisation efficiency (NUE). Evaluation was in 12 small-scale dairy farms with different feeding strategies. Six followed the traditional cut and carry of irrigated temperate pastures (CUT), and six have implemented grazing of pastures (GRZ), quantifying N inputs and outputs from May 2016 to April 2017. Data were analysed by ANOVA following a split-plot model with season (rainy or dry) as main plots and feeding strategy (CUT or GRZ) as split-plots, with results in kilograms N per hectare and kilograms N per cow. There were differences (P < 0.05) between seasons and strategies in N inputs from purchased N fertilisers and purchased feeds as concentrates and roughages, showing different N inputs and outputs whether in CUT or GRZ strategies. There were also significant interactions between seasons and strategies as in the sale of animals, where GRZ sell throughout the year, while CUT sell at the beginning of the dry season. N balance ranged from 33.9 to 183.0 kg N/ha, and 37.8 to 111.0 as kilograms N per cow with an interaction (P < 0.05) between season and strategies. There was a larger N surplus in GRZ during the rainy season from fertiliser inputs, which reduced N utilisation efficiency (NUE). Mean NUE in kilograms N per hectare and kilograms N per cow was 19%, with the higher efficiency for GRZ in the dry season. Farms with the best NUE had lower use of fertilisers and purchased feeds.

Milk production and fatty acid profile of dairy cows grazing four grass species pastures during the rainy season in small-scale dairy systems in the highlands of Mexico

The study evaluated small-scale dairy systems with continuous grazing of pastures based on three temperate grasses festulolium (FL), tall fescue (TF), and perennial ryegrass (RG), compared with subtropical kikuyu grass (KG). All pastures were associated with white clover (Trifolium repens L.). Twelve multiparous Holstein cows were assigned to a 4 × 4 Latin square replicated three times with 14-day experimental periods. Sampling and analyses of pastures, concentrates, and animal variables followed standard procedures. FL showed a significantly (p < 0.05) higher mean sward height, but there were no differences (p > 0.05) in net herbage accumulation. There were significant differences (p < 0.05) among pastures for CP, NDF, ADF, in vitro digestibility of OM (IVOMD), and estimated metabolizable energy (eME). There were no differences (p > 0.05) between treatments for milk yield and composition, live weight, or body condition score. There were significant differences (p < 0.05) in fatty acid values for pastures in C14:0, C16:1, and C18:3n3. There were significant differences between treatments (p < 0.05) in milk contents for C18:0, C18:1t11, and C18:2c9t11. Grazing FL, TF, RG, or KY pastures showed no differences in milk yields. Higher values for C18:0, C18:1t11, and C18:2c9t11 were detected in KY, RG, and TF. RG had significantly higher MUFA than FL and higher PUFA than TF. A value under 65% of SFA, a ratio of n-6/n-3 lower than 4, and an atherogenic index of 1.7 are indicators of milk with beneficial effects for human health.

Evaluation of comparative advantages in the profitability and competitiveness of the small-scale dairy system of Tulancingo Valley, Mexico

This article combines a Policy Analysis Matrix with a sensitivity and poverty line analysis with the objective of evaluating the economic contribution of comparative advantages to the private profitability and competitiveness of small-scale dairy systems. For 1 year, socioeconomic data were collected from 82 farms selected from four strata via statistical sampling. Two scenarios were established to determine the quantitative contribution of comparative advantages: (1) a simulated scenario, which accounted for the cost of purchasing the total food and the opportunity cost of the family labour force (FLF), and (2) an actual production scenario, which accounted for the cost of producing food and eliminating the payment of the FLF and included other income. The E3 and E4 producers were the most profitable and competitive in the simulated scenario and actual production scenario. Of the four scales evaluated, the E2 and E1 producers were the most efficient in taking advantage of the economic contribution provided by the comparative advantages in their own production of food and employment of the FLF, in addition to accounting for other income, a condition that increased their profitability by 171 and 144% and competitiveness by 346 and 273%, respectively. The poverty results indicated that only E3 and E4 producers were non-vulnerable in the simulated scenario and actual production scenario. The purchase of food was the comparative advantage with the greatest sensitivity to cost increases in the two scenarios analysed, which exacerbated the effect on the E1 and E2 producers.

Intensive grazing and maize silage to enhance the sustainability of small-scale dairy systems in the highlands of Mexico

The effects of two innovative feeding strategies-intensive grazing (GR) and maize silage (MS)-on the sustainability of small-scale dairy systems (SSDS) were assessed in the highlands of central Mexico. On a total of 24 farms, four innovations were adopted between 2011 and 2014. Five farms continued their conventional feeding strategy (CC) of cut-and-carry pasture supplemented with commercial concentrate and ground corn grain, as well as straws (maize, oat, and wheat) in the dry season of feed scarcity; six farms implemented MS in the dry season; six farms GR of pastures; and seven farms implemented both GR and MS. Assessment in 2015 showed that farms which implemented both GR and MS had a higher local diversity score (P ≤ 0.001), higher scores for ethics and human development, and a higher score in economic independence (P ≤ 0.05) than farms that implemented only one of the innovations. The overall sustainability score (with range 0-100) was 46 for CC, 47 for MS, 52 for GR, and 55 for GR + MS. The innovations reduced feeding costs and enhanced sustainability, particularly when GR + MS were both implemented.

Effect of stocking rate and supplementation on performance of dairy cows grazing native grassland in small-scale systems in the highlands of central Mexico

The use and management of native grassland for dairy production during the rainy season was studied on two small-scale dairy farms in the highlands of central Mexico. Two stocking rates (2 and 4 cows/ha) and two levels of supplementation with commercial concentrate (4 and 6 kg/cow/day) under grazing were given to 12 milking Holstein cows in a 4 × 4 Latin square design replicated three times in a factorial arrangement. Net herbage accumulation (NHA), sward height, chemical composition, and in vitro digestibility of organic matter were recorded for the grassland, as well as vegetation cover and herbage mass 12 weeks post experiment. Animal performance variables were milk yield and composition, live weight, and body condition score. A partial budget analysis of feeding costs, returns, and margins was calculated. There were no differences between periods for NHA and herbage height and between plots for chemical composition (P > 0.05). However, there were highly significant differences among periods (P < 0.01) for organic matter, neutral detergent fibre (NDF), acid detergent fibre, in vitro organic matter digestibility (IVOMD), and estimated metabolisable energy (eME), with highly significant plot × period interactions (P < 0.01) for NDF, IVOMD, and eME. There were no statistical differences (P > 0.05) between treatments for milk yield, chemical composition of milk, live weight, or body condition score. Post-experimental vegetation cover was 72 % for both stocking rates, indicating there was no degradation of the grassland. Lower feeding costs were for the low supplementation treatments. It is concluded that a high stocking rate in studied native grasslands of 4 cows/ha with moderate concentrate supplementation supports a mean milk yield of 11.9 kg/cow/day during the rainy season without deleterious effects on the grassland.