Pasture Intake Research Articles

Milk production responses to different strategies for feeding supplements to grazing dairy cows

Milk production responses of grazing cows offered supplements in different ways were measured. Holstein-Friesian cows, averaging 45d in milk, were allocated into 8 groups of 24, with 2 groups randomly assigned to each of 4 feeding strategies. These were control: cows grazed a restricted allowance of perennial ryegrass pasture supplemented with milled wheat grain fed in the milking parlor and alfalfa hay offered in the paddock; FGM: same pasture and allowance as the control supplemented with a formulated grain mix containing wheat grain, corn grain, and canola meal fed in the parlor and alfalfa hay fed in the paddock; PMRL: same pasture and allowance as the control, supplemented with a PMR consisting of the same FGM but mixed with alfalfa hay and presented on a feed pad after each milking; and PMRH: same PMR fed in the same way as PMRL but with a higher pasture allowance. For all strategies, supplements provided the same metabolizable energy and grain:forage ratio [75:25, dry matter (DM) basis]. Each group of 24 cows was further allocated into 4 groups of 6, which were randomly assigned to receive 8, 12, 14, or 16kg of DM supplement/cow per d. Thus, 2 replicated groups per supplement amount per dietary strategy were used. The experiment had a 14-d adaptation period and a 14-d measurement period. Pasture allowance, measured to ground level, was approximately 14kg of DM/d for control, FGM, and PMRL cows, and 28kg of DM/d for the PMRH cows, and was offered in addition to the supplement. Positive linear responses to increasing amounts of supplement were observed for yield of milk, energy-corrected milk, fat, and protein for cows on all 4 supplement feeding strategies. Production of energy-corrected milk was greatest for PMRH cows, intermediate for FGM and PMRL cows, and lowest for control cows. Some of these differences in milk production related to differences in intake of pasture and supplement. Milk fat concentration decreased with increasing amount of supplement for all feeding strategies, but the decline was most marked for the control cows. Milk protein concentration increased for all groups as the amount of supplement increased, but was greater for FGM, PMRL, and PMRH cows than control cows. It is concluded that when supplements are fed to grazing dairy cows, inclusion of corn grain and canola meal can increase milk production even at similar metabolizable energy intakes, and that it does not matter whether these supplements are fed as a PMR or in the parlor and paddock.

Variation of milk components in the Italian Brown cattle.

The aim of this study was to evaluate the variations of protein, casein, saturated (SFA), unsaturated (UFA), monounsaturated (MUFA), polyunsaturated (PUFA) fatty acids contents and cheese yield in the milk of two groups of Italian Brown cows conventionally reared in indoor period of housing or consuming pasture during the summer months in 2008 and 2013. Milk components were obtained from samples collected during the national routine (conventionally reared) and 'extraordinary' (pasture period) milk recording scheme in herds located near Sondrio (Lombardia, Italy). Milk samples were processed with the MilkoScanTM FT6000 for the identification of milk casein, SFA, UFA, MUFA and PUFA composition. The groups were analysed separately per year and the environmental factors affecting milk protein, casein, and fatty acids contents (pasture/indoor, parity, data of sampling, days in milk, days from collection to analysis) were included in the MIXED procedure of SAS 9.3. A total of 778 milk samples were available, including 234 records from indoor and 544 observations from pasture feeding. Pasture intake affected the content of casein (%) and the proportion of fat in milk (g/100 g), enhancing milk casein levels (from 2.90 to 3) and reducing the concentration of milk SFA in milk from grazing cows (from 2.29 to 1.92). Additionally, the cheese yield was calculated as 'kg of cheese per 100 kg of milk' and resulted to be 10.4 and 12 in 2008 from milk of cows reared indoor and with pasture based diet, respectively. The dairy industry should take advantage of the milk production during grazing periods from which high quality products may be obtained.

Effects of Grazing Muzzles on Intakes of Dry Matter and Water-Soluble Carbohydrates by Ponies Grazing Spring, Summer, and Autumn Swards, as well as Autumn Swards of Different Heights

Dry matter (DM) and water-soluble carbohydrate (WSC) intakes (DMI and WSCI, respectively) were determined in four mature ponies, grazing spring, summer, and autumn pastures on four, 3-hour occasions per pony per season when fitted with or without a grazing muzzle. Pasture intakes were determined by change in liveweight (LW) over the 3-hour grazing period, after accounting for insensible weight loss and weight of excreta. Daily pasture samples were analyzed for DM and WSC. The effect of sward height on herbage intake characteristics by muzzled or unmuzzled ponies allowed 10 single bites of short (ca. 7 to 10 cm), medium (ca. 20 cm), and long (ca. 40 cm) swards was also investigated. Grazing muzzles significantly (P < .01) reduced pasture DMI by 77, 77, and 83% for spring, summer, and autumn pastures, respectively. During at least one 3 hour grazing session across the seasons, the DMI of each pony when not muzzled exceeded 1% of LW. Water-soluble carbohydrate intakes (g WSCI/100 kg LW/3 hours) were significantly lower (P < .05) across seasons when ponies were muzzled versus unmuzzled. When unmuzzled, ponies' WSCI from summer swards were significantly (P < .05) lower than from autumn swards. Seasonal differences in WSCI by muzzled ponies were not significant. When unmuzzled ponies grazed swards of different heights, the first bite generally reduced sward length by approximately half. However, when muzzled, first bites of swards resulted in highly variable reductions in sward length. Ponies appeared to experience greater difficulty in accessing the longer versus the shorter swards via their grazing muzzles.

Metabolic and endocrine profiles and hepatic gene expression of Holstein cows fed total mixed ration or pasture with different grazing strategies during early lactation.

BackgroundIn dairy mixed production systems, maximizing pasture intake and total mixed ration (TMR) supplementation are management tools used to increase dry matter and energy intake in early lactation. The objective was to evaluate metabolic and endocrine profiles and hepatic gene expression of Holstein cows fed either TMR ad libitum (without grazing) or diets combining TMR (50 % ad libitum DM intake) and pasture with different grazing strategies (6 h in one grazing session or 9 h in two grazing sessions) in early lactation. Pluriparous cows were grouped by calving date, blocked within group by body weight and body condition score (BCS) and randomly assigned to one of three feeding strategies from calving (day 0) to 60 days postpartum: control cows fed TMR ad libitum (G0; confined cows fed 100 % TMR without access to pasture), pasture grazing with 6 h of access in one session supplemented with 50 % TMR (G1), and 9 h of access in two sessions supplemented with 50 % TMR (G2).ResultsNet energy (NE), but not metabolizable protein (MP), demands for maintenance and/or milk increased in G2 when compared with G1 and G0 cows, respectively. However, NE and MP balances were lower in G1 and G2 than G0 cows. Cow BCS at +55 days was greater in G0 than G2 cows and probability of cows cycling during the first month was greater in G0 and G1 than G2 cows. During the postpartum period, non-esterified fatty acids were greater in G1 than G2 and G0 and β-hydroxybutyrate was greater in G1 and G2 than G0 cows. Plasma insulin was greater and insulin-like growth factor (IGF)-I tended to be greater in G0 than G2 cows, leptin was greater in G2 and G0 and adiponectin were greater in G2 cows. Hepatic expression of growth hormonereceptor-1A and IGF1 mRNA decreased while IGF binding proteins 1,2,4,5 and 6 (IGFBP) mRNA as well as mRNA expression of insulin, leptin (LEPRb) and adiponectin-2 receptors increased from pre to postpartum in all cows. However, only hepatic IGFBP6 and LEPRb mRNA were greater in G2 than G0 and G1 cows, respectively.ConclusionMetabolic-endocrine profiles of cows with different feeding strategies in early lactation reflected not only changes in milk energy output and energy balance but also in walking and grazing activity. Concentrations of insulin and IGF-I were increased in G0 cows whereas plasma adiponectin and both, insulin and leptin sensitivity were improved G2 cows. Increased NE demands in G2 cows when compared to G1 and G0 cows, implied a metabolic stress that impacted negatively on reproductive function.Electronic supplementary materialThe online version of this article (doi:10.1186/s13028-015-0163-6) contains supplementary material, which is available to authorized users.

Desempenho nutricional de bovinos em pastejo durante o período de transição seca-águas recebendo suplementação proteica

Objetivou-se avaliar os efeitos do fornecimento de quantidades crescentes de suplemento proteico durante o período de transição seca-águas sobre o consumo, a digestibilidade e sobre aspectos do metabolismo de compostos nitrogenados em bovinos. Foram utilizados cinco novilhos Nelore com peso corporal (PC) inicial de 273 kg, fistulados no rúmen e mantidos individualmente em piquetes de capim-braquiária com 0,34 ha. O experimento foi estruturado em delineamento em quadrado latino 5 × 5. Os tratamentos foram definidos de maneira a suplementar os animais em 0; 1,25; 2,5; 5,0 e 10,0 g de suplemento por kg de PC. O suplemento foi composto por farelo de soja, milho, ureia e sulfato de amônio de forma a apresentar 340 g de proteína bruta (PB)/kg de matéria natural. Verificou-se que os consumos de matéria orgânica (MO), PB e MO digerida foram incrementados linearmente (p0,10) sobre o consumo de pasto. A digestibilidade total e ruminal da MO e PB foi incrementada linearmente (p

Salinomycin and virginiamycin for lactating cows supplemented on pasture

Animals on pasture generally show higher feed efficiency as a result of the use of antibiotics. This study evaluated the effect of the antimicrobials salinomycin and/or virginiamycin on production and the ruminal parameters of supplemented dairy cows grazing on Panicum maximum cv. Tanzania. Twelve Holstein/Zebu multiparous cows were used, distributed in three Latin squares, one for the evaluation of ruminal parameters, and the others for production parameters. Cows on pasture were fed 50 % of their estimated intake with corn silage and concentrate supplements containing salinomycin, virginiamycin or a combination of additives, in doses of 120 and 150 mg kg−1, respectively. There were no differences in milk production and composition, energy and nitrogen balance, dry matter digestibility and feeding behavior. However, salinomycin and virginiamycin each reduced pasture and total dry matter intake by about 14 % and 10 %, with a consequent improvement in feed efficiency.

Optimising the interrelationship between intake per cow and intake per hectare

Production and profit in grazed systems remain inherently constrained by the fundamental trade-off between maximising individual herbage intake and pasture utilisation. The primary objective of this paper is to investigate the trade-off between herbage intake per cow and intake per hectare, from the perspective of economic optimisation, for an intensive pasture-based dairy farm in New Zealand (NZ). A detailed optimisation model of a dairy farm is applied, to allow the complex animal–plant–supplement dynamics underlying this relationship to be explicitly considered. Model output confirmed the existence of the fundamental inverse relationship between individual cow intake and herbage utilisation, which arises from the underlying biophysical dynamics within a grazing system, in the context of pasture-based NZ dairy farms. Results indicated that profitable management relies on increasing total pasture eaten (grazing plus pasture silage harvested on farm) through the use of a relatively high stocking rate and moderate levels of pasture intake per cow. Indeed, for 450 kg liveweight cows, optimal pasture intake per cow is 5 t dry matter (DM) per cow for per hectare intakes of 12–16 t DM/ha and 4.5 t DM/cow for a per hectare intake of 17 t DM/ha. Thus, a goal to maximise both individual intake and herbage utilisation in grazing systems is misinformed; it is the latter that is principally important to farm profit. Indeed, seeking to maximise both simultaneously is not possible, and trying to maximise individual intake can impose an enormous cost. However, while high herbage utilisation increases profit, this can also be associated with greater nutrient leaching, reinforcing the importance of considering the environmental impacts of grazing management.

Processamento do milho para vacas leiteiras em pastejo

Doze vacas lactantes Holandês-Gir (1/2), em sistema de pasto rotativo de Panicum maximumcv. Mombaça, foram suplementadas com concentrados contendo milho seco finamente moído (MM), milho expandido (ME), milho floculado a vapor (MF) ou milho moído reidratado e ensilado (MU). O delineamento experimental adotado foi o de quadrado latino 4 x 4, com três repetições. O consumo de pasto foi maior quando as vacas foram suplementadas com MF, o que se refletiu em maior consumo de MS, PB, FDN para o mesmo tratamento. A digestibilidade aparente da MS foi maior para as dietas de MF e MM. A digestibilidade aparente da FDN foi menor para MU. A produção e composição do leite das vacas não diferiram entre os tratamentos, entretanto a eficiência alimentar foi menor para MF.

A 2-year study on milk quality from three pasture-based dairy systems of contrasting production intensities in Wales

SUMMARYThere is an increasing interest in pasture-based dairy systems in Europe, mainly because of increasing production costs for intensive dairying. Milk is a matrix of compounds that influence nutritional and manufacturing properties, many dependent on husbandry linked to pasture-based systems (increase in pasture intake, forage : concentrate ratio, clover inclusion in swards/silages and use of alternative dairy breeds). The present study investigated the impact of three grazing-based dairy systems with contrasting feeding intensity or reliance on pasture intakes (conventional high-intensity, low pasture intake [CH], organic medium-intensity, medium pasture intake [OM], conventional low-intensity, high pasture intake [CL]) on milk fatty acid (FA) profiles, protein composition and α-tocopherol and antioxidants concentrations. The proportion of animals of alternative breeds (e.g. Jersey) and crossbred cows in the herd increased with decreasing production intensity (CH &lt; OM &lt; CL). Milk constituents known to be beneficial for human health, such as vaccenic acid, rumenic acid, monounsaturated FA, polyunsaturated FA, antioxidants and caseins, were elevated with decreasing production intensity (CH &lt; OM &lt; CL), while less desirable saturated FA were lower, although not all differences between OM and CL were significant. Omega-3 FA were maximized under OM practices, primarily as a result of higher clover intake. Increases in pasture intake may explain the higher concentrations of desirable FA while increased use of crossbreed cows is likely to be responsible for higher total protein and casein content of milk; a combination of these two factors may explain increased antioxidant levels. The higher concentrations of vaccenic acid, rumenic acid, omega-3 FA, lutein, zeaxanthin, protein and casein in OM and CL milk were found over most sampling months and in both years, reinforcing the higher nutritional quality and manufacturing properties associated with milk from these systems. A switch to pasture-based dairy products would increase the intake of milk's beneficial compounds and reduce consumption of less desirable saturated FA.

Hind genotype influences on lactation and calf growth in farmed red deer (Cervus elaphus)

Multiparous red deer (Cervus elaphus scoticus) hinds (n=18) were artificially inseminated with semen from a red deer stag (n=8) or wapiti bull (C.e. nelsoni) (n=10) to produce red deer or F1 crossbred (C.e. scoticus×C.e. nelsoni) calves. A further seven wapiti×red deer (F1) hinds were artificially inseminated with semen from an unrelated F1 stag to test the hypotheses that (1) crossbred hinds rearing crossbred calves will produce more milk to support calf growth than red deer hinds rearing crossbred calves, and (2) the extra lactation demand of crossbred calves will exert a more detrimental effect on red deer hind live weight and body condition than would occur if the dam was a crossbred hind. Hinds and calves were grazed on ryegrass and white clover pastures and supplemented with pasture silage and barley grain when pasture supply was inadequate. Calves were left with their mothers until approximately 240 days of age. Mean body condition score (BCS) was lower in F1 hinds rearing F2 calves during late lactation (days 150 to 240, P<0.05) than red deer hinds rearing either red deer or F1 calves. F1 calves grew significantly faster than red deer calves and were heavier at all ages, while F2 calves were intermediate. Milk intake of both F1 and F2 calves was higher than red deer calves until day 76 of lactation (P>0.05), but similar thereafter. Male calves had a higher milk intake than female calves at 20 days of age only (P=0.004). The average hind pasture intake was greatest in F1 hinds rearing F2 calves, intermediate in red deer hinds rearing F1 calves and lowest in red deer hinds rearing red deer calves (P=0.038). Total milk output for the lactation increased by approximately 14.6kg/kg average calf live weight at weaning for both F1 hinds rearing F2 calves (P=0.008) and red deer hinds rearing red deer calves (P=0.072), suggesting that calf demand rather than hind liveweight was the key determinant of lactation performance. This was not the case for red deer hinds rearing F1 calves suggesting that there is an upper limit to lactation output depending on hind size. These results do not support the hypothesis that a crossbred hind rearing a crossbred calf will produce more milk than a red deer hind rearing a crossbred calf and provides evidence that the milk production of the hind is primarily driven by milk demand of the calf but has an upper limit depending on the size of the hind. The second hypothesis was not supported as F1 hinds rearing F2 calves exhibited greater loss of body condition score relative to the red deer hinds rearing either red deer or F1 calves in this study. This suggests that the additional energetic demands on a hind from feeding an F1 calf may be met with adequate nutrition.

Consumo de forragem por novilhas de corte recebendo farelo de arroz com e sem ionóforo

O consumo de forragem foi avaliado em novilhas de corte exclusivamente em pastagem de azevém (Lolium multiflorum Lam.) ou recebendo farelo de arroz integral (FAI) com ou sem adição de ionóforo. Foi usado o óxido de cromo como indicador da produção fecal. O delineamento experimental foi o inteiramente casualizado, com medidas repetidas no tempo, com três tratamentos e três repetições de área. Os animais foram considerados as unidades experimentais nas avaliações de consumo. O consumo de pasto pelas novilhas foi similar nos diferentes sistemas alimentares, ocasionando taxa de lotação semelhante. O fornecimento de farelo de arroz integral, com ou sem monensina, aumenta o consumo de matéria seca total. A adição de ionóforo ao FAI aumenta o desempenho individual das novilhas, sendo o seu uso recomendado quando existe o objetivo de reduzir a sua idade ao primeiro acasalamento.

Effect of restricted time at pasture and indoor supplementation on ingestive behaviour, dry matter intake and weight gain of growing lambs

Herbage intake and production performance of animals are likely to vary between different levels of time grazing pasture because of related changes in foraging behaviour. The effect of restricting pasture access on ingesting behaviour and performance of growing lambs is poorly understood. Thirty-two castrated male Ujumuqin lambs were randomly assigned to the following four treatments: (i) 2-h access to pasture (2H), (ii) 4-h access to pasture (4H), (iii) 8-h access to pasture (8H), and (iv) 12-h access to pasture (12H; control). The lambs began to access pasture at 6:00h and were removed at 8:00h, 10:00h, 14:00h and 18:00h for 2H, 4H, 8H and 12H treatments, respectively. All lambs off the pasture were housed and separately fed supplements of concentrate and grass hay. The results showed that ingestive behaviour of lambs was significantly affected by restricting access to pasture. When time at pasture reduced from 12 to 2h, the proportion of time grazing pasture increased (P<0.001), as did the pasture intake rate (P<0.001), but the proportion of time resting and standing and walking distance decreased (P<0.001). Significant linear relationship was found between supplement and pasture intakes. On average, total feed intake and metabolisable energy intake were unaffected by restricting pasture access, but in July weight gain of lambs clearly increased with less time at pasture. Grazing lambs with supplementation have a good ability to adapt to the restricted grazing schedules through varying their ingestive behaviour. Overall, the results indicate shorter grazing times and higher supplementation in July, with longer grazing times and lower supplementation through August and September is the most efficient to maintain higher lamb growth rates.

Intake, milk production and weight change curves for lactating Holstein x Zebu cows under grazing

The purpose of this study was to evaluate feed intake and develop lactation and weight change curves for Holstein x zebu cows under grazing. Eighteen F1 cows were used, divided into three treatments; 6 were Holstein x Gir (HGI), 6 were Holstein x Guzerat (HGU), and another 6 were Holstein x Nelore (HNE), under the feeding conditions of pasture plus concentrate with 22% of crude protein (CP). To estimate individual feed intake at pasture, 2 markers were used: titanium dioxide to estimate fecal dry matter (DM) excretion, and the indigestible acid detergent fiber (iADF) to estimate individual pasture intake. The Wood (1967) model was used to evaluate milk yield and the parameters were estimated for each genetic group, as follows: HGI = 17.2667*t0.0652*e-0.00424t; HGU = 18.1470*t0.0332*e-0.00408t; and HN = 14.2836*t0.1059*e-0.00552t. The NEFA contents varied according to different genetic groups (P&lt;0.001). It was concluded that the estimated peak DMI occurs during the sixth week of lactation, when the DMI by the different genetic groups was stabilized. The HGI cows have greater cumulative production at 305-d.

Improving the profitability of Waikato dairy farms: Insights from a whole-farm optimisation model

High milk volumes are encouraged in the New Zealand dairy industry to promote market access and utilise processing capacity. A detailed, nonlinear optimisation model of a pasture-based dairy farm in the Waikato region is used to: (1) assess the implications of maximising operating profit, (2) evaluate the cost of maintaining a focus on producing high milk volumes, and (3) characterise general management practices that maximise operating profit. Maximising milk volume within the simulated farm system reduces operating profit by 12%–23%, due to higher production costs. Nine principles for profitable management are developed, based on model output. These focus on the use of a medium to medium-high stocking rate (3–3.7 cows ha−1) to promote the growth, quality, utilisation, and intake of pasture. Imported concentrate is valuable to augment production in mid-lactation, but it is best to avoid feeding cows to potential given the high cost of supplement.

Space allowance and barriers influence cow competition for mixed rations fed on a feed-pad between bouts of grazing

The objective of this experiment was to evaluate how feeding space allowance and provision of feed barriers interact to affect feeding and social behavior of dairy cows fed a partial mixed ration on a feed-pad. The treatments were factorial with 3 feeding space allowances (0.6, 0.75, or 1.0m of trough space per cow) and feed troughs that were either open or had head barriers that physically separated adjacent cows to reduce interactions during feeding. One hundred and forty-four Holstein-Friesian cows in mid lactation were allocated into 12 groups of 12 cows, with 1 of 6 treatments (3×2) randomly assigned to 2 groups out of 12. Treatments were changed weekly over 3 wk according to a row-column, crossover design, with week corresponding to rows and group corresponding to columns. Thus, the design included 2 replicated groups per treatment in each week. Grazed pasture intake was approximately 6.1kg of dry matter (DM)/cow per day, supplemented with 3.5kg of DM/cow per day of wheat (Triticum aestivum) grain fed during milking and 10.7kg of DM/cow per day of a mixed ration offered on the feed-pad after each milking. The experiment comprised a 7-d pre-experimental period followed by a 21-d experimental period. The social hierarchy within each group was determined before the experiment commenced. Feeding and social behaviors of cows were analyzed using video recordings and the changes in heart rate and heart rate variability were determined using heart rate monitors. Data were analyzed using mixed effect models by REML. When feeding space allowance was increased, we observed an increase in the time a cow spent feeding and a decrease in the number of feeding bouts in relation to the total time feed was available, particularly in subordinate cows. The number of aggressive behaviors and displacements decreased when space allowance increased. In addition, HR was reduced and the reduction was more pronounced in subordinate cows compared with dominant cows. Use of feed barriers increased cow feeding time and decreased the number of feeding bouts in relation to the total time feed was available, particularly in subordinate cows, and reduced the number of cow displacements during feeding. We conclude that increasing the feeding space from 0.6 to 0.75 to 1.0m reduces aggressive interactions and improves cow feeding behavior, with the effects being greatest for subordinate cows. The use of feed barriers further reduces competition at the feed trough in a partial mixed ration feeding system.

Intake estimation of horses grazing tall fescue (Lolium arundinaceum) or fed tall fescue hay

Six mature geldings of light horse breeds (557 ± 37 kg) were randomly assigned to a nontoxic endophyte-infected tall fescue hay (n = 3) or pasture treatment (n = 3) in a crossover design with 14-d periods to estimate DMI with alkane markers and to compare DMI of hay and pasture. When fed pasture, horses were housed in stalls from 0700 to 1300 h daily with access to water and then grazed pasture as a group in a single 0.4 ha pasture from 1300 to 0700 h. When fed hay, horses were maintained individually in stalls and given access to hay ad libitum from 1300 to 0700 h. All horses were individually fed 225 g oats twice daily treated with hexatriacontane (C36; external marker) and fecal samples were collected at 0700 and 1900 h on d 10 to 14. Fecal samples were mixed, dried, subsampled, and analyzed for tritriacontane (C33) and hentriacontane (C31) as internal markers and C36 as the external marker using gas chromatography. Estimated hay DMI using either C33 (1.75 kg/100 kg BW) or C31 (1.74 kg/100 kg BW) as internal alkane marker did not differ (P = 0.55) from measured hay DMI (1.70 kg/100 kg BW). Pasture DMI and DM digestibility (DMD) estimated with C31 (2.24 kg/100 kg BW and 53.1 g/100 g DMI) or with C33 (2.34 kg/100 kg BW and 56.2 g/100 g DMI) was greater (P = 0.05) than hay DMI and DMD (1.74 kg/100 kg BW and 44.5 g/100 g DMI). Intake estimated with C33 or C31 did not differ (P = 0.35) during hay or pasture. In conclusion, alkanes can be used to estimate pasture or hay DMI and DMD, and pasture intake exceeded hay intake when offered ad libitum.

Growth, carcass characteristics, and profitability of organic versus conventional dairy beef steers

Bull calves (n=49), born at the University of Minnesota West Central Research and Outreach Center (Morris) between March and May 2011, were used to compare growth measurements and profitability of conventional and organic dairy steers. Calves were assigned to 1 of 3 replicated groups at birth: conventional (CONV; n=16), organic (pasture and concentrate; ORG; n=16), or organic grass only (GRS; n=17), and analysis of variables was on a pen basis. Breed groups of calves were Holstein (HO; n=9); Holsteins (n=11) maintained at 1964 breed average level; crossbreds (n=19) including combinations of HO, Montbéliarde, and Swedish Red; and crossbreds (n=10) including combinations of HO, Jersey, Swedish Red, and Normande. The CONV steers were fed a diet of 80% concentrate and 20% forage. The ORG steers were fed a diet of organic corn, organic corn silage, and at least 30% of their diet consisted of organic pasture during the grazing season. The GRS steers grazed pasture during the grazing season and were fed high-quality hay or hay silage during the nongrazing season. Intakes of a total mixed ration were recorded daily with herd management software. A profit function was defined to include revenues and expenses for beef value, feed intake, pasture intake, health cost, and yardage. The GRS (358.6kg) steers had lesser total gains from birth to slaughter than ORG (429.6kg) and CONV (534.5kg) steers. Furthermore, the GRS (0.61kg/d) steers had lesser average daily gain from birth compared with ORG (0.81kg/d) and CONV (1.1kg/d) steers. The GRS and ORG steers had smaller rib eye area (49.5 and 65.8cm2, respectively) compared with CONV (75.4cm2) steers. For profitability, GRS steers had 43% greater profit than CONV steers due to organic beef price premiums and lower feed costs. On the other hand, ORG steers had substantially less profit than CONV steers. The higher cost of production for the ORG steers is due to the extreme high value of organic corn. The results of the current study illustrate the economic potential of alternative strategies for growing and marketing male offspring of organic dairy cattle in the Midwest.

The deposition of carotenoids and α-tocopherol in hen eggs produced under a combination of sequential feeding and grazing

This experiment was conducted to determine how layer performance and the concentrations of lutein, zeaxanthin, α-tocopherol and β-carotene in the egg yolks of grazing hens would be influenced by sequential feeding of whole wheat and balancer mixed feed. One hundred twenty free-range hens, divided into two groups, were used in the experiment. The experimental treatment group of 60 hens had access to permanent grassland, whereas the control group only had access to a range without grass. The feed dosages were determined according to the metabolisable energy (ME) requirements, calculated based on body weight, the performance of the hens and the air temperature. Compared with the control group, the grazing hens received a 9% lower dose of ME, which included wheat and balancer diet, to ensure pasture intake. Lyophilised permanent pasture contained 128mg/kg dry matter (DM) of lutein, 115mg/kg DM of zeaxanthin, 75mg/kg DM of α-tocopherol and 79mg/kg DM of β-carotene. Grazing by hens, together with sequential feeding of whole wheat and a balancer mixed diet, significantly increased (P<0.001) the egg concentrations of lutein (by 260μg), zeaxanthin (by 174μg), α-tocopherol (by 270μg) and β-carotene (by 2μg) relative to the control group. The colour of the egg yolks of the grazing hens was assigned a Roche Yolk Colour Fan score of 10.3. Grazing, together with sequential feeding, resulted in the production of eggs with increased oxidative stability measured after storage at 18°C for 28 days. This feeding system permitted the production of eggs as functional foods with significantly increased concentrations of carotenoids without compromising the performance of the hens.

Precision of estimating individual feed intake of grazing animals offered low, declining pasture availability

Measurement of intake of individual grazing animals remains one of the fundamental challenges to improving efficiency of livestock production. The use of wireless sensor networks (WSN) shows potential for this purpose and requires benchmark data to underpin the necessary algorithm development. This study aimed to provide benchmark data and enable improved precision in estimating pasture intake when pasture availability is low and declining. Each of 10 Angus steers with a mean liveweight ± s.d. of 326 ± 46 kg was randomly allocated to an individual grazing plot. The plots comprised a monoculture of Italian ryegrass (Lolium multiflorum cv. Surge), with estimated initial pasture biomass availability ≤1100 kg DM/ha, provided at three levels of pasture availability (low, medium and high), achieved by varying plot sizes (0.2, 0.3 and 0.4 ha). Pasture intake was estimated using two pasture disappearance-based techniques (rising-plate meter and capacitance meter) using regression equations of daily pasture biomass estimates over an 11-day pasture intake period, and two chemical marker-based techniques (dosed n-alkanes and chromic oxide). Both pasture disappearance-based techniques showed high variability in estimating pasture biomass, with mean coefficients of variation between repeated-measurements of 28% for the capacitance meter and 44% for the plate meter, although daily biomass measurements over the duration of the study using the two devices were highly correlated (r = 0.82). Mean pasture intake estimates across all four techniques ranged from 3.4 to 10.7 kg DM/day. The estimates of pasture intake differed between techniques but not between biomass availability treatments. Mean of pasture intake estimates made using the plate meter were consistently higher than for the other three techniques. The correlation coefficients between the intake estimates determined using the pasture disappearance-based techniques, and between their rankings, were 0.61 and 0.58, respectively. Intake estimates obtained using pasture disappearance and the chemical marker methods were not correlated apart from between chromic oxide and the plate meter (r = 0.51). Further refinement of these techniques and more studies over a wider range of pasture conditions are needed. It is critical to understand the limits within which each of the pasture intake methodologies will produce reliable results that can then be used as benchmark data for the development of predictive algorithms using WSN.

Pasture intake and milk production of dairy cows grazing annual ryegrass with or without corn silage supplementation

The use of corn silage to supplement grazing dairy cows can improve milk production and nutrient intake when the substitution rate is low. This enhancement occurs by increasing the total DM intake. The hypothesis tested in this study was that increasing corn silage supplementation level of dairy cows grazing annual ryegrass at medium pasture allowance could increase substitution rate and decrease milk production response. Three supplementation levels (0, 4 and 8 kg DM/day) were compared for dairy cows strip-grazing annual ryegrass (Lolium multiflorum cv. Common). The study was arranged as a 3 × 3 Latin square design, repeated three times using nine Holstein lactating cows. The supplement was a 7 : 1 mixture based on the DM of corn silage and soybean meal and was offered individually twice daily after the morning and afternoon milkings. Each treatment group of cows grazed separately at a common daily pasture allowance of 35 kg DM/cow to ground level. Each experimental period was 12 days, with an 8-day adaptation and a 4-day measurement period. The individual pasture intake was measured from Day 9 to Day 12 using the n-alkane technique. The daily pattern of grazing and ruminating times were measured by visual observations. The supplement DM intake was lower than expected, averaging 3.0 and 4.3 kg DM/day for cows receiving 4 and 8 kg DM/day, respectively. Pasture and supplement energy value were 7.0 and 6.3 MJ of NEL/kg DM, respectively. The substitution rate averaged 0.2 and was unaffected by the supplementation level. The pasture intake was similar for all treatments (14.0 kg of DM/day), and total DM intake and milk production (+0.5 kg of milk/kg DM of supplement) increased linearly with increasing supplementation level. The daily grazing time was shorter by 111 min/day for the supplemented cows than for the unsupplemented cows. Cows grazing the annual ryegrass at medium pasture allowance improved their total DM intake and individual performance when supplemented with corn silage.