Ryegrass Pasture Research Articles

Forage Mineral Concentrations and Mineral Status of Beef Cattle Grazing Cool Season Pastures in Northwestern Florida, Emphasizing Magnesium

A 68‐day study was conducted in North Florida to evaluate forage and beef cattle serum, liver, and urine mineral concentrations, emphasizing magnesium (Mg). Forty‐two Angus, Brangus, and Romosinuano cows in early lactation were divided into two groups and placed on ryegrass or oat pasture. Samples were collected every 2 weeks except for liver biopsies, which were collected only on day 68. Mineral concentrations were determined for forage, plasma, urine, and liver samples. All forage mineral concentrations except Mg, calcium (Ca), copper (Cu), cobalt (Co), selenium (Se), and zinc (Zn) were greater than critical levels for a beef cow in lactation. Forage Mg and Cu were severely deficient in both oats and ryegrass. All blood plasma mineral levels were greater than critical levels, but plasma Mg was borderline to slightly deficient. There should be special attention given to Mg supplementation because forages are deficient and contain excess potassium (K).

Ingestive behavior and displacement patterns of beef heifers on Italian ryegrass pasture

The effect of supplementation on ingestive behavior and displacement patterns of beef heifers grazing on Italian ryegrass (Lolium multiflorum Lam.) pasture was evaluated. The grazing method was continuous with variable stocking rate. The experimental design was completely randomized with repeated measures on time. The supplement utilized was a commercial ration (17% CP, 21.4% NDF), daily supplied at 2 pm, in the proportion of 1% of body weight. The evaluations were made through visual observations, in four continuous periods of 24 hours. There was no difference in the bite rate between heifers with and without supplement and bite rate was higher at the end of the period of pasture utilization. Supplemented animals increased bite mass. The number of stations/minute, bites/station and the displacement patterns was influenced by forage changes along the occupation period. The ingestive behavior and displacement patterns of heifers are modified by supplementation and structural variation of the grass along its biological cycle. In the reproductive stage of Italian ryegrass, grazing time, daily number of bites and, feeding stations and time for station are similar between not supplemented and supplemented heifers.

Produção de forragem e carga animal de pastagens de Coastcross sobressemeadas com forrageiras de inverno

O objetivo nesta pesquisa foi avaliar a produção de forragem e a carga animal de quatro pastagens: Coastcross (Cynodon dactylon L. Pers.) sobressemeada com azevém (Lolium multiflorum Lam. cv. Comum); Coastcross sobressemeada com azevém e trevo-branco (Trifolium repens L., cv. Yi); azevém e trevo branco; e azevém. O experimento foi realizado no período entre 15 de maio e 24 de outubro de 2006, quando foram realizados cinco ciclos de pastejo. Utilizaram-se vacas da raça Holandesa recebendo concentrado (3,5 kg/dia) como suplemento alimentar. Nos períodos pré e pós-pastejo, foram avaliadas a massa de forragem, as composições botânica e estrutural da pastagem e a carga animal. O delineamento experimental foi inteiramente casualizado com quatro tratamentos (pastagens), duas repetições (piquetes) e cinco períodos de avaliação (pastejos). Não foram detectadas diferenças entre pastagens para as médias de massa de forragem e carga animal. As pastagens exclusivamente de azevém tiveram maiores produções de lâminas foliares de azevém. As pastagens sobressemeadas apresentaram maior produção de forragem. A sobressemeadura do azevém e do trevo-branco em Coastcross permite estender o período de utilização da pastagem anual e aumenta a produção de forragem.

Annual dry matter, metabolisable energy and nitrogen yields of six dryland pastures six and seven years after establishment

Dry matter (DM) yields, botanical composition, liveweight production and pasture quality of six grazed dryland pastures established in 2002 at Lincoln University, Canterbury, are reported for Years 6 (2007/08) and 7 (2008/09). Lucerne (Medicago sativa) yielded 14.0 t DM/ha/yr and sheep liveweight (LW) production totalled 903 (2007/08) and 1 141 kg/ha/yr (2008/09). Metabolisable energy (ME) on offer (~134 GJ/ha/yr) and N yield (>500 kg/ha/yr) from the lucerne exceeded those of grass-based pastures. Yields (9.8- 11.2 t DM/ha/yr) and liveweight production (814-912 kg/ha/yr) from cocksfoot (Dactylis glomerata) pastures established with subterranean (Trifolium subterraneum) clover were greater than all other grass-based pastures. Annual ME was 79-96 GJ/ha and N yield was 269- 316 kg/ha from the cocksfoot, subterranean clover and volunteer white clover (T. repens) components. For Year 7, the contribution of unsown weeds and grasses in cocksfoot-based pastures was ~28% of total annual yield compared with 55% in ryegrass (Lolium perenne)/ white clover pastures. Consequently, the ME and N yields from sown pasture components in ryegrass/white clover pastures were lower than those from cocksfootbased pastures. These results indicate dryland farms with lucerne and/or cocksfoot/sub clover pastures can produce higher DM yields from more persistent pasture species. Persistence led to more ME and N on offer to grazing livestock, which resulted in higher liveweight production than from the ryegrass pastures. Keywords: balansa clover, Caucasian clover, growth rates, pasture quality, T. ambiguum, T. michelianum

Annual herbage production increased 40% when subterranean clover was over-drilled into grass dominant dryland pasture

Annual dry matter (DM) production and botanical composition from dryland cocksfoot and ryegrass pastures grown with and without subterranean clover were measured over 2 years (2006-2008) in Canterbury.

Arrowleaf clover improves lamb growth rates in late spring and early summer compared with subterranean clover pastures in south-west Victoria

The profitable production of lamb from pasture-based systems is dependent on high levels of pasture production being efficiently utilised by sheep of superior genetic merit. Pastures that can extend the pasture-growing season and provide high quality feed in late spring and summer have the potential to increase production efficiency and the proportion of lambs that meet market specifications. In this paper we tested the hypothesis that arrowleaf clover (cv. Arrotas), a cultivar selected for late maturity, would supply feed of higher nutritive value than conventional annual legumes and perennial ryegrass mixtures during December and January and this would improve lamb growth rates over this period. Two experiments were conducted to compare the nutritive value of pasture and growth rates of lambs grazing arrowleaf clover, subterranean clover (cv. Leura) or subterranean clover/perennial ryegrass mixtures at different stocking rates during late spring and early summer in south-west Victoria. In the second experiment an arrowleaf clover/perennial ryegrass treatment was also included. Lambs were removed from the plots when they could no longer maintain liveweight. Arrowleaf clover extended the growing season by 4–6 weeks and provided feed of significantly higher digestibility than subterranean clover during December and January. The digestibility of arrowleaf and perennial ryegrass was comparable, but arrowleaf had significantly higher crude protein content during this period. Lambs grazing arrowleaf clover at stocking rates up to 24 lambs/ha grew at or above 100 g/day until the end of January, whereas lambs grazing subterranean clover and perennial ryegrass mixed pastures could not maintain weight by mid-to-late December in both years and were removed from the pastures. At the highest stocking rates total lamb production from arrowleaf clover monoculture pastures in late spring and early summer was ~400 kg liveweight/ha, and was more than double that achieved from the subterranean clover and perennial ryegrass/subterranean clover mixed pastures. The perennial ryegrass/arrowleaf clover mixed pastures in the second experiment produced a similar quantity of lamb per hectare as the arrowleaf clover monoculture pastures at the same stocking rate. In this paper we demonstrated that late-maturing arrowleaf clover can be a profitable, special purpose lamb-finishing pasture. Arrowleaf clover was most suited to more elevated parts of the landscape where estimated carrying capacity was 20 to 40% greater than that from lower lying parts of the landscape that were more subject to water logging and weed infestation. The risks of including arrowleaf clover pastures into the farming system could be reduced by direct drilling arrowleaf clover, which has relatively poor winter production, into existing perennial ryegrass pastures.

CARACTERÍSTICAS QUALITATIVAS DA PASTAGEM DE AVEIA PRETA E AZEVÉM MANEJADA SOB DIFERENTES ALTURAS, OBTIDA POR SIMULAÇÃO DE PASTEJO

O objetivo desse experimento foi avaliar o valor bromatológico da pastagem de aveia preta e azevémsubmetida a diferentes alturas de pastejo, obtida pela simulação de pastejo. O experimento foi conduzido naFazenda Experimental da COAMO, Campo Mourão/PR. O delineamento experimental adotado foi de blocosao acaso, com quatro tratamentos e duas repetições. Os tratamentos foram constituídos por diferentesalturas da pastagem: 7 cm de altura; 14 cm de altura; 21 cm de altura e 28 cm de altura. O método deamostragem utilizado foi a simulação manual do pastejo. Os valores médios de proteína bruta foram de23,8%; 21,8%; 20,8% e 20,9% para os tratamentos de 7 cm; 14 cm; 21 cm e 28 cm respectivamente. Aanálise de regressão demonstra que houve resposta quadrática da altura da pastagem sobre os teoresmédios de proteína bruta. Os valores médios de fibra em detergente ácido (FDA) foram de 25,5%; 28,0%;27,2% e 26,0% para os tratamentos de 7 cm; 14 cm; 21 cm e 28 cm respectivamente. E os valores de fibraem detergente neutro (FDN) foram de 58,5%; 62,2%; 59,7% e 60,5% para os tratamentos de 7 cm; 14 cm;21 cm e 28 cm respectivamente. Os valores médios de fibra em detergente ácido (FDA) e fibra emdetergente neutro (FDN) não apresentaram diferença entre as alturas de pastejo. A utilização da pastagemde aveia preta e azevém em menor altura implicou no aumento dos teores de proteína bruta da forragemobtida na simulação de pastejo dos animais.

Meat yield of culled cow and steer carcasses

The experiment evaluated the meat yield of prepared beef cuts, bone and trimmings of steer and culled cow carcasses. Culled 72-month-old Braford cows, 496 kg live weight and 36-month-old steers, 494 kg live weight were used, all from the same herd and finished on ryegrass pasture. A randomized complete design, with two treatments and 15 replications, was used. Hot carcass weight was lower for cows (248 kg) than for steers (263 kg). Steer carcasses presented better conformation, lower chilling loss, shorter (128.6 vs. 137.7 cm), with longer and thicker limbs compared to cows and similar fat finishing. Steer carcasses showed, compared to cow carcasses, always in the same order, similar side cut yield (13.5 vs. 13.4%), higher forequarter yield (38.4 vs. 37.2%), and lower hindquarter yield (48.1 vs. 48.9%), resulting lower yields of the sub-primal cuts full rump and sirloin, lower rump UK trim, rump tail and striploin. Steer and cow carcasses were similar in total yield of prepared meat cuts (77.8 vs. 77.6%), discarded bone (17.4 vs. 17.9%), discarded trimmings (4.54 vs. 4.09%), and losses inherent to the deboning process (0.34 vs. 0.34%). The results showed that cow carcasses are longer, have shorter and thinner limbs, have higher hindquarter and lower of forequarter yields, but the total yield of prepared meat cuts were similar between cow and steer carcasses.

Composição tecidual e perfil de ácidos graxos do lombo de cordeiros terminados em pasto com níveis de suplementação concentrada

A composição tecidual da carne é característica importante na avaliação da qualidade sensorial e nutricional do produto. O presente trabalho avaliou a composição tecidual e o perfil de ácidos graxos do lombo de cordeiros desmamados aos 42 dias de idade média e terminados em pasto de azevém com níveis diários de suplementação concentrada (0, 1 e 2% do PV e ad libitum). O delineamento experimental foi de blocos ao acaso com três repetições. Os cordeiros foram abatidos ao atingirem 32kg de peso vivo. O lombo direito foi utilizado para determinação da composição tecidual e o esquerdo para análise de perfil de ácidos graxos. As análises de variância e de regressão foram realizadas com auxílio do programa SAS (2001). A suplementação concentrada de cordeiros terminados em pasto não teve efeito (P>0,05) sobre o desenvolvimento muscular e ósseo; no entanto, promoveu acréscimo linear na deposição de gordura intermuscular e total. Os níveis de suplementação estudados não tiveram efeito (P>0,05) sobre a quantidade e o percentual de cada ácido graxo da carne dos cordeiros. A suplementação concentrada de cordeiros desmamados em pasto de azevém aumentou a deposição de gordura na carcaça sem afetar a qualidade da carne para o consumo humano, considerando-se o perfil de ácidos graxos.

Forage-Finished Beef Supplemented with Corn and Corn Oil

Beef steers were finished on ryegrass with corn or corn + corn oil supplementation in a 2-yr experiment to determine effects on performance and conjugated linoleic acid tissue concentration, especially cis-9, trans-11 (c9,t11). Rib steak (longissimus dorsi, LM) and subcutaneous fat (SQ) samples were analyzed for long-chain fatty acid concentrations. Angus and Angus crossbred steers (yr 1, n = 18, initial BW 369.4 ± 29.1 kg; yr 2, n = 48; initial BW 364.1 ± 1.07 kg) were backgrounded on rye pasture for 71 d (ADG 1.78 ± 0.11 kg) and 41 d (ADG 1.24 ± 0.77 kg), respectively, in yr 1 and yr 2. After rye grazing, steers were assigned to ryegrass pastures (cv. Big Daddy; yr 1: 4 pastures, 1.62 ha each; yr 2: 6 pastures, 1.46 ha each) for 83 d in yr 1 and 112 d in yr 2, and fed corn at 1% BW, without or with corn + corn oil (0.075% BW). In yr 1, steer initial BW (n = 16; 424.3 ± 27.83 kg), 83-d ADG (1.78 vs. 1.89 kg), carcass weight (347.9 vs. 354.44 kg), and QG (12.27 vs. 12.61; 12 = US Select +) were similar for corn vs. corn + corn oil treatments. In yr 2, a ryegrass-only treatment was added to the corn and corn + corn oil treatments used in yr 1. Steers (n = 37, initial BW 390.1 kg ± 27.4) assigned to ryegrass only (n = 9), corn (n = 14), or corn + corn oil (n = 14) treatments had respective 112-d ADG of 1.07, 1.65, and 1.62 kg (P < 0.01); carcass weights of 288.1, 321.4, and 326.0 kg (P < 0.01), and QG of 9.78, 10.57, and 10.29 (10 = US Select, P > 0.28). Feeding corn + corn oil decreased supplement intake in yr 1 (P < 0.03), but it did not improve ADG above feeding corn at 1% BW in either year. In yr 1, concentrations of c9,t11 were similar for corn and corn + corn oil in LM, but corn + corn oil had higher (P < 0.04) concentrations in SQ samples. In yr 2, concentration of c9,t11 was highest for LM (P < 0.03) and SQ (P < 0.02) in corn + corn oil compared with similar values for the ryegrass-only and corn treatments. Results indicate that addition of corn oil with corn may increase conjugated linoleic acid in beef steers finished on ryegrass pasture, but may not affect performance or QG.

Implementation of a Method to Determine Lolitrem-B in Ryegrass (Lolium perenne L.) by Liquid Chromatography (HPLC)

Lolitrem-B is a neurotoxic substance that causes the ryegrass staggers syndrome in cattle, sheep, and horses consuming ryegrass (Lolium perenne L.) infected with endophytic fungus Neotyphodium lolii (Latch, Christensen, and Samuels) Glenn, Bacon, and Hanlin. Due to the increasing use of ryegrass pasture in southern Chile, it is necessary to know the content of lolitrem-B to optimize grazing management and reduce the effect on animal health. The objective of this study was to implement a method to determine lolitrem-B in ryegrass. Ryegrass samples were used without the endophyte, freeze-dried, and kept in darkness at -18 oC to establish the method. Then, a pure

Restricting time at pasture: Effects on dairy cow herbage intake, foraging behavior, hunger-related hormones, and metabolite concentration during the first grazing session

This study investigated the effect of restricting grazing time on circulating concentrations of ghrelin, nonesterified fatty acids (NEFA), and glucose before, and foraging behavior of dairy cows during, the first grazing session of the day (GS, 0800–1200h). Forty-eight Holstein-Friesian cows (470±47kg of BW; 35±9 d in milk) were strip-grazed on a perennial ryegrass pasture for either 4h after each milking (2×4), 8h between milkings (1×8), or the 24-h period excluding milking times (CTL). Cows were bled before the GS; plasma was analyzed for ghrelin and serum for glucose and NEFA. Herbage mass was measured pregrazing (0730h), during and at the end of the GS (1200h), and postgrazing (24h after the first measurement). Herbage mass data were fitted to a model to estimate herbage disappearance rates. Herbage intake and bite mass were calculated using herbage mass disappearance and behavioral measurements. Bite rate, eating, searching, ruminating, and idling time were determined during the GS for each cow. No difference in glucose concentration was found between treatments. Concentrations of NEFA and ghrelin were the greatest for cows in the 1×8 treatment. Daily herbage intake did not differ between treatments; however, during the GS 1×8 had a greater herbage intake than 2×4 and CTL. Bite mass differed between treatments and throughout the GS. Bite mass was smallest for CTL during the first 60min and greatest during the last 90min, when cows in the 2×4 treatment had the smallest bite mass. Cows in 1×8 spent the longest time eating and the least time searching and ruminating. Eating time was greatest for 1×8 during the first 60 and last 90min of the GS. Searching time only differed in the second 60min, when it was the lowest for 1×8. Cows from all treatments did not ruminate during the first 120min. Cows in CTL had the greatest rumination time during the last 90min. The model fitted to represent dynamics of herbage mass disappearance presented differences in the fractional herbage disappearance rate. There was an interaction between treatment and time in herbage depletion rate. The results of this study present a fuller picture of foraging dynamics during the first 4h of grazing and its potential relationship with physiological markers of hunger as affected by grazing management.

Restricting daily time at pasture at low and high pasture allowance: Effects on pasture intake and behavioral adaptation of lactating dairy cows

In pasture-based dairy systems, daily time at pasture is restricted during several periods of the year. The aim of this experiment was to evaluate the effect of restricting time at pasture on milk yield, pasture dry matter (DM) intake, and grazing behavior of dairy cows according to pasture allowance (PA), which partly defines pasture availability. The experiment was carried out in spring on strip-grazed perennial ryegrass pastures. The 6 treatments consisted of 3 durations of daily time at pasture [U: unrestricted day and night grazing (22h at pasture); R9: 1 grazing session restricted to 9h between the 2 milkings; R5: 2 grazing sessions of 2.75h after each milking) compared at low and high PA (13 and 24kg of DM/d per cow >5cm, respectively). Eighteen mid-lactation Holstein dairy cows were used according to a 6 × 4 incomplete Latin square design replicated 3 times with four 14-d periods. Pasture DM intake was measured by the ytterbium-fecal index method and grazing behavior from portable devices. On average, restricting time at pasture from U to R (mean of R5 + R9) decreased pasture intake by 2.9kg of DM, milk yield by 1.3kg, and milk protein concentration by 0.11%, and increased milk fat concentration by 0.20%. Pasture intake and milk yield did not differ significantly between R9 and R5. The reduction of pasture intake and milk yield with decreasing time at pasture was greater at high compared with low PA. Grazing times were 536, 414, and 305min, representing proportions of time spent grazing of 0.40, 0.77, and 0.93 for treatments U, R9, and R5, respectively. The reduction of grazing time with decreasing time at pasture was greater at high compared with low PA. Pasture intake rate greatly increased with decreasing time at pasture, but mainly on R5 (29.8, 31.6, and 42.1g of DM/min for U, R9, and R5, respectively). The effect of time at pasture on pasture intake rate was unaffected by PA. In conclusion, the effect of restriction of time at pasture on pasture intake and milk yield becomes more marked as PA increases. Cows offered only 2 grazing sessions of 2.75h after each milking maximized pasture intake rate and consumed pasture as much as in one 9-h grazing session.

Valor nutricional de forragem de pastagens manejadas durante o período hibernal

O objetivo nesta pesquisa foi avaliar o valor nutritivo, determinando-se a matéria orgânica (MO), digestibilidade in vitro da MO (DIVMO), nutrientes digestíveis totais (NDT), digestibilidade in vitro da matéria seca (DIVMS), proteína bruta (PB) e fibra em detergente neutro (FDN), de quatro sistemas forrageiros (tratamentos), pastejados por vacas da raça Holandesa. Os tratamentos foram constituídos por "coastcross" (Cynodon dactylon L. Pers.) sobresemeada com azevém (Lolium multiflorium Lam. cv. 'Comum'); coastcross sobresemeada com azevém e trevo branco (Trifolium repens L., cv. 'Yi'); azevém mais trevo branco e apenas azevém. Entre 15 de maio e 24 de outubro de 2006, foram conduzidos cinco ciclos de pastejo, sendo avaliada a massa de forragem de pré-pastejo (MF), as composições botânica e estrutural e lotação (L). Para análise do valor nutritivo, foram coletadas amostras de pastejo simulado. O delineamento experimental foi inteiramente casualizado com quatro tratamentos e duas repetições (piquetes). Não foram detectadas diferenças entre os tratamentos para as médias de MF e L. Observou-se que os melhores resultados de valor nutritivo estão associados à biomassa de lâmina foliar de azevém em todas as pastagens. Verificaram-se pequenas diferenças no valor nutritivo entre as pastagens sobresemeadas em comparação ao azevém e trevo branco ou azevém. Os valores médios de MO, DIVMO, NDT, DIVMS, PB e FDN das pastagens foram de 89,52; 69,50; 60,95; 70,96; 23,03 e 51,87%, respectivamente.

Potential use of Acacia mearnsii condensed tannins to reduce methane emissions and nitrogen excretion from grazing dairy cows

We measured the effect of condensed tannins (CT) extracted from the bark of the Black Wattle tree (Acacia mearnsii) on the milk production, methane emissions, nitrogen (N) balance and energy partitioning of lactating dairy cattle. Sixty lactating cows, approximately 32 d in milk grazing ryegrass pasture supplemented with 5 kg d-1 cracked triticale grain, were allocated to three treatments: Control, Tannin 1 (163 g CT d-1) or Tannin 2 (326 g CT d-1 initially, reduced to 244 g d-1 CT by day 17). Cows were dosed twice daily after milking for 5 wk with the powdered CT extract (mixed 1:1 with water). Low and high CT supplementation reduced (P &lt; 0.05) methane emissions by 14 and 29%, respectively (about 10 and 22% on an estimated dry matter intake basis). However, milk production was also reduced by the CT (P &lt; 0.05), especially at the high dose rate. Milk yields were 33.0, 31.8 and 29.8 kg cow-1 d-1. Tannin 2 also caused a 19% decline in fat yield and a 7% decline in protein yield, but protein and lactose contents of milk were not affected by CT supplementation. After the initial 5-wk period, five cows representative of each treatment group were moved to metabolism facilities to determine effects of CT on energy digestion and N balance over 6 d. The energy digestibility was reduced (P &lt; 0.05) from 76.9 (Control) to 70.9 (Tannin 1) and 66.0% (Tannin 2) and the percentage of feed N lost to urine was reduced (P &lt; 0.05) from 39 to 26% and 22% for the respective treatments. The CT also caused a reduction (P &lt; 0.05) in intake during the metabolism study, effectively increasing CT as a percentage of intake. Although CT can be used to reduce methane and urinary N losses from cows fed pastures with a high crude protein (CP) concentration, reduced milk yield in this study suggested the dietary concentration was too high. If CT are to be considered as a means for lowering methane emissions further research is needed to define impacts of lower doses of A. mearnsii CT on methane production and cow productivity. Dairy producers will be reluctant to adopt feeding practices that compromise profitability.Key words: Dairy cow, condensed tannins, methane, milk production, energy, nitrogen balance

Finishing steers on winter annual ryegrass (Lolium multiflorum Lam.) with varied levels of corn supplementation I: Effects on animal performance, carcass traits, and forage quality

Crossbred steers (n = 72) were selected to study forage-based finishing systems using winter annual ryegrass (Lolium multiflorum Lam.) with varying levels of grain supplementation. In December, cattle were allotted to 1 of 6 treatments consisting of ryegrass pasture (1 ha) with whole shell corn supplemented at 0.0% (0.0), 0.5% (0.5), 1.0% (1.0), 1.5% (1.5), and 2.0% (2.0) of BW, or an ad libitum mixed-ration grain diet in a drylot. Steers were randomly assigned to pens of 4 with pen serving as the experimental unit. Cattle were slaughtered by pen when average pen backfat thickness (as measured by real-time ultrasound) reached approximately 0.64 cm. Forage samples and disk meter height were taken from ryegrass paddocks on a monthly basis to determine forage quality and mass. Live animal performance, carcass traits, proximate analysis, Warner-Bratzler shear force, and sensory characteristics from the LM of the rib section were analyzed. Increasing the amount of grain in the diet of finishing cattle resulted in a linear decrease (P < 0.05) in days on feed and a linear increase (P < 0.05) in ADG, preliminary yield grade, final yield grade, flavor intensity, and beef flavor. Forage DM mass increased with each incremental increase in grain added to the grazing diets. Quality of forage was not (P > 0.05) affected by adding grain to the diet. Adding corn to the diet of cattle being finished on forage improved animal performance and decreased forage utilization characteristics in addition to improving the flavor characteristics of beef.

Desenvolvimento e desempenho reprodutivo de vacas primíparas aos 22/24 meses de idade

Objetivou-se avaliar sistemas de alimentação para 70 novilhas de corte do início da gestação, aos 13/15 meses de idade, até o final do segundo período reprodutivo como vacas primíparas, aos 22/24 meses de idade. O delineamento experimental foi inteiramente casualizado com parcelas subdivididas no tempo considerando os animais como repetições. O peso vivo médio inicial foi de 282 kg e a condição corporal inicial de 3,2. Os sistemas de alimentação avaliados foram estabelecidos visando maior ganho de peso em pastagem cultivada na fase inicial (PCIG) ou final (PCFG) da gestação: PCIG - novilhas em pastagem de milheto (Pennisetum americanum, L.) durante a fase inicial da gestação e em pastagem natural no pré-parto; PCFG - novilhas em pastagem natural durante a fase inicial da gestação e em pastagem de aveia-preta (Avena strigosa Schreb) e azevém (Lolium multiflorum Lam) no pré-parto. Na fase inicial da gestação, o ganho de peso médio diário (GMD) de 0,424 kg das PCIG foi superior ao de 0,245 kg das PCFG. No pré-parto, as novilhas do sistema PCIG perderam peso, 0,303 kg/dia e condição corporal 0,77 ponto, enquanto as PCFG ganharam 0,901 kg/dia de PV e 0,37 ponto de CC. O peso vivo de 323 kg e a condição corporal de 3,3 pontos das novilhas do sistema PCFG pós-parto foram superiores aos das novilhas do sistema PCIG, de 274 kg e 2,6 pontos, respectivamente. As novilhas do sistema PCFG pariram bezerros 4 kg mais pesados e, ao início do período reprodutivo, apresentaram a mais 35 kg e 0,6 ponto de condição corporal. A taxa de prenhez de 85% das PCFG foi superior à de 53% das PCIG. As vacas prenhes foram as com maior condição corporal ao parto e ao início do segundo período reprodutivo, apresentaram maior intervalo do parto ao acasalamento e pariram bezerros mais pesados.

Características da pastagem de azevém e produtividade de cordeiros em pastejo

Objetivou-se avaliar a produção da pastagem de azevém, a qualidade da forragem e a produtividade animal por área em três sistemas de produção: cordeiros desmamados precocemente, aos 40 dias de idade, e mantidos em pastagem de azevém (Lolium multiflorum Lam.) até o abate; cordeiros sem desmame, mantidos na mesma pastagem de azevém até o abate; cordeiros sem desmame recebendo suplemento (1% do peso vivo) em creep feeding a partir dos 40 dias de idade. O sistema de pastejo utilizado foi o de lotação contínua com carga animal variável, mantendo-se a oferta de massa de lâminas foliares em 1.000 kg de MS/ha. A produção média de massa seca da pastagem foi 3.236,6 kg MS/ha, a de lâminas foliares, de 1.008,7 kg MS/ha, e a taxa de crescimento do pasto, de 58,38 kg MS/ha/dia. Com cordeiros desmamados, a altura média da pastagem foi de 20,95 cm, significativamente maior que a daquela com cordeiros sem desmame. A massa de inflorescências nas pastagens dos cordeiros desmamados foi superior (61,7 kg/ha) quando comparado aos outros sistemas. O sistema de terminação de cordeiros desmamados permitiu maior carga animal (929,74 kg PV/ha) em comparação aos demais, considerando apenas os cordeiros sem suplementação (259,9 kgPV/ha) ou com suplementação em creep feeding (254,3 kgPV/ha). A qualidade da forragem não diferiu entre os sistemas de terminação. A estrutura da pastagem sofreu alterações na ausência das ovelhas, devido à maior seletividade dos cordeiros. O sistema de terminação em pastagem com desmame precoce foi o menos produtivo, em razão do baixo desempenho individual dos cordeiros, por isso, não deve ser recomendado a ovinocultores.

Silagem de milho e grão de sorgo como suplementos para vacas de descarte terminadas em pastagem cultivada de estação fria

Avaliou-se o efeito da suplementação com silagem de milho ou grão de sorgo no desempenho e características da carcaça e da carne de vacas de descarte, submetidas ao pastejo restrito em pastagem de aveia (Avena strigosa) + azevém (Lolium multiflorum). Foram utilizadas 30 vacas mestiças Charolês-Nelore, com idade média de oito anos, distribuídas em igual número e ao acaso em três tratamentos: silagem de milho (TSI) ou grão de sorgo moído (TSO) como suplemento, e não suplementação (TPH). A suplementação com silagem de milho proporcionou aos animais maior escore corporal ao final do experimento (4,35 pontos contra 4,15 do TPH e 4,22 pontos para o TSO). Não houve efeito do volumoso ou concentrado suplementar sobre o peso corporal, ganho de peso diário e ganho em escore corporal. Não houve efeito de tratamento (P&gt;0,05) sobre pesos e rendimentos quentes e frios da carcaça, espessura de gordura subcutânea, conformação, espessura de coxão, área de Longissimus dorsi e percentagem de cortes comerciais. A suplementação resultou em maior percentagem de gordura na carcaça e influenciou a cor e o marmoreio da carne. A silagem de milho e o grão de sorgo servem como alternativa para a suplementação de vacas de descarte em pastagem de aveia e azevém, uma vez que melhora as características da carcaça, embora sem efeito sobre o desempenho quando comparado à pastagem exclusiva.

Desenvolvimento de novilhas de corte sob alternativas de mineralização em pastagem de azevém

Foi avaliado o desenvolvimento corporal de bezerras de corte em pastagem de azevém (Lolium multiflorum Lam.), recebendo diferentes alternativas de suplementação mineral, associadas ou não à adição de ionóforo. Os tratamentos testados foram: "Sal comum": mineralização com cloreto de sódio; "Sal 40P": mineralização com sal mineral contendo 40g de fósforo por kg de produto; "Sal 40P + ionóforo": mineralização com 40g de fósforo + 2.000mg de lasalocida sódica por kg de produto. Os valores de proteína bruta, fibra em detergente neutro, Ca e P na forragem aparentemente consumida, consumo de sal, escore de condição corporal, relação peso: altura e GMD foram semelhantes (P&gt;0,05) entre animais que receberam "Sal comum", "Sal 40P" e "Sal 40P + ionóforo". Em pastagem de azevém, sem restrição ao consumo voluntário, a lasalocida sódica adicionada ao sal mineral proporciona maior peso vivo de bezerras aos 12 meses de idade e um retorno financeiro positivo.