Pasture Intake Research Articles

The effect of concentrate feeding strategy and dairy cow genotype on milk production, pasture intake, body condition score and metabolic status under restricted grazing conditions

The objective of this study was to compare the effects of contrasting concentrate feeding strategies and dairy cow genotypes on milk production, pasture intake, energy balance, and metabolic status under restricted grazing conditions. Fifty-eight Holstein Friesian cows were assigned to concentrate feeding strategy and genotype treatments in a 2 ˣ 2 factorial arrangement, in a randomized complete block design. Treatments were balanced for days in milk, parity, previous 305-day milk yield, and body condition score (BCS). The dietary treatments offered over the 11-week experimental period were a low flat rate concentrate allowance of 1.76 kg DM/d typical of a low input system (CON, n = 29) or a “feed to yield” concentrate allowance (FY, n = 29). The FY treatment included feeding a base of 1.76 kg DM plus 0.44 kg DM of concentrates/kg of milk above the base milk yield. All cows were allocated 13 kg DM of grass. The genotype treatments consisted of lower fertility higher milk (LFHM) and higher fertility lower milk (HFLM) cows based on Economic Breeding Index figures. The FY strategy resulted in a higher milk (+ 1.77 kg/d) and a higher fat plus protein yield (+ 0.12 kg/d) and increased BCS (+ 0.12 units) compared to CON. The metabolic status of FY cows differed from CON cows as evidenced by the reduced β-hydroxybutyrate and non-esterified fatty acid concentrations. Genotype did not influence milk output but did affect total dry matter intake (DMI) and BCS. Cows of LFHM tended to have higher yields on the FY resulting in increased milk yield of 11% compared to FY-HFLM cows. Cows of HFLM fed CON had greater fat and protein output of 0.5 kg and 0.5 kg, respectively compared to the CON-LFHM. No differences in feed efficiency was observed between treatments. Despite cows originating from a higher output herd, differences in genotype had a significant effect on the response to the concentrate feeding strategies. These observations are important when identifying suitable genotypes or feeding strategies that most suit grazing systems.

Prediction of pasture intake by beef cattle in tropical conditions

Forage intake is the most important factor for beef cattle raised on pasture, as it is the basis of the diet. Thus, knowing the variables that affect this parameter can help supplementation programs. Thus, a meta-analytic study was conducted to develop and evaluate models for the prediction of pasture dry matter intake (DMIpasture) by beef cattle in tropical conditions. Eight hundred four individual observations of DMIpasture were used, taken from 23 studies through analysis of mixed models, including the study as a random effect. To evaluate the accuracy and precision of the new models proposed as well as for the models of Azevedo et al. (2016) and Minson and McDonald (1987), an independent databank with 87 means from treatments of 21 experiments (n = 888 animals) was used. Three prediction models were adjusted: model I (animal information), model II (animal information + supplement), and model III (animal information + supplement + pasture). The proposed models presented similarity for the average square root of the prediction error. The inclusion of the predictive variables for supplementation (supplement dry matter intake - DMIsupplement - % of the body weight and crude protein intake through supplement) with the variables for the animal (BW0.75 and average daily gain) and of the pasture (% of crude protein) in model III improved accuracy and precision and provided higher determination and correlation coefficients, and agreement than the other proposed models. Similarly, it was found to be more accurate and precise than the equations of Azevêdo et al. (2016) and Minson and McDonald (1987), which presented lower precision. The DMIpasture for beef cattle in tropical conditions is more accurate and precise when the information for the animal, supplement, and pasture is included.

Forage intake by heifers on alexander grass (Urochloa plantaginea (Link.) Hitch) fertilized with different levels of nitrogen

This work was conducted to study the efficiency of using nitrogen on Alexander Grass (Urochloa plantaginea (Link.) Hitch) through information about the characteristics of the pasture and forage intake of beef heifers. The experiment was carried out at the Federal University of Santa Maria (Universidade Federal de Santa Maria, UFSM) in Santa Maria, Rio Grande do Sul, Brazil, from January to April of 2014. The treatments consisted of doses of zero, 150, or 300 kg/ ha nitrogen (N) in the form of urea. The study used a rotational pasture method and 16 Angus heifers with a mean initial age and body weight (BW) of 15 months and 276 ± 17.4 kg, respectively. Forage intake was evaluated by treating two picketed test heifers with chromium oxide (Cr2O3) for eleven days as an external indicator of fecal production. The experimental design was completely randomized, and the measurements were repeated over time with three treatments and two repetitions per area. Crude protein content was 3.4% higher under 300 kg/ha nitrogen fertilization compared to 150 kg/ ha (18.7%). Independent of the N application rate, the heifers ingested 2.2 ± 0.09 kg DM 100/ kg BW of forage. Nitrogen fertilization of Alexander grass modified the structure of the pasture, increasing the quality and total production of the forage. Heifers pastured on Alexander grass fertilized with 300 kg/ha nitrogen harvested forage with higher levels of crude protein. The structural change in the canopy let the heifers reduce their consumption of forage at the end of the Alexander grass life cycle.

The timing of pasture allocation and grass silage supplementation affect pasture intake, milk production and nitrogen partitioning of dairy cows

Aim of study: To evaluate the effect of time of pasture allocation (PA) and grass silage allocation on dry matter (DM) intake, grazing behaviour, milk production, rumen function and N partitioning of grazing dairy cows.Area of study: Valdivia, ChileMaterial and methods: Forty-five Holstein-Friesian cows were selected from the Austral Agricultural Research Station at the Universidad Austral de Chile. Cows were allocated to one of three treatments: MPA: 75% of PA and 25% of the silage allowance allocated in the morning; BPA: 50% of PA and silage allowance allocated in the morning; APA: 25% of the PA and 75% of the silage allowance allocated in the morning. All treatments received the complement of pasture and silage allowance in the afternoon. Cows received a daily PA of 21 kg dry DM, 3 kg DM of grass silage and 3.5 kg DM of concentrate.Main results: Grazing time was not affected by treatments, however, grazing time between afternoon-morning milking was longer for APA. DM intake and milk production were not modified by treatments, averaging 15.6 kg DM/cow and 22.7 kg milk/d, respectively. Rumen propionate was greater for BPA than APA (18.8 and 17.7 mmol/100 mol, respectively). N intake and N excretion throughout milk, urine and feces were not modified by treatments, averaging 458, 119, 195 and 144 g N/d, respectively.Research highlights: The combination of time of pasture and grass silage allocation is not an adequate strategy to modify pasture intake, milk production and N excretion in dairy cows.

114. Effect of grazing and feeding management on milk mineral concentrations

Application. Pasture intake and non-Holstein genetics were negatively correlated with milk I, Mn, and Cu, and positively correlated with milk Ca and P; but other feeds and mineral supplementation also influenced milk mineral concentrations. Introduction. Milk is a good source of minerals (Ca, Mg, P and K) and trace elements (I, Se, Zn), which are essential for optimum health [2]. Pasture intake may increase milk Ca and P concentrations but decrease Cu and Se concentrations, although pasture composition, plant maturity, and animal/environmental factors will also have an effect [1]. This study aimed to (i) investigate the milk mineral concentrations in herds with different pasture intakes, and (ii) assess the relative impact of individual feeds. Material and methods. Bulk-tank milk samples (n = 359) were collected monthly (over 12 months) from 30 dairy farms, and animal diet and breed were gathered via questionnaire. Three groups of 10 farms represented contrasting grazing management between April-September: high pasture intake (HP; 28–65% DMI), standard pasture intake (SP; 5–18% DMI), outdoors with low/limited pasture intake (LP; 0–3% DMI). Milk mineral concentrations were determined using ICP-MS. Analysis of variance by linear mixed effects models used pasture intake (HP, SP, LP), months (12 months), and their interaction as fixed factors. Farm ID was used as a random factor. A multivariate redundancy analysis (RDA; CANOCO 5) assessed the relative impact of breed and feeds on milk mineral concentrations. Results. When compared with HP and LP farms, milk from SP farms contained significantly less Ca (−50 mg/kg and −45 mg/kg, respectively) and P (−25 mg/kg and −29 mg/kg, respectively) (Table 1). The RDA indicated that pasture intake and non-Holstein genetics were negatively correlated with milk I, Mn, and Cu, and positively correlated with milk Ca and P. Grass/grass-clover silage and dry-straights were positively correlated with I, Mn, Cu, Mo, Zn and negatively correlated with Na. Intakes of maize silage, blends, moist by-products, oils and minerals were negatively correlated with Mn, Cu, Mo, Zn, Ca and P. Milk from low/no grazing periods contained, on average, more I (+21.1%), Mn (19.5%), Cu (+16.9%), Zn (+6.1%) and Mo (+5.5%), than milk produced from the grazing season, although between-month differences were not always significant.

EFFECT OF GRAZING TIME ON DIGESTION AND ENERGY UTILIZATION OF GOAT DURING LACTATION PERIOD IN HALAIB-SHALATEEN PASTURES

Thirty lactating Balady goats were employed in a 90-day experiment to study the effect of grazing time on pasture intake, digestion, energy expenditure (EE) and energy balance (EB) throughout early and late lactation periods in Halaib - Shalateen pastures. To achieve this objective, female goats were divided into three treatments, 10 per each; the first treatment (T1) was in-door without grazing and given 1% of live body weight (LBW) concentrates feed mixture (CFM) plus berseem hay ad libitum. The second (T2) and third (T3) treatments were allowed to graze daily on Panicum turgidum as a basal range plant for 4, 8 hours, respectively and given 1% of LBW CFM. The results could be summarized as follows: The forage intake (g/ kg BW0.75) by goats was significantly (P≤0.01) higher in early lactation than that in late lactation period. Goats that grazed for 8 hours daily showed higher (P≤0.01) forage intake than those grazed for 4 hours daily, while, goats fed on berseem hay ad libitum without grazing had higher (P≤0.01) value of roughage intake compared to the two grazed groups whether in the early or late lactation period. Similar findings were observed for nutrients intakes (OM, CP and NDF). Grazed goats for 4 hr and 8 hr had higher (P≤0.01) values of DM, OM, CP, CF, NDF and digested energy (DE) than these in zero-grazing group whether in the early lactation or in the late lactation period. Goats grazed for 8 hr daily had higher (P≤0.01) values of digestible and metabolizable energy intake than those in 4 hr and zero-grazing groups whether in the early or late lactation periods. Grazed goats for 4 hr and 8 hr had higher (P≤0.01) values of heart rate (HR) and energy expenditure (EE) than that in zero-grazing group. The energy balance (EB), when expressed as kJ/kg BW0.75/day, was positive and greater (P≤0.01) for zero-grazing goats than those in grazed groups. Also, 8 hr-grazing group had greater (P≤0.01) value of EB than that 4 hr-grazing group, but it was negative for the two groups. It could be concluded that, under arid-area condition, in Halaib – Shalateen pastures, grazing of goats for 8 hours daily showed better nutritional performance represented by an increase in the pasture intake, digestion, reduction energy expenditure (EE) and therefore, energy balance (EB) was better than that grazing for 4 hours during early and late lactation periods.

Economic assessment of plantain (Plantago lanceolata) uptake in the New Zealand dairy sector

Pasture-based dairy production is associated with nitrogen-leaching losses to water. The New Zealand (NZ) Government has recently focused on regulating these losses through a broad-ranging policy package. Nitrogen (N) limits under this proposed legislation are stringent, dictating that around 40% of dairy farms must reduce their leaching, on average, by 42%. This study employed comprehensive economic models to account for the farm-, sector-, and national-level impacts of different levels of adoption of narrow-leaved plantain (Plantago lanceolata). This alternative forage species holds substantial promise for reducing the risk of N leaching from dairy farms. Model output indicated that total NZ dairy profit was higher each year by 1, 1.6, 2.5, and 4.3% under the policy package if 10, 20, 30, and 45% of pasture intake by dairy cows consisted of plantain, respectively. Further, national economic output increased by $277 m, $396 m, $526 m, and $979 m, under the policy package if 10, 20, 30, and 45% of pasture intake consisted of plantain, respectively. These represent increases in national economic output of 0.08, 0.11, 0.15, and 0.28%. Modelled outcomes emphasise the potential value of plantain, given the scarcity of low-cost mitigation options compatible with NZ dairy systems. Further, they indicate the significant return accruing to investment in further plantain research to aid successful implementation on farm.

346 Sensor-Determined Behaviors and Pasture Intake Estimation in Extensive Grazing Systems

Abstract Wearable sensor devices to monitor livestock behavior and location in extensive grazing systems can overcome limitations to collection and use of behavior data. These data enable generation of new phenotypes for genetic parameter estimation and decision support tools. Technical challenges, including device hardware and location on-animal, sensor types and modalities, data and power management, and sensor networks to enable measurement of livestock phenotypes in extensive environments, are being addressed. Wearable sensors currently used for behavior classifications include accelerometers, magnetometers and/or gyroscope within inertial measurement units, and pressure and acoustic sensors. We primarily use tri-axial accelerometers because of their reliability and richness of data for feature extraction to classify behaviors. Behavior data combined with GPS also allows location, activity and behavior mapping. Development of livestock behavior classifiers using sensors requires annotation of time-synchronized behavior recordings using video and/or a behavior recording app (e.g. CSIRO AnnoLog). Various analytical methods are used to classify behaviors from sensor data, including supervised machine-learning applied to accelerometer data. Our devices generate data for concurrent classification of behaviors including grazing, ruminating, walking, resting and drinking with reliabilities ≥ 90%. Estimates of pasture intake using behavior data across a range of environments also require validation. We have a facility to concurrently generate benchmark estimates of pasture intake using chemical markers and/or biomass disappearance while recording behaviors using sensors. To date, our R&D using pastures ranging from nutritionally optimal to severely drought affected suggest time spent grazing accounts for up to 60% of variation in pasture intake by individual beef cattle. We are assessing other sources of variation including pasture removal events (bites, tears), classes of cattle, and pasture characteristics to determine if more variation in pasture intake can be explained within extensive grazing systems to enhance development of new traits and applications for precision management.

381 Smart Farming for Extensive Grazing Ruminant Production Systems

Abstract Smart farming for extensive grazing systems includes applications linking environment and supply-chain, including metrics for climate, soils, pastures, animals and animal products to enhance management, optimization and predictions. Technological developments for remote monitoring in extensive systems have varied in their success and remain limited in uptake, and include: In-field, fixed-device monitoring of livestock numbers, water, photosynthesis and greenhouse gas emissions; body composition and physiology assessments using devices fixed to handling facilities; ground- or aerial-based livestock, water, pasture, invasive weeds and/or soil monitoring using photogrammetry or technologies including LiDAR; multi-channel, satellite-based spectrometry coupled with weather and soil grids to model and predict pasture biomass components; automated in-field liveweight measurement and drafting; virtual fencing; on- and in-animal devices to monitor location, activity, behaviors and physiology; GPS to monitor asset and personnel location. These technologies target productivity, efficiency, health and welfare of ruminants, including genetic improvement, and more efficient, sustainable resource use, including soils, pastures and water, to improve individual ruminants and grazing systems. We have developed and validated technologies for remote, in-field determination of animal behaviors, pasture characteristics including availability and disappearance mapping for calibration and validation of satellite images, and pasture intake under varying grazing conditions. Examples of our R&D include experimental on-animal sensor devices to classify and monitor behaviors in extensive systems, and development of a GrazingApp linking satellite imagery, weather and soil information to model and predict animal production. Development of these technologies has required analytical methods for big data, including machine learning and artificial intelligence. These and other applications that function in near to real-time are enhanced by management and aggregation of enormous amounts of data generated by sensors and other devices into useful metrics before transmission using wireless networks. These metrics are the basis for data-driven management decisions that reduce risk and enhance profit for grazing enterprises.

163 The effects of energy and lasalocid supplementation on forage intake and energetics of cattle grazing wheat pasture

Abstract Cattle grazing wheat have the potential to gain BW exceptionally well, but excessive nitrogen intake results in increased excretion and increased greenhouse gas (GHG) emissions. Supplemental grain with the addition of an ionophore given to ruminants grazing wheat is a potential practice for producers to increase nitrogen efficiency while decreasing GHG emissions. Therefore, the objective of this experiment was to quantify the effects of energy and lasalocid supplementation on nutrient intake, respiratory gas fluxes, and performance of grazing cattle. Heifers (n = 18) were used in a 49-d experiment that consisted of two 21-d blocks with 7 d between them (initial BW=311±17.3 kg and 339±16.7 kg, Block 1 and 2, respectively). Heifers were assigned randomly to 1 of 3 treatments; no supplement (Control, n = 6), 2.95 kg control feed/d (Energy, n = 6), or 2.95 kg feed with lasalocid/d (Lasalocid, n = 6). Cattle grazed an 8.1-ha paddock of winter wheat and had access to a GreenFeed system used to quantify the respiratory gas fluxes (CH4, CO2, and O2). Cattle were weighed on d 0 and 21 of each block, on d 15 to 21 cattle were gathered every 12 h and fecal samples were collected. Data were analyzed using the PROC MIXED in SAS. Methane emissions were not affected (P = 0.58) by treatment, but supplemented cattle had greater (P = 0.04) CO2 emissions and O2 consumption (P = 0.03). Hence, ADG tended to be greater for supplemented cattle (P = 0.09) compared with Control (1.22 and 1.00 kg, respectively), but no effect (P = 0.88) was observed for the Lasalocid. Fecal output was greater for supplemented cattle (P < 0.01), but forage intake was lower (P < 0.01) and nutrient intake was higher (P < 0.01) for supplemented cattle compared to Control. Supplemented cattle had lower forage intake with greater CO2 emissions and O2 consumption, but the Lasalocid did not affect any parameter.

164 The effects of energy and lasalocid supplementation on forage intake and energetics of cattle grazing wheat pasture

Abstract Cattle grazing wheat have the potential to gain BW exceptionally well, but excessive nitrogen intake results in increased excretion and increased greenhouse gas (GHG) emissions. Supplemental grain with the addition of an ionophore given to ruminants grazing wheat is a potential practice for producers to increase nitrogen efficiency while decreasing GHG emissions. Therefore, the objective of this experiment was to quantify the effects of energy and lasalocid supplementation on nutrient intake, respiratory gas fluxes, and performance of grazing cattle. Heifers (n = 18) were used in a 49-d experiment that consisted of two 21-d blocks with 7 d between them (initial BW=311±17.3 kg and 339±16.7 kg, Block 1 and 2, respectively). Heifers were assigned randomly to 1 of 3 treatments; no supplement (Control, n = 6), 2.95 kg control feed/d (Energy, n = 6), or 2.95 kg feed with lasalocid/d (Lasalocid, n = 6). Cattle grazed an 8.1-ha paddock of winter wheat and had access to a GreenFeed system used to quantify the respiratory gas fluxes (CH4, CO2, and O2). Cattle were weighed on d 0 and 21 of each block, on d 15 to 21 cattle were gathered every 12 h and fecal samples were collected. Data were analyzed using the PROC MIXED in SAS. Methane emissions were not affected (P = 0.58) by treatment, but supplemented cattle had greater (P = 0.04) CO2 emissions and O2 consumption (P = 0.03). Hence, ADG tended to be greater for supplemented cattle (P= 0.09) compared to Control (1.22 and 1.00 kg, respectively); but no effect (P = 0.88) was observed for the Lasalocid. Fecal output was greater for supplemented cattle (P < 0.01), but forage intake was lower (P < 0.01) and nutrient intake was higher (P < 0.01) for supplemented cattle compared to Control. Supplemented cattle had lower forage intake with greater CO2 emissions and O2 consumption, but the Lasalocid did not affect any parameter.

Suplementación de vacas a pastoreo con ensilado de grano húmedo de maíz o concentrado comercial

The effect of supplementation with high-moisture corn grain silage or a commercial concentrate on intake and milk production in dairy cows was evaluated. Forty cows grazing on improved pastures were assigned to five treatments according to a randomized complete block design for 9 weeks: no supplementation, supplementation with 3 or 6 kg (as fed) of high-moisture corn grain silage, supplementation with 3 or 6 kg (as fed) of a commercial concentrate. Although pasture intake decreased with increasing level of supplementation, total nutrient intake was higher. A higher milk, solids yield, and weight gain was observed with increasing level of supplementation. No effect of type of supplement or interaction between these two factors was detected. Supplementation of grazing cows resulted in a better performance, but type of supplement had no relevant effect on the animal´s response.

Effects of grazing muzzles on behavior and physiological stress of individually housed grazing miniature horses

Grazing muzzles are used on obese-prone equids to limit intake of pasture while grazing. However, the length of time grazing muzzles must be worn to prevent weight gain and whether they impede normal grazing behavior to the degree they impact welfare is unknown. The objective of this study was to assess the effects of muzzling for different lengths of time on horse behavior and physiological stress. Six mature miniature horses (initial BW of 230 ± 19.6 kg; BCS 6 ± 0.4) were studied using a 3 × 3 Latin Square repeated measure design with horses receiving one of three treatments over three 21 d periods. Treatments were unmuzzled (M0), muzzled for 10 h (M10, 0830-1830 h), or muzzled for 24 h (M24). Horses were housed in adjacent individual 0.11 ha grass paddocks for 24 h/d. Daily at 0800 h, muzzles were removed, horses were groomed and fed 14 g vitamin and mineral supplement. Muzzles were re-applied at 0830 h. Body morphometrics were assessed at the start and end of each period. Each horse’s willingness to accept muzzle application was measured daily using a 1 (strongly accepts) to 5 (strongly rejects) scale. Horse behavior was monitored twice weekly with video recordings for 1 h each in the morning and afternoon. Physiological stress was assessed weekly using salivary cortisol concentrations (SC), heart rate (HR), and indices of heart rate variability (HRV). Data were analyzed as repeated measures with treatment and wk as main effects. M24 horses lost BW while M0 and M10 horses gained BW over the course of the study (P = 0.01). M24 horses spent more time grazing than M10 horses (P = 0.04). M0 horses spent more time walking than M10 or M24 horses (P = 0.02). M10 horses spent more time resting than M0 or M24 horses (P < 0.01), and a trend was observed where M10 horses spent more time lying down than M24 horses (P = 0.06). There was no effect of treatment on behaviors associated with frustration including pawing and head shaking. There was no effect of treatment on muzzle acceptability score; however, all horses were less accepting of muzzle application by the third wk of each period (P = 0.01). HR was lower and beat-to-beat interval was higher in M24 horses than in M0 horses (P = 0.02, 0.04 respectively). Salivary cortisol concentrations were not different between treatments. Muzzling horses while on pasture for 24 hs a day resulted in a small loss of BW and altered time spent performing behaviors, but no observed impact on our physiological stress measures.

Maximising Lucerne (Medicago sativa) Pasture Intake of Dairy Cows: 2-the Effect of Post-Grazing Pasture Height and Mixed Ration Level.

Simple SummaryPasture allocation has significant effects on grazing intensity, pasture utilisation and dry matter intake in grazing dairy herds. In sub-tropical Australian partial mixed ration (PMR), systems offering lucerne at an ideal pre-grazing pasture height and allocation, that ensures a proportion remains ungrazed, allows cows to selectively graze the top leafy stratum of the sward. When cows are only grazing the top leafy stratum, diet quality and intake is maximised in PMR systems irrespective of the amount of mixed ration offered.The effects of lucerne (Medicago sativa) post-grazing residual pasture height on pasture utilisation (vertical and horizontal), pasture intake and animal production were investigated in a sub-tropical partial mixed ration dairy system. The study took place at the Gatton Research Dairy, Southeast Queensland (−27.552, 152.333), with a 26-day adaptation period followed by two 8-day measurement periods during August and September 2018. A quantity of 30 multiparous Holstein-Friesian dairy cows were offered two levels of mixed ration, 7 and 14 kg dry matter (DM)/cow/day for low and high levels respectively, and five levels of pasture allocation, to achieve decreasing residual pasture heights. Pasture allocations measured from 5 cm above ground level for the low mixed ration groups averaged 12.7, 15.9, 19.8, 35.3 and 49.2 kg DM/cow/day, and for the high mixed ration groups averaged 5.0, 8.3, 10.3, 18.6, and 25.2 kg DM/cow/day, respectively. As pasture allocation decreased, cows were forced to graze further down into the pasture sward, and therefore residual pasture height declined. Total intake (kg DM/cow/day) declined as residual pasture height (expressed as % of the initial height) declined, irrespective of mixed ration level, decreasing by 0.5 kg DM/cow/day for every 10% decrease in residual pasture height. Low total intakes were associated with high non-esterified fatty acid (NEFA) levels in plasma, indicating mobilisation of fat tissue to maintain milk production. In the high allocation treatments, an area of pasture remained ungrazed and cows were only grazing the top leafy stratum where pasture intake rate and intake were highest. Therefore, to maximise intake in sub-tropical partial mixed ration (PMR) systems, lucerne pasture should be allocated so that cows are always grazing the top leafy stratum. This can be achieved by ensuring the pasture around faecal patches remains ungrazed.

Maximizing Lucerne (Medicago sativa) Pasture Intake of Dairy Cows: 1-the Effect of Pre-Grazing Pasture Height and Mixed Ration Level.

The effect of lucerne (Medicago sativa L.) pre-grazing pasture height on pasture intake and milk production was investigated in a sub-tropical partial mixed ration (PMR) dairy system in south-east Queensland, Australia. The experiment involved a 26-day adaptation period followed by an eight-day measurement period during April and May 2018. Twenty-four multiparous Holstein-Friesian dairy cows were offered a mixed ration at either 7 (low) or 14 (high) kg dry matter (DM)/cow/day and allocated pastures at pre-grazing heights ranging from 23 to 39 cm. The targeted pasture intake was 14 and 7 kg DM/cow/day for cows offered the low and high mixed ration allowances respectively, with a total intake target of 21 kg DM/cow/day. Pasture structure did not limit pasture intake as the all groups left at least 12% of the allocated area ungrazed, and therefore could selectively graze pasture. There was no significant difference in intake between mixed ration levels, however intake had a positive linear relationship with pre-grazing pasture height. For every one cm increase in pasture height, intake increased by 0.3 kg DM/cow/day. Using a grazing strategy that ensures the some pasture remains ungrazed and the pre-grazing height of lucerne is approximately 39 cm above ground level will maximise pasture intake in sub-tropical PMR dairy systems.

Variability in subcutaneous fat composition of Iberian pigs reared in free-range conditions in the southwest of the Iberian Peninsula

A total of 80 free-range Iberian pigs reared with acorns and grass in eight different free-range systems (n = 10) in the southwest of the Iberian Peninsula were used to determine the relationship between fatty acid, tocopherol, and neophytadiene subcutaneous fat composition. The pigs were fed extensively for 79.1 ± 9.5 d from 110.9 ± 11.9 kg live weight at the beginning of the final fattening phase to 175.0 ± 15.9 kg slaughtered weight. Quercus suber and Quercus rotundifolia acorns were characterised by a high content of C18:1n-9 (58.3 and 63.1%, respectively) and γ-tocopherol [43.7 and 43.0 mg kg−1 dry matter (DM), respectively], while grass exhibited a high content of C18:3n-3 (42.5%), α-tocopherol (366.5 mg kg−1 DM) and neophytadiene (136.2 relative area units). The C18:1n-9 (54.4%–57.7%) and γ-tocopherol (2.7–4.1 mg kg−1 DM) contents in subcutaneous fat from Iberian pigs differed (p &lt; 0.001) between the free-range systems studied. Pasture intake had a significant effect (p &lt; 0.01) on subcutaneous fat content of C18:3n-3 (0.5%–0.8%), α-tocopherol (7.8–13.1 mg kg−1 DM) and neophytadiene (2.6–6.3 relative area units). However, the results demonstrated no correlations between accumulated levels of these compounds throughout the free-range period. In conclusion, the absence of correlations corroborated the heterogeneity of extensive rearing systems, with variations between years and geographical areas where the Iberian pigs were reared.

Performance, digestibility, microbial protein synthesis, and body composition of Brangus x Zebu steers on tropical pasture receiving supplementation

The use of additional supplement can affect ruminant performance by increasing the animal weight gain and maximizing profits from the activity. Thus, the objective of this study was to evaluate the influence of protein-energy supplementation on microbial synthesis, animal performance, nutrient digestibility, and body composition of Brangus x Zebu steers on pasture. The experiment lasted 160days and included 36 animals divided into two groups; 18 steers received protein-energy supplementation (PES), and the other 18 received non-supplementation (NPES). Individual pasture intake and nutrient digestibility were estimated using the double indicator technique-chromium oxide and lignin in potassium permanganate. Spot urine samples were collected from 36 animals to determine creatinine, allantoin, and uric acid concentrations. All animals were slaughtered at the end of the experiment to evaluate body composition. There was increase in intake (P < 0.001) and dry matter digestibility (P = 0.01); it resulted in higher animal weight gain (P < 0.001) receiving supplementation. However, there was no difference (P > 0.05) in pasture nutrient intake between treatments. Supplementation increased microbial nitrogen (P < 0.001). For body composition, the model identity test that was applied showed no difference (P > 0.05) between the models, so it was adopted a common equation for both treatments. There was no difference (P > 0.05) for body composition between treatments. Therefore, the use of protein-energy supplementation for steers on pasture allowed higher microbial protein synthesis and better utilization of nutrients, which resulted in better animal performance. The use of protein-energy supplementation at 0.6% BW did not alter the carcass composition of Brangus x Zebu steers. However, it recommends protein-energy supplementation in pasture systems during the rainy period or using an irrigation system.

Performance, milk fatty acid composition and behaviour of high‐yielding Holstein dairy cows given a limited grazing period

AbstractThe effects of a limited grazing period on the performance, behaviour and milk composition of high‐yielding dairy cows were examined. A total of 56 Holstein cows yielding 44.7 ± 0.42 kg/day were allocated to one of four treatments in one of two, 4‐week periods. Treatments were as follows: control (C)—cows housed and offered TMR ad libitum; early grazing (EG)—cows grazed for 6 hr after morning milking then housed; delayed grazing (DG)—cows returned to housing for 1 hr after morning milking followed by grazing for 6 hr, then housed; restricted TMR (RT)—cows grazed for 6 hr after morning milking, then housed and fed TMR at 75% of ad libitum. Intake of TMR was highest in cows receiving C, intermediate in EG and DG, and lowest in RT at 26.9, 23.6, 24.7 and 20.3 kg DM/day respectively. Pasture intake was similar in cows receiving EG or DG, but was higher in RT at 2.4, 2.0 and 3.5 kg DM/day respectively. Milk yield was similar between cows receiving C, EG or DG, but lowest in RT at 45.7, 44.2, 44.9 and 41.7 kg/cow, respectively, while milk fat content of C18:3 n‐3 was increased by grazing. Cows in C spent more than 55 min/day longer lying and had three additional lying bouts/day, while lying bouts were shorter than for cows receiving EG, RT or DG. It is concluded that high‐yielding cows can be grazed for 6 hr/day with little impact on performance, provided TMR is available ad libitum when housed.

Nutrient Intake, Excretion and Use Efficiency of Grazing Lactating Herds on Commercial Dairy Farms.

Simple SummaryExcess nutrients on dairy farms can affect soil and animal health and have negative impacts on the environment. More nutrients are usually brought onto farms in animal feed than in fertilizer and, as dairy cows do not efficiently use feed nutrients to produce milk, most consumed nutrients are excreted in dung and urine. Estimating nutrients excreted by cows relies on measuring feed and nutrient intake. However, measuring pasture nutrients consumed by cows that graze on commercial farms is complicated. We modified the ‘Feeding Standards’ approach to estimate daily pasture dry matter and nutrient intake and nutrients excreted using data and samples readily available on commercial dairy farms. These data were collected on five visits in different seasons from 43 grazing system farms located in diverse climatic zones. Although these herds graze daily, the lactating cows only obtained slightly more than half their dry matter intake from pasture. Each day, on average, we estimated that a grazing cow excretes 433 g nitrogen, 61 g phosphorus, 341 g potassium, 44 g sulphur, 92 g calcium and 52 g magnesium on these farms. Using this approach to estimate nutrients excreted by grazing animals on dairy farms can assist farmers improve nutrient distribution and fertilizer requirements.Estimating excreted nutrients is important for farm nutrient management, but seldom occurs on commercial grazing system farms due to difficulties in quantifying pasture intake. Nitrogen (N), phosphorus (P), potassium (K), sulphur (S), calcium (Ca) and magnesium (Mg) intake, excretion and use efficiency of 43 commercial dairy herds grazing pasture were calculated to understand the range in nutrient intake and excretion in these systems. Milk production, feed (grazed and supplement), as well as farm and herd management data were collected quarterly on representative farms located in temperate, arid, subtropical and tropical regions of Australia. Lactating herd sizes on these farms averaged 267 (30 to 1350) cows, with an average daily milk yield of 22 (9 to 36) kg/cow per day and the herds walked from <0.01 to 4 km/day on a variety of terrains. The mean total metabolizable energy (ME) required by cows in the herds was estimated to be 195 (116 to 289) MJ/cow per day. Although these farms are considered grazing systems, feeding strategies ranged from total dependence on pasture to total mixed rations (TMRTMR) and consisted of a wide variety of nutrient and energy contents. Mean pasture dry matter intake (DMI) (9 kg/cow per day, from 0.1 to 22 kg/cow per day) was just over half of total DMI. Dietary concentration of crude protein, P, K, S, Ca and Mg concentrations were, on average, 19%, 0.45%, 2.1%, 0.29%, 0.65%, and 0.3%, respectively, for all herds and, except for N, supplement nutrient concentrations were always more variable than pasture. Approximately 72% and 88% of diets provided greater than recommended P and N intakes, respectively. Calculated mean N, P, K, S, Ca and Mg excretions were 433, 61, 341, 44, 92 and 52 g/cow per day, respectively. Of the farm characteristics examined, residual maximum likelihood (REML) analysis indicated that daily excreted N, P and S were significantly related to per ha milk production, and excreted P, K and Mg were related to percentage of herd DMI provided as supplement. Mean use efficiencies by cows of N, P, K, S, Ca and Mg were 21%, 25%, 9%, 16%, 23% and 4%, respectively. These estimates of nutrient excretion and feed nutrient use efficiencies can be used to improve nutrient management on grazing system commercial dairy farms.

Lamb Fattening Under Intensive Pasture-Based Systems: A Review.

Simple SummaryThe use of fresh high-quality pastures in intensive lamb production systems is considered worldwide as economically advantageous, environmentally friendly, and a promoter of animal welfare. Moreover, it generates a desirable meat composition. However, it is known that the availability of pastures in grazing regions is variable throughout the year, and this makes the maintenance of a stable offer of feeds and production difficult. The combination of high-quality pastures and other feedstuffs is very common in dairy cow grazing systems while, for sheep, there is less information available. The objective of the current review is to discuss this topic in light of published information about intake, digestion, rumen environment and health, performance, and carcass quality and composition.The benefits of pasture-based systems on the fatty acid composition of sheep meat appear to be achievable despite variability in the quality of the pastures. Lambs fed high levels of temperate pastures have an excess of N-ammonia derived from protein degradation. Furthermore, animal performance is highly variable depending on the quality of the pasture at the time of grazing, and high animal performance in these systems appears to be linked to the use of high-quality pastures with high availability, and is possibly added to by the inclusion of concentrates that allow increasing energy intake and a better use of the N in the pasture. The combination of high-quality pastures and total mixed ration offers a good alternative to the inclusion of concentrates in the diet, improving the use of N, and avoiding acidosis problems. However, information to determine the effect of a number of nutritional strategies on meat quality, and the minimum level of pasture intake necessary to achieve the benefits of pastoral systems is still lacking.