Grass Dry Matter Research Articles

Nitrogen and potassium supply and the morphogenic and productive characteristics of marandu palisadegrass

The objective of this work was to study morphogenic characteristics, and dry matter production of roots and shoots of marandu palisadegrass (Brachiaria brizantha cv. Marandu) submitted to combinations of nitrogen and potassium, in a nutritive solution, employing silica as substrate. The experiment was carried out in a greenhouse during the summer. It was used a 5² fractionated factorial scheme with 13 combinations of nitrogen and potassium, which were distributed in a randomized block design, with four replications. The nitrogen × potassium interaction was significant for the number of tillers and leaves, for leaf area, for shoots and root section dry mass, for total length and surface and specific length and surface in the roots. Production of aerial part dry mass positively correlated with the number of tillers and leaves and grass leaf area. Nitrogen rates modulated the root system development, and the root specific length and surface decreased when high rates of nitrogen and potassium were supllied. Nitrogen and potassium influence Marandu palisadegrass morphogenic characteristics, which are determinant for grass dry matter production.

Comparative grazing behavior of lactating Holstein-Friesian, Jersey, and Jersey × Holstein-Friesian dairy cows and its association with intake capacity and production efficiency

The objectives of this study were to investigate differences in grazing behavior among Holstein-Friesian (HF), Jersey (JE), and Jersey × Holstein-Friesian (F1) cows under an intensive, seasonal, grass-based environment and to determine whether associations exist among grazing behavior, intake capacity, and production efficiency. Data from a total of 108 animals (37 HF, 34 JE, and 37F1) were available for analysis. Measurements included milk production, body weight (BW), intake, and grazing behavior. Breed group had a significant effect on all of the production, grass dry matter intake, and efficiency parameters investigated. No differences were observed among the breeds for grazing time, number of grazing bouts, grazing bout duration, and total number of bites. Grazing mastications were higher for the JE cows compared with the HF cows. Grass dry matter intake per bite and rate of intake per minute were higher for the HF cows compared with the JE cows. Large differences between the breeds were apparent when grazing behavior measurements were expressed per unit of BW and per unit of intake. In absolute terms, the HF cows spent more time ruminating and had more mastications during rumination than the JE cows. However, when expressed per unit of BW, ruminating time was greater for the JE cows and they tended to have more ruminating mastications compared with the HF cows. Despite these differences, ruminating time and ruminating mastications per unit of intake were similar for the 2 breeds. For the most part, the F1 cows tended to be similar to the mid-parent mean, but results showed an increase in biting rate, lower grazing duration per bout, and a tendency to achieve a high intake per bite compared with the average of the parent breeds. The results obtained also indicate that inherent grazing and ruminating differences exist between cows varying in intake capacity and production efficiency. Cows with higher intake capacities have increased grazing time and rate of intake per unit of BW. Increased production efficiency, on the other hand, appears to be aided, in particular by improvements in mastication behavior during grazing.

Influência de distintas lâminas de irrigação no desenvolvimento e na qualidade visual da grama-batatais

Green areas have been expanding in cities with the proliferation of green areas at many sites (residential condominium gardens, soccer fields, golf courses etc.). Unfortunately, the water resources are limited and are not enough to attend all users simultaneously. Therefore, the rational use of water becomes necessary, mainly for irrigation purposes. This work had the main objective of evaluating the effect of water depths application, according to different reposition of the grass ( Paspalum notatum ) reference evapotranspiration (ETo) (40, 60, 80 and 100%), on grass dry matter production, aiming to obtain the minimum water depth necessary to maintain the visual quality of grass with water and energy savings. After each grass cutting, dry matter production was evaluated, allowing the determination of water use efficiency (WUE). Grass visual quality was evaluated by means of applying a questionnaire, using 16 evaluates. The models were chosen using the t-test, with level of probability up to 15% in the determination coefficient (R2). The results indicate that the dry matter production and the visual quality of the grass were not affected by the different water depths applied in the coldest months (July and August). A water depth of 40% ETo was recommended in July. For the other months, the water depth of 80% of ETo was recommended.

Stability of fatty acids in grass and maize silages after exposure to air during the feed out period

Lipids in forages are extensively hydrolysed in the silo with a concomitant increase in the level of free fatty acids (FFA). After opening of the silo, exposure of the FFA to air and light with, a concomitant increase in pH and microbial growth, could induce oxidization. The present study investigated the stability of FA in grass and maize silages exposed to air for 0, 12 and 24 h. Eight maize silages were selected with varying dry matter (DM) contents, being very wet, wet, normal and dry. In addition, eight grass silages were chosen on the basis of ammonia (NH 3) concentration and pH level. Grass and maize silages were sampled 8–10 weeks after ensiling and anaerobically transported to the lab in cooled plastic bags. After mixing, each sample was divided into three subsamples and exposed to air for 0, 12 or 24 h. Concentrations of individual FA were quantified by gas chromatography. Among the investigated silages, concentrations of total FA varied greatly and ranged from 16.4 to 23.9 and 9.5 to 21.6 g/kg DM in grass and maize silages, respectively. Exposure to air up to 24 h lowered ( P<0.01) the contents of linolenic acid (C18:3), linoleic acid (C18:2), oleic acid (C18:1) and total FA in maize silages. In grass silages, 24 h exposure to air decreased ( P<0.05) concentrations of C18:3, C18:2 and total FA ( P<0.01). In both grass and maize silages a decline in concentrations of major unsaturated FA (UFA) was associated with a concomitant increase ( P<0.01) in the proportion (g/g total FA) of palmitic acid (C16:0). The relative decrease in total FA after 24 h exposure to air was higher in maize silages with a high moisture content, and progressively decreased with increasing DM content. In contrast, pH and NH 3 levels of grass silages had no effect on the stability of FA during feed out. The present study demonstrates that extended exposure of silages to air during feeding increased the proportion (g/g total FA) of C16:0 and lowered the concentration of polyunsaturated FA.

Sward characteristics, grass dry matter intake and milk production performance are affected by pre-grazing herbage mass and pasture allowance

The objective of this study was to investigate the effect of pre-grazing herbage mass (HM) and pasture allowance (PA) on sward characteristics, milk production performance, dry matter intake (DMI) and rumen fermentation of spring calving dairy cows. Sixty-four Holstein–Friesian dairy cows (mean calving date, February 11) were balanced and randomly assigned to one of four treatments ( n = 16) in a 2 × 2 factorial design. Two swards, a low HM (L HM) sward (1600 kg dry matter (DM)/ha) and a high HM (H HM) sward (2400 kg DM/ha), were created by varying the regrowth interval before the study start date, with two PA, 15 and 20 kg DM/cow/day imposed on each sward. Animals fitted with rumen cannula ( n = 4) moved in a complete Latin square to investigate the effect of HM and PA on rumen fermentation. The study lasted 30 weeks and was analysed as two periods; PI (April 9–July 20) and PII (July 21–October 31). Sward structural characteristics, grass dry matter intake (GDMI) and rumen fermentation were investigated during PI and PII. The mean HM was 1551 kg DM/ha and 2678 kg DM/ha for L HM and H HM respectively in PI, and 1753 kg DM/ha and 2281 kg DM/ha for the L HM and H HM respectively in PII. During PII, the leaf proportion (> and <40 mm) was higher in the L HM swards than the H HM swards. There was a lower dead proportion > 40 mm in the L HM swards compared to the H HM swards. In PI, the L HM treatments had significantly higher milk production (+ 0.9 kg), milk protein yield (+ 42.4 g/day) and milk lactose yield (+ 42.9 g/day). Increasing PA increased milk yield (+ 1.1 kg; + 1.8 kg), solids-corrected milk (+ 0.9 kg; + 1.3 kg), protein (+ 67.9 g/day; + 63.5 g/day) and lactose (+ 55.2 g/day; + 80.1 g/day) yield in PI and PII respectively. The milk response per kilogram of GDMI was 1.13 kg for the L HM animals compared to 0.65 kg for the H HM animals. Rumen pH was lower for animals grazing the L HM swards (pH 5.69) than for animals grazing the H HM swards (pH 5.88) with no adverse rumen conditions evident. The results of this study suggest that L HM (1600 kg DM/ha) and 20 kg PA had a positive effect on sward characteristics which resulted in increased milk production and sward quality.

Teores de proteína para vacas lactantes em pastejo de capim-elefante

Avaliou-se o efeito da utilização de concentrados com diferentes teores de proteína bruta (PB) para vacas em lactação sob pastejo rotacionado de capim-elefante, distribuídas em três quadrados latinos (3x3). Os tratamentos foram concentrados suplementares contendo 15,2; 18,2 ou 21,1% de PB. Foram oferecidos 3kg de concentrado por vaca, duas vezes ao dia. A disponibilidade de matéria seca (MS)/ha de capim-elefante foi de 1.873kg ou de 17,4kg de MS/vaca dia-1. A MS do capim-elefante foi de 19,6%, contendo 13,9% de PB e 66,1% de fibra detergente neutro (FDN) e 67,4% de digestibilidade in vitro da MS (DIVMS). Não houve diferença (P&gt;0,05) entre os tratamentos quanto ao consumo diário de MS da dieta total (21,5; 21,6 e 20,8kg/d), MS do capim-elefante (16,1; 16,3 e 15,5kg/d) e FDN do capim-elefante (10,7; 10,7 e 10,3kg/d). As produções de leite (17,5; 17,2 e 17,6kg/d) e os teores de gordura (3,4; 3,5 e 3,5%), proteína (2,9; 2,9 e 2,9%), lactose (4,4; 4,4 e 4,4%) e N-ureia no leite (14,1; 14,6 e 15,8mg/dL) não diferiram (P&gt;0,05) entre os tratamentos (respectivamente, para 15,2; 18,2 ou 21,1% de PB). O teor de N-ureia no plasma foi maior (P&lt;0,05) em vacas alimentadas com concentrado com 21,1% de PB (na ordem citada: 11,5; 12,2 e 14,4mg/dL). Nas condições experimentais, o concentrado suplementar com 15,2% de PB pode ser utilizado na alimentação de vacas em lactação em pastagem de capim-elefante.

Determination of Dry Matter Yield from Legume–Grass Swards by Field Spectroscopy

ABSTRACTAn efficient and accurate detection of dry matter (DM) yield of legume–grass mixtures can facilitate a targeted and site‐specific management of legume‐based swards. The major objective of this study was to examine the relationship between spectral signatures of legume–grass swards and DM yield across a wide range of legume species (white clover [Trifolium repens L.], red clover [T. pratense L.], alfalfa [Medicago sativa L.], birdsfoot trefoil [Lotus corniculatus L.]), legume proportion (0–100% of DM), and growth stage (beginning of tillering to end of flowering). Modified partial least squares (MPLS) regression, stepwise multiple linear regression (SMLR), and the vegetation indices (VIs), simple ratio, normalized difference vegetation index, enhanced vegetation index, and red edge position were used for analysis of the hyperspectral data set (350–2500 nm). Compared to common calibrations, legume‐specific models achieved better results, indicating that each legume species had its own spectral characteristics. Modified partial least squares and SMLR gave the best R2 values, ranging in cross validation from 0.74 to 0.92 with a standard error below 92 g DM m−2 The DM yield prediction by VIs resulted in unsatisfactory accuracies. Prediction accuracy for MPLS and SMLR models were still acceptable even with a reduced spectral data set (630–1000 nm), a finding that could facilitate an application of field spectroscopy in practice.

Effect of three forages and two forage allowances offered to pregnant dry dairy cows in winter on periparturient performance and milk yield in early lactation

AbstractSixty multiparous, Holstein–Friesian pregnant dry dairy cows were allocated to three forage treatments (n = 20; fodder beet, kale or grass silage) at two feeding allowances (n = 30; high and low) for 70 (s.e. of mean, 16) d before parturition. Cows offered the high feeding allowance were offered 9 kg of dry matter (DM) of kale or fodder beet grazed in situ plus 5 kg DM of baled grass silage daily or clamp grass silage ad libitum offered indoors. Cows offered the low feeding allowance were offered 6 kg DM of kale or fodder beet grazed in situ plus 3·5 kg DM baled grass silage daily, or 9·5 kg DM of clamp grass silage daily offered indoors. After calving, all cows received a daily allowance of 14 kg DM perennial ryegrass herbage at pasture plus 4 kg concentrate cow−1 for the first 35 d of lactation. Cows offered grass silage had a greater increase in body condition score pre‐partum compared to those offered kale or fodder beet. Cows offered fodder beet pre‐partum had a greater milk solid and solids‐corrected milk yield in the first 35 d of lactation than those offered kale and grass silage pre‐partum. Offering fodder beet and kale pre‐partum increased plasma non‐esterified fatty acid concentrations pre‐partum relative to offering grass silage. Offering kale pre‐partum resulted in higher insulin‐like growth factor‐1 concentration post‐partum but lower plasma copper concentration pre‐partum and at calving than kale or grass silage. Offering the higher forage allowance pre‐partum resulted in a higher plasma calcium concentration at calving and higher plasma non‐esterified fatty acid concentration post‐partum.

Recria de bezerras de corte em alternativas de uso da pastagem de azevém

Avaliou-se o desempenho de bezerras de corte dos 8 aos 12 meses de idade em pastagem exclusiva de azevém (Lolium multiflorum Lam.) ou em pastagem de azevém em consórcio com trevo-vermelho (Trifolium pratense) LE 116 ou azevém com suplemento (1% do peso vivo (PV) por dia). O método de pastejo foi o de lotação contínua com número variável de animais. O suplemento utilizado foi ração comercial, com 17% de proteína bruta, 23,6% de fibra em detergente neutro e 59,6% de nutrientes digestíveis totais. Os valores médios de massa e oferta de forragem e oferta de lâminas foliares foram de 1.327,2 kg/ha de MS, 10,5 e 3,7 kg de MS/100 kg de PV, respectivamente. O ganho de peso médio diário foi semelhante entre as bezerras em pastagem de azevém com suplemento e aquelas em pastagem de azevém mais trevo-vermelho, com valor médio de 1.039 gramas. A carga animal e o ganho de peso vivo por área foram maiores quando animais receberam suplemento. A suplementação proporcionou efeito aditivo no consumo total de matéria seca e substitutivo no consumo de matéria seca do pasto.

Comportamento produtivo e características nutricionais do capim-braquiária cultivado em consórcio com milho

Com o objetivo de estudar o comportamento produtivo do consórcio capim-braquiária e milho, foram avaliadas as características bromatológicas da planta inteira e das frações folha e colmo do capim-braquiária produzido de diferentes arranjos de semeadura. Avaliaram-se as produções de matéria seca (MS), proteína bruta (PB) e nutrientes digestíveis totais (NDT) por área e os teores de PB, proteína bruta digestível (PBD), proteína insolúvel em detergente neutro (PIDN), fibra em detergente neutro (FDN), lignina (LIG) carboidratos não-fibrosos (CNF) e NDT na MS da forrageira e a relação folha:colmo (F:C) em diferentes arranjos de semeadura e idades das culturas. Os arranjos de semeadura testados foram: duas fileiras do capim-braquiária nas entrelinhas do milho; semeadura a lanço do capim-braquiária nas entrelinhas do milho; uma fileira do capim-braquiária na mesma fileira do milho; uma fileira do capim-braquiária nas entrelinhas do milho; capim-braquiária em cultivo exclusivo e milho em cultivo exclusivo. O efeito da idade das culturas foi avaliado em amostras de plantas colhidas aos 128, 141, 174 e 199 dias após o plantio. As maiores produções de MS, PBD e de NDT por hectare foram obtidas com o capim-braquiária em cultivo exclusivo. Durante o período em que o sombreamento da cultura do milho sobre o dossel do capim-braquiária foi mais intenso, a relação folha:colmo do capim-braquiária em consórcio foi menor que a do capim cultivado na forma exclusiva. As forrageiras oriundas dos arranjos com maior sombreamento (capim-braquiária semeado a lanço nas entrelinhas do milho e uma fileira de capim-braquiária na mesma fileira do milho) foram menos produtivas e apresentaram maiores teores de PB na MS. Em média, a fração folha apresentou maiores teores de PB e menores teores de FDN e lignina em comparação à fração colmo, independentemente do arranjo de semeadura. O consórcio capim-braquiária e milho não influenciou os teores de lignina, carboidratos não-fibrosos e nutrientes digestíveis totais na matéria seca do capim-braquiária, no entanto, a idade teve efeito sobre essas variáveis. A produtividade do milho não foi afetada pelo consórcio em nenhum dos arranjos.

Feed intake, digestibility and body weight gain of sheep fed Napier grass mixed with different levels of S esbania sesban

A randomized complete block design was employed to assess the feed intake, nutrient digestibility and live weight gains of hair type local sheep (~ 18.0 kg initial live weight) fed Napier grass ( Pennisetum purpureum) mixed with different levels of Sesbania ( Sesbania sesban). The treatments were sole Napier grass (control) and four Napier grass- Sesbania mixtures consisting of 100, 200, 300, and 400 g/kg of Sesbania on dry matter (DM) basis. The ratio of mixing the two feeds was adjusted every week based on DM content of each feed component to maintain a constant ratio on DM basis. The DM, ash, crude protein (CP) and acid detergent lignin (ADL) contents of the Napier grass- Sesbania mixtures increased as the proportion of Sesbania increased and the reverse was true for organic matter (OM), neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents. The DM intake was higher ( P < 0.05) in the mixed diets than in the sole Napier grass diet while the OM intake was higher ( P < 0.05) in the diet containing 400 g/kg of Sesbania (52.9 g kg W − 0.75 day − 1 ) than Napier grass alone (47.5 g kg W − 0.75 day − 1 ). Crude protein intake increased with increased inclusion level of Sesbania in the diet. Dry matter and OM digestibilities were higher ( P < 0.05) in the mixed diets containing 200, 300 and 400 g/kg Sesbania than Napier grass alone. Crude protein digestibility was significantly higher ( P < 0.05) in all the mixed diets than sole Napier grass diet whereas NDF digestibility was higher in the mixed diet containing 400 g/kg Sesbania than sole Napier grass diet. The sheep that were fed the diet containing 300 g/kg Sesbania foliage showed significantly higher ( P < 0.01) average daily body weight gain (103 g/day) than the unsupplemented control group (75.6 g/day). In general, all the experimental sheep showed good growth performances throughout the experimental period.

Effects of maturity stage and feeding strategy of whole crop barley silage on intake, digestibility and milk production in dairy cows

Five diets containing concentrate, grass silage and whole crop barley silage (WCBS) harvested at different maturity stages were fed to 15 multiparous dairy cows in an incomplete change-over design over three periods. Three diets contained 10.7 kg dry matter (DM) concentrate, 4 kg DM grass silage, and ad libitum access to WCBS harvested at either the heading stage (B1), the early milk stage (B2) or the early dough stage (B3) of maturity. The other two diets contained 10.7 kg DM concentrate, whereas grass silage and WCBS at heading were mixed at two different ratios with a DM content of WCBS of either 0.30 (M1) or 0.70 (M2), and the mixtures were fed ad libitum. Intakes of DM (kg day − 1 : B1 = 21.0, B2 = 20.6 and B3 = 20.0) and neutral detergent fibre (NDF; kg day − 1 : B1 = 7.0, B2 = 6.4 and B3 = 6.3) decreased, whereas starch intake increased (kg day − 1 : B1 = 3.1, B2 = 3.5 and B3 = 4.0) with increasing maturity at harvest. The apparent organic matter (OM) digestibility (g kg − 1 : B1 = 800, B2 = 774 and B3 = 729) decreased with increasing maturity stage, and consequently so did the digestible OM intake. Milk (kg day − 1 : B1 = 27.2, B2 = 26.1 and B3 = 25.9) and energy corrected milk (ECM; kg day − 1 : B1 = 31.0, B2 = 29.4 and B3 = 28.2) yields, and protein concentration (g kg − 1 : B1 = 37.1, B2 = 36.4 and B3 = 36.0) decreased with increasing maturity stage of the WCBS. When cows were fed diet B3 the milk fat concentration decreased (46.4 g kg − 1 ) compared to diets B1 (49.3 g kg − 1 ) and B2 (49.4 g kg − 1 ). The difference in ECM yield between diets B1 and B3 was due to a combined effect of lower milk yield, and lower protein and fat concentrations. This was caused by the higher starch and lower NDF intakes with diet B3, which decreased the milk fat concentration. Moreover, a lower energy intake of diet B3 due to lower OM digestibility decreased milk protein concentration and milk yield. Mixing WCBS at the heading stage with grass silage (M2) decreased digestibility, compared to feeding the forages separately (B1). However, the differences were small and may be a result of soil contamination at harvest of some of the silages, which made the method with using incomplete faecal collection and internal marker acid insoluble ash less reliable. Including WCBS at the heading stage at 0.30 or 0.70 of forage DM did not affect DM intake or diet digestibility, probably because the grass silage in the study was very similar in energy content to the WCBS harvested at heading.

Effect of herbage allowance and concentrate supplementation on dry matter intake, milk production and energy balance of early lactating dairy cows

The objective of this study was to investigate the effect of daily herbage allowance and concentrate supplementation level offered at approximately 40 and 80 days in milk (DIM) and the carryover effects at 120 DIM on the production performance of spring calving dairy cows. Sixty-six (30 primiparous and 36 multiparous) Holstein–Friesian dairy cows (mean calving date — 7 Feb ± 9.9 days) were randomly assigned to a 6 treatment ( n = 11) grazing study. The experiment was a randomised block design with a 3 × 2 factorial arrangement of treatments (3 daily herbage allowances (DHA's; approximately 13, 16 and 19 kg DM/cow/day; > 4 cm) and 2 concentrate allowances (0 and 4 kg DM/day). Treatments were imposed from 21 February to 8 May. Following this period (subsequent 4-weeks) animals were offered a daily herbage allowance of 20 kg DM/cow/day and no concentrate. Milk production, total dry matter intake (TDMI), energy balance (EB) and blood metabolites were measured on three occasions — at approximately 40, 80 and 120 days in milk, R1, R2 and the carryover period, respectively. Cows offered a low DHA had a lower post-grazing sward height but increased sward utilisation (> 4 cm) during R1 and R2, there was no difference during the carryover period. Concentrate supplementation increased post-grazing sward height by 11% during R2 but had no effect during R1 and the carryover period. Daily herbage allowance had no effect on milk yield or composition during R1 however a low DHA tended to reduce milk yield in R2. Concentrate supplementation increased milk and solids corrected milk (SCM) yield by 4.1 and 2.8 kg/cow/day, respectively during R1 and also increased R2 milk production performance, this effect extended into the carryover period. Offering a low DHA restricted grass dry matter intake (DMI) during R1 and R2 yet concentrate supplementation significantly increased total DMI (2.3 (R1) and 3.0 (R2) kg DM/cow). Animals offered a low DHA had a significantly lower bodyweight (BW) than those offered a medium or high DHA during P1 and P2. Concentrate supplementation increased BW during P1 and P2 (+ 9 and + 14 kg/cow, respectively). There was no effect of treatment on BW during P3. There was no effect of DHA on EB in R1; during R2 animals offered a low DHA had the lowest EB. Concentrate significantly increased EB in R1 and R2 and increased plasma glucose concentration while it decreased plasma NEFA and BHB concentrations. The results of this study indicate that animals should be offered a low DHA up to 80 DIM after which DHA should be increased however animals should also be supplemented with concentrate during the early post-partum period.

The Effect of Herbage Allowance and Concentrate Supplementation on Milk Production Performance and Dry Matter Intake of Spring-Calving Dairy Cows in Early Lactation

The objective of this study was to determine the effect of daily herbage allowance (DHA) and concentrate level on milk production and dry matter intake of spring-calving dairy cows in early lactation. Seventy-two Holstein-Friesian dairy cows (mean calving date February 2) were randomly assigned across 6 treatments (n = 12) in a 2×3 factorial arrangement. The 6 treatments consisted of 2 DHA (>4cm) and 3 concentrate levels: 13kg of herbage dry matter/cow per d (low) or 17kg of herbage dry matter/cow per d (high) DHA and unsupplemented, 3kg, or 6kg of dry matter concentrate/cow per d. The experimental period (period I) lasted 77 d and was followed by a carryover period (period II) during which animals were randomly reassigned across 2 grazing treatments offering 17 or 21kg of herbage dry matter/cow per d. Increasing DHA significantly increased milk (+1.85kg), solids-corrected milk, protein (+79.5g), and lactose yields, protein concentration, and mean body weight (BW). Mean body condition score (BCS) and end-point BCS were also significantly higher with the high-DHA treatments. There was a linear response in milk yield, milk lactose concentration, and solids-corrected milk to concentrate supplementation. There was a significant difference in mean BW as concentrate increased from 0 to 3kg (506 and 524kg, respectively); there was no further increase in BW when 6kg of concentrate was offered. Cows offered the low DHA had significantly lower grass dry matter intake (13.3kg) and total dry matter intake (16.3kg) than the high-DHA cows during period I. Concentrate supplementation significantly increased total dry matter intake. During period II, previous DHA continued to have a significant carryover effect on milk protein concentration, BW change, mean BCS, and end-point BCS. Concentrate supplementation during period I continued to have a significant carryover effect in period II on milk yield; milk fat, protein, and lactose yields; solids-corrected milk yield; BW; and mean BCS. Results from this study indicate that offering a medium level of DHA (17kg of herbage dry matter) in early lactation will increase milk production. Offering concentrate will result in a linear increase in milk production. In an early spring feed-budgeting scenario, when grass supply is in deficit, offering 3kg of dry matter concentrate with 17kg of DHA has the additive effect of maintaining the grazing rotation at the target length as well as ensuring the herd is adequately fed.

Diferentes métodos de controle de plantas indesejáveis em pastagem nativa

O experimento foi desenvolvido em área de pastagem nativa representativa da transição entre a Serra do Sudeste e a Depressão Central do Rio Grande do Sul, onde as espécies indesejáveis foram representadas especialmente por carqueja (Baccharis trimera (Less.) DC.), caraguatá (Eryngium horridum (Spreng.) Less.) e alecrim (Vernonia nudiflora Less.). Foram avaliados os efeitos iniciais de dois métodos de controle de espécies indesejáveis (até 60 dias após aplicação) sobre a produção de forragem, a dinâmica da vegetação e a eficiência de controle: sem-controle; controle mecânico; e controle químico (herbicida comercial à base de Picloram [64 g/L] + 2,4-D [240 g/L], na dosagem de 5 L do produto comercial/ha). Os tratamentos foram arranjados em um delineamento em blocos ao acaso, com quatro repetições. A massa gramíneas verdes secas e a massa total de MS não diferiram entre os métodos de controle. Foram obtidos valores de 587,9; 472,0 e 0 kg de MS com o controle mecânico, o controle químico e sem-controle, respectivamente, o que comprova influência do método de controle sobre a massa de forragem de leguminosas. A eficiência de controle das espécies indesejáveis, em comparação à ausência de controle, foi de 76,2% para o controle químico e 27,9% para o controle mecânico. A eficiência de controle de espécies, sob aspectos de freqüência dos componentes da pastagem, evidenciou que o controle mecânico não foi eficiente aos 60 dias após aplicação no controle de plantas de alecrim no segundo toque (-27,7%) e plantas de caraguatá no primeiro toque (-30,0%).

Genetics of Grass Dry Matter Intake, Energy Balance, and Digestibility in Grazing Irish Dairy Cows

The objective of this study was to estimate genetic parameters for grass dry matter intake (DMI), energy balance (EB), and cow internal digestibility (IDG) in grazing Holstein-Friesian dairy cows. Grass DMI was estimated up to 4 times per lactation on 1,588 lactations from 755 cows on 2 research farms in southern Ireland. Simultaneously measured milk production and BW records were used to calculate EB. Cow IDG, measured as the ratio of feed and fecal concentrations of the natural odd carbon-chain n-alkane pentatriacontane, was available on 583 lactations from 238 cows. Random regression and multitrait animal models were used to estimate residual, additive genetic and permanent environmental (co)variances across lactations. Results were similar for both models. Heritability for DMI, EB, and IDG across lactation varied from 0.10 [8 days in milk (DIM)] to 0.30 (169 DIM), from 0.06 (29 DIM) to 0.29 (305 DIM), and from 0.08 (50 DIM) to 0.45 (305 DIM), respectively, when estimated using the random regression model. Genetic correlations within each trait tended to decrease as the interval between periods compared increased for DMI and EB, whereas the correlations with IDG in early lactation were weakest when measured midlactation. The lowest correlation between any 2 periods was 0.10, −0.36, and −0.04 for DMI, EB, and IDG, respectively, suggesting the effect of different genes at different stages of lactations. Eigenvalues and associated eigenfunctions of the additive genetic covariance matrix revealed considerable genetic variation among animals in the shape of the lactation profiles for DMI, EB, and IDG. Genetic parameters presented are the first estimates from dairy cows fed predominantly grazed grass and imply that genetic improvement in DMI, EB, and IDG in Holstein-Friesian cows fed predominantly grazed grass is possible.

Growth of vetivergrass for cutslope landscaping: Effects of container size and watering rate

A slope greening technique using vetivergrass has been adopted in Hong Kong on shotcreted surfaces. Vetiveria zizanioides (L.) Nash is the most commonly used species. Soil packed PVC tubes of 250 mm long and 150 mm in diameter are installed on slopes to form planters for vetivergrass growth. However, there is a paucity of information on the optimal tube size for grass growth. Together with soil characteristics, tube size determines water and nutrient availability and the space for growth. This study aimed to assess the suitability of containers of different height and diameter, and the effects of different watering rates on the growth of vetivergrass in a greenhouse experiment. Seven container dimensions and three watering rates were evaluated, and the growth of vetivergrass was measured every three months in terms of aboveground biomass for a year, while underground biomass was determined at the end of the experiment. In general, increasing water supply, diameter and height supported a denser cover of vetivergrass for the purposes of erosion control and decorating hard surface of cutslopes. Vetivergrass grew better when watered at rates equivalent to 1× and 2× the amount of annual precipitation than that at 0.5×, but the effect of watering diminished with decreasing diameter and height. Grass dry matter production increased with the diameter and, to a lesser extent, height of the PVC tubes. If watering is not possible, i.e. under 0.5× or 1× watering rate, a PVC tube with 250 mm height and 150 mm diameter seems to be the most suitable container. On the other hand, if irrigation is feasible, a smaller container can be used without detrimental effect on grass growth.

Sward characteristics, grass dry matter intake and milk production performance is affected by timing of spring grazing and subsequent stocking rate

The objective of this study is to investigate the effect of contrasting spring grazing dates (GD) and stocking rate (SR) on sward characteristics, grass dry matter intake and milk production performance of autumn calving dairy cows during the spring period. Two swards were created by grazing in March (early grazing; E) or by delaying first grazing until mid-April (late grazing; L). Two stocking rates, high (H; 5.5) and medium (M; 4.5) were applied across each sward. Forty eight autumn calving Holstein cows (160±35 days in milk) were assigned to one of four (n=12) different grazing treatments. The experiment began on April 17th and finished after 2 grazing rotations on June 20th. Later spring grazing significantly increased herbage mass (kg DM/ha) above ground level (+933, P<0.05) and >50 mm (+738, P<0.05). Compressed sward height (+22.1 mm, P<0.05), extended tiller height (+73 mm, P<0.001) and pseudostem height (+35 mm, P<0.001) were also significantly higher for later grazed swards. In the grazing horizon (>80 mm— extended tiller height), later grazed swards had significantly lower leaf proportion (−0.09, P<0.05) and higher dead material (+0.05, P<0.001). Daily herbage allowance (>50 mm) was on average 12.7, 15.9, 18.2 and 21.9 kg DM/cow for EH, EM, LH and LM, respectively. Daily leaf allowance (>80 mm) was 10.1, 12.3, 13.3 and 14.5 kg DM/cow for EH, EM, LH and LM, respectively. The EM (16.2 kg DM/cow), LH (+0.1 kg) and LM (0.8 kg) treatments all had similar grass DM intake, however there was evidence of an interaction (P<0.10) between GD and SR, this was due to the low grass DM intake of the EH (13.9 kg DM/cow) treatment. When expressed as UFL (Fill unit) intake the EM treatment recorded the highest value. There was a significant interaction between GD and SR (P<0.01) for milk, protein yield, 4% fat corrected milk yield (P<0.05) and protein concentration (P<0.001). Cows grazing the EM treatment produced 23.9 kg of milk, 876 and 685 g of fat and protein yield. The difference in milk production (cow/day) between EM and EH treatments was +3.6 kg milk, +98 g fat and +107 g protein. The production yield difference between LM and LH treatments was +1.1 kg milk, +27 g fat and +29 g protein in favour of the LM treatment (23.9 kg of milk, 877 and 687 g fat and protein yield). Herbage quality and morphological characteristics are clearly improved with early spring grazing as herbage mass is reduced on subsequent rotations. Swards grazed in early spring allow higher grass utilisation and high milk production performance when grazed at a medium stocking rate. Improved milk production from herbage can be achieved provided herbage mass and allowance are maintained at levels where herbage quality decreases are minimised.

The effects of offering a range of forage and concentrate supplements on milk production and dry matter intake of grazing dairy cows

AbstractAn experiment was undertaken to examine the effect of supplement type on herbage intake, total dry matter (DM) intake, animal performance and nitrogen utilization with grazing dairy cows. Twenty‐four spring‐calving dairy cows were allocated to one of six treatments in a partially balanced changeover design with five periods of four weeks. The six treatments were no supplement (NONE), or supplementation with either grass silage (GS), whole‐crop wheat silage (WS), maize silage (MS), rapidly degradable concentrate (RC) or slowly degradable concentrate (SC). Cows were rotationally grazed with a mean herbage allowance of 20·5 kg DM per cow per day, measured above 4 cm. Forage supplements were offered for approximately 2 h immediately after each morning milking, with cows on NONE, RC and SC treatments returning to the grazing paddock immediately after milking. Cows on treatment MS had a significantly higher supplement DM intake than the other treatments but a significantly lower grass DM intake than the other treatments, resulting in no significant difference in total DM intake when compared with cows on treatments WS, RC and SC. Concentrate type had no significant effect on herbage intake, milk yield, milk composition or yield of milk components. The yield of milk fat and milk protein was significantly higher on treatments MS, RC and SC compared with treatments NONE, GS and WS. The results indicate that despite a relatively high substitution rate, maize silage can be a useful supplement for the grazing dairy cow.

Effect of Spring Grazing Date and Stocking Rate on Sward Characteristics and Dairy Cow Production During Midlactation

The objective of this study was to investigate the effect of initial spring grazing date and subsequent stocking rate on sward characteristics, grazing behavior, milk yield, and dry matter intake of spring-calving dairy cows during the main grazing season. Sixty-four spring-calving Holstein-Friesian dairy cows (58±9 d in milk) were balanced and randomly assigned to 1 of 4 grazing treatments (n = 16) between April 12, and July 3, 2004. Two swards, an early-grazed (E) sward and a late-grazed (L) sward had 2 stocking rates, high and medium, imposed across them. Cows grazing the E swards were stocked at 4.5 cows/ha (E4.5) and 5.5 cows/ha (E5.5), whereas cows grazing the L sward were stocked at 5.5 cows/ha (L5.5) and 6.4 cows/ha (L6.4). Sward characteristics, grazing behavior, and grass dry matter intake (GDMI) were investigated during the second (R2) and fourth grazing rotations (R4). Total dry matter yield was greater on L swards in R2. In R2, the E swards had a greater proportion of leaf as well as a lesser stem and dead dry matter yield. During R2, organic matter digestibility and crude protein content were greater on the E sward than the L sward. Pre-and postgrazing heights were greater for the L swards in R2 and R4. In R4, there was a larger leaf allowance on the E swards. Grazing time was greater and ruminating time lesser for animals grazing the E sward in R2. During R4, intake per bite was greater for the E5.5 and E4.5 treatments. Milk and solids-corrected milk yields as well as GDMI were greater for animals grazing the E sward in both R2 and R4. The results of the present study suggest that early grazing initially had a positive effect on sward quality and structure, which resulted in improved grazing behavior characteristics, increased GDMI, and increased milk production. During R4, sward quality and structure were similar between swards; thus, differences in grazing behavior were due to divergent daily herbage allowances. These results suggest that sward structure and quality as well as daily herbage allowance are important factors that influence animal performance and grazing behavior.