Pasture Allowance Research Articles

Impact of pasture feeding cows and seasonality on the concentration of selected fat-soluble compounds in milk and their ability to be used as biomarkers of “Grass-Fed” dairy

This study investigated the impact of proportion of pasture in the cow diet on the concentration of selected fat-soluble compounds in milk including β-carotene, lutein, retinol (vitamin A), α-tocopherol (vitamin E) and zeaxanthin. Bulk tank milk samples (n = 102) were collected weekly (n = 34) across an entire lactation from three herds operating either a high (GRS), medium (PMR) or no pasture allowance (TMR) feeding system. Concentrations of β-carotene and lutein increased significantly with increasing pasture allowance, with a > 2 fold increase of β-carotene in milk, between high and no pasture allowance treatments. GRS feeding system resulted in milks with higher concentrations of retinol, α-tocopherol, and zeaxanthin, compared to both PMR and TMR systems. A biomarker model based on the fat-soluble compounds concentration in milk, demonstrated excellent differentiation of high pasture allowance derived milks from that of medium and no pasture milks, with area under the curve scores of 0.955 and 0.971 respectively. Strong correlations were observed between the concentrations of lutein and zeaxanthin in milk and the milks corresponding yellow colour, while a significant correlation was exhibited between β-carotene and b*-value. Such correlations with milk colour may have a significant impact on the consumer preference of milk and dairy products produced therefrom.

The impact of seasonal calving systems with varying pasture allowance on Cheddar cheese composition, nutritional quality and ripening characteristics

The objective of this study was to examine the impact of stage of lactation (early, mid and late) and proportion of pasture in the cows diet (high: GRS, medium: PMR and no: TMR) on the composition and quality of Cheddar cheese. Triplicate trials were carried out in each stage of lactation, and milk protein and fat contents were standardized for Cheddar cheese manufacture at pilot scale. As cheese milks were standardized for milk fat and protein contents, gross composition did not differ as a result of diet. Fatty acid profiles of GRS cheese were significantly different from TMR, while PMR profiles were less distinct and more similar to both GRS and TMR profiles, as illustrated by partial least squares discriminatory analysis. Fatty acids including CLA C18:2 cis-9, trans-11, C22:1 n-9 and C18:3 n-3 were most influential in this separation of profiles. Fatty acid profiling revealed that GRS derived cheese contained higher proportions of nutrients considered beneficial for human health including higher proportions of unsaturated fatty acids and omega-3 fatty acids. A biomarker model utilizing the proportions of 5 fatty acids was constructed and was effective at distinguishing between cheese of GRS, TMR and PMR feeding systems. Proportions of ρ-κ-casein, αs2-casein and αs1-casein in cheese also differed between diets while proportions of ρ-κ-casein, αs1-casein and β-casein were lowest in late lactation cheese. The impact of diet was less influential compared with that of stage of lactation on the ripening characteristics of cheese. An index of primary proteolysis was highest in late lactation cheese. The peptides derived from the proteolysis of κ-casein and β-casein and levels of secondary proteolysis, in particular, the proportions of 12 free amino acids were most influenced by stage of lactation. Overall this study demonstrated the effects of increasing pasture allowance and stage of lactation on the nutritional quality and ripening properties of Cheddar cheese.

Effect of gestational naural pasture allowance on muscle development of lambs

To study the effects of gestational undernutrition induced by a lower natural pasture allowance on myogenesis and meat production in lambs, two experiments were carried out. In the first, Corriedale sheep were fed contrasting natural pasture allowances (23 days before conception until gestation day 122) and myogenesis was evaluated in 70-day-old fetuses and newborns. In the second, similar ewes were fed with contrasting natural pasture allowances (day 30 of gestation until parturition) and the productive performance, quantity and quality of meat and muscular characteristics in 200-day-old lambs were evaluated. A lower pasture allownace affected fetal myogenesis (fewer secondary fibers) and was associated with reduced mitotic and myoblastic fusion activity in some muscles. In newborns, maternal undernutrition affected muscle histology, fibrillar biological and contractile properties (MyHC-I and GLUT-4). Likewise, undernutrition strongly reduced muscle IGF-1 and could compromise neonatal hypertrophic compensation. On the other hand, maternal undernutrition from day 30 to parturition affected growth, carcass quality and muscle weights at 200 days, although these effects were mainly sex-dependent, with males being the most affected. Maternal undernutrition affected fibrillar composition (greater oxidative activity) in all muscles at 200 days. Biochemical and meat quality characteristics were also affected, although these effects depended on both muscle and sex. In summary, a lower gestational pasture allowance negatively affected fetal myogenesis and neonatal muscle characteristics (worse hypertrophic capacities), and induced fetal programming effects on muscle mass and muscle characteristics at 200 days. This implies that, regardless of postnatal conditions, intrauterine alterations induce muscular changes, which may be related to the ability to grow and the quality of the meat produced. Likewise, our results highlight the importance of considering the sex of the animal and the muscle when studying these effects.

Stress response to social isolation followed by exposure to a novel object in aged ewes born to undernourished mothers

Fetal programming by subnutrition affects offspring’s behaviour, metabolism, and sensitivity to stressors in sheep. The objective was to determine the stress response of ewes born to mothers nutritionally restricted during gestation to social isolation followed by exposure to a novel object. Twenty-six-year-old Corriedale ewes born to mothers who grazed high or low pasture allowances (HPA and LPA groups) from 23 days before conception until 122 days of gestation were used. Ewes were individually isolated in a novel place for 10 min, and 5 min after its beginning, an orange ball was dropped into the test pen. The ewes’ behaviours were recorded during the test. Blood proteins, glucose and cortisol concentrations, heart and respiratory rates and rectal and surface temperatures were determined. The number of times looking at the ball tended to be greater in HPA ewes than LPA (6.7 ± 1.0 vs 4.7 ± 0.8, P = 0.08). The LPA ewes had greater serum albumin concentration than HPA ewes (3.2 ± 0.1 g/dL vs 3.0 ± 0.1 g/dL, P = 0.02), regardless of the applied stressors. Overall, the nutritional treatments applied to ewes during their intrauterine development did not modify the stress responses to social isolation followed by exposure to a novel object.

Pasture feeding improves the nutritional, textural, and techno-functional characteristics of butter

There is an increasing consumer desire for pasture-derived dairy products, as outdoor pasture-based feeding systems are perceived as a natural environment for animals. Despite this, the number of grazing animals globally has declined as a result of the higher milk yields achieved by indoor TMR feeding systems, in addition to the changing climatic conditions and lower grazing knowledge and infrastructure. This has led to the development of pasture-fed standards, stipulating the necessity of pasture and its minimum requirements as the primary feed source for products advertising such claims, with various requirements depending on the region for which it was produced. This work investigates the differences in the composition and techno-functional properties of butters produced from high, medium and no pasture allowance diets during early, mid, and late lactation. Butters were produced using milks collected from 3 feeding systems: outdoor pasture grazing (high pasture allowance); indoor TMR (no pasture allowance); and a partial mixed ration (medium pasture allowance) system, which involved outdoor pasture grazing during the day and indoor TMR feeding at night. Butters were manufactured during early, mid, and late lactation. Creams derived from TMR feeding systems exhibited the highest milk fat globule size. The fatty acid profiles of butters also differed significantly as a function of diet and could be readily discriminated by partial least squares analysis. The most important fatty acids in such an analysis, as indicated by their highest variable importance projection scores, were CLA C18:2 cis-9,trans-11 (rumenic acid), C16:1n-7 trans (trans-palmitoleic acid), C18:1 trans (elaidic acid), C18:3n-3 (α-linolenic acid), and C18:2n-6 (linoleic acid). Increasing pasture allowances resulted in reduced crystallization temperatures and hardness of butters and concurrently increasing the "yellow" color. Yellow color was strongly correlated with Raman peaks commonly associated with carotenoids. The milk fat globule size of cream decreased with advancing stage of lactation and churning time of cream was lowest in early lactation. Differences in the fatty acid and triglyceride contents of butter as a result of lactation and dietary effects demonstrated significant correlations with the hardness, rheological, melting, and crystallization profiles of the butters. This work highlighted the improved nutritional profile and functional properties of butter with increasing dietary pasture allowance, primarily as a result of increasing proportions of unsaturated fatty acids. Biomarkers of pasture feeding (response in milk proportionate to the pasture allowance) associated with the pasture-fed status of butters were also identified as a result of the significant changes in the fatty acid profile with increasing pasture allowance. This was achieved through the use of 3 authentic feeding systems with varying pasture allowances, commonly operated by farmers around the world and conducted across 3 stages of lactation.

Maternal undernutrition induced by a lower natural pasture allowance affects muscle characteristics in newborn lambs

We evaluated the effects of differential levels of maternal nutrition induced by contrasting natural pasture allowances (days −23 to 122 of gestation) on newborn lamb’s muscle characteristics. Multiparous ewes were assigned to two nutritional treatments: High-pasture-allowance (HPA) ewes grazed on natural grasslands at 10–12 kg of dry matter (DM)/100 kg of BW/day; and Low-pasture-allowance (LPA) ewes grazed on 5–8 kg of DM/100 kg of BW/day. Samples (Semitendinosus and Longissimus lumborum) were collected from eighteen (9/treatment) male newborn lambs. LPA treatment reduced fiber diameter, nuclei number/fiber and muscle tissue proportion (P ≤ 0.0002) and tended to reduce fiber density (P = 0.097) in the studied muscles. A lower maternal pasture allowance reduced DNA concentration and increased protein/DNA ratio in both muscles (P ≤ 0.002). LPA treatment reduced (P = 0.046) protein concentration in the Semitendinosus. Muscles from LPA lambs showed greater mRNA expressions of MyHC-I and PAX7 (P ≤ 0.014), lower mRNA expression of IGF1 (P = 0.008) and tended to show increased mRNA expression of GLUT-4 (P = 0.09). The Longissimus from LPA lambs showed higher mRNA expressions of GLUT-4 (P = 0.032). Our results demonstrate that a reduced gestational pasture allowance induces several negative effects that might seriously limit postnatal muscle growth. Although LPA muscles showed some insights which could indicate an attempt to compensate for the negative effects (greater GLUT-4 and PAX7 expressions), the local endocrine (autocrine-paracrine) environment (reduced IGF1 expression) could be a major limiting factor for such compensation. Thus, a lower maternal pasture allowance affects newborn lambs muscle characteristics with possible future effects over animal health and meat-producing performance.

Impact of varying levels of pasture allowance on the nutritional quality and functionality of milk throughout lactation

The objective of this study was to examine the impact of increasing proportions of grazed pasture in the diet on the composition, quality, and functionality of bovine milk across a full lactation. Fifty-four spring-calving cows were randomly assigned to 1 of 3 groups (n = 18), blocked on the basis of mean calving date (February 15, 2020 ± 0.8 d), pre-experimental daily milk yield (24.70 ± 3.70 kg), milk solids yield (2.30 ± 0.27 kg), lactation number (3.10 ± 0.13), and economic breeding index (182 ± 19). Raw milk samples were obtained weekly from each group between March and November 2020. Group 1 (GRS) consumed perennial ryegrass and was supplemented with 5% concentrates (dry matter basis); group 2 was maintained indoors and consumed a total mixed ration (TMR) diet consisting of maize silage, grass silage, and concentrates; and group 3 consumed a partial mixed ration diet (PMR), rotating between perennial ryegrass during the day and indoor TMR feeding at night. Raw milk samples consisted of a pooled morning and evening milking and were analyzed for gross composition, free amino acids, fatty acid composition, heat coagulation time, color, fat globule size, and pH. The TMR milks had a significantly higher total solids, lactose, protein, and whey protein as a proportion of protein content compared with both GRS and PMR milks. The GRS milks demonstrated a significantly lower somatic cell count (SCC), but a significantly higher pH and b*-value than both TMR and PMR milks. The PMR milks exhibited significantly lower total solids and fat content, but also demonstrated significantly higher SCC and total free amino acid content compared with GRS and TMR. Partial least squares discriminant analysis of fatty acid profiles displayed a distinct separation between GRS and TMR samples, while PMR displayed an overlap between both GRS and TMR groupings. Variable importance in projection analysis identified conjugated linoleic acid cis-9,trans-11, C18:2n-6 cis, C18:3n-3, C11:0, and C18:2n-6 trans as the largest contributors to the variation between the diets. Milk fats derived from GRS diets exhibited the highest proportion of unsaturated fats and higher unsaturation, health-promoting, and desaturase indices. The lowest proportions of saturated fats and the lowest atherogenic index were also exhibited by GRS-derived milk fats. This work highlights the positive influence of grass-fed milk for human consumption through its more nutritionally beneficial fatty acid profile, despite the highest milk solid percentages derived from TMR feeding systems. Furthermore, this study demonstrates the proportional response of previously highlighted biomarkers of pasture feeding to the proportion of pasture in the cow's diet.

Thermoregulatory, metabolic and stress responses to spring shearing of aged ewes born to undernourished mothers

Maternal undernutrition during gestation affects the behaviour, metabolism, and sensitivity to stressors of the offspring. Shearing is a stressor that triggers physiological and behavioural changes and augments the thermoregulatory demands in sheep. The aim of this study was to compare the thermoregulatory, metabolic, and behavioural responses to spring shearing of aged ewes born to mothers who grazed different pasture allowances during gestation. Nineteen non-gestating six-year-old Corriedale ewes born to mothers who grazed two pasture allowances from 23 days before conception until 122 days of gestation were used. The pasture allowance offered to the mothers was high [HPA group; n = 11; 10–12 kg of dry matter (DM)/100 kg of body weight (BW)/day] or low [LPA group: n = 8; 5–8 kg of DM/100 kg of BW/day]. The adult offspring of both experimental groups were sheared during spring (Day 0), and remained outdoors, grazing natural grassland, and the behaviour, the surface temperature and the rectal temperature were recorded. Blood concentrations of albumin, total protein, glucose, and insulin were also determined. Data were compared with a mixed model. The LPA ewes had lower ear and nose maximum and minimum surface temperatures before shearing (P < 0.05). On Day 15, the average surface temperature of the vulva was lower in LPA than in HPA ewes (P < 0.05). After shearing, rumination frequency was greater in HPA than in LPA ewes (P = 0.01), and LPA ewes were observed more time standing up than HPA ewes (P < 0.0001). Insulin concentration tended to be greater in LPA than HPA ewes (P = 0.06). Maternal undernutrition during gestation modified the thermoregulatory responses and the acute behavioural changes after shearing in aged female offspring, whilst the metabolism was affected to a lesser degree. The long-term effects noticed in this study highlight the importance of providing proper nutrition to pregnant ewes.

Kernel density estimation analyses based on a low power GPS for monitoring environmental issues of grazing cattle

The use of wearable sensors that record animal activity in intensive livestock systems has become more and more frequent for both early detection of diseases and improving quality of production. Their application may be also significant in extensive livestock systems, where there is an infrequent farmer-to-animal contact. The aim of the present study was to prove the feasibility of a novel automatic system for locating and tracking cows in extensive livestock systems based on space-time data provided by a low power global positioning system (LP-GPS). The information was used to study the pasture exploitation by the herd for modelling the environmental impacts of extensive livestock systems, trough Geographical Information Systems. A customized device, placed within a rectangular PVC case compatible with the collar usually worn by animals, was equipped with a LP-GPS omnidirectional system, an integrated SigFox communication system and a power supply. The experimental trial was carried out in an existing semi-natural pasture characterized by good pasture allowance and cultivated grazing areas. Ten cows were embedded with LP-GPS collars and the data, i.e., geographical coordinates and the time intervals related to each cow detection, were recorded every 20 minutes. Data were collected through a specifically developed AppWeb to be further imported and elaborated by using a GIS software tool. In GIS environment, the daily distances travelled by each cow were linked with Heatmaps obtained by applying Kernel Density Estimation models from the points obtained from the LP-GPS collars. The results of the study made it possible to obtain information on some relevant aspects for livestock’s environmental issues. In detail, it was possible to acquire information on herd behaviour related to the use of the pasture, e.g., the area of the pasture most frequently used during the day, individual use of the pasture, possible animal interactions. These results represent a first step towards further insights and research activities because monitoring of animal locations could allow the reduction of several environmental issues such as soil degradation and greenhouses emissions.

Assessment of RumiWatch noseband sensors for the quantification of ingestive behaviors of dairy cows at grazing or fed in stalls

The RumiWatch System (Itin+Hoch GmbH, Liestal, Switzerland) is a sensor system that enables quantification of ingestive behaviors of cattle that may be useful, amongst other things, for estimating dry matter intake. There are currently multiple versions of the RumiWatch Converter software used to convert the recorded data into specific animal behaviors through the use of algorithms. The objective of this research was to evaluate the use of RumiWatch System noseband sensors for quantifying the number of prehension bites and mastication chews in grazing and stall-fed dairy cows using RumiWatch Converter software versions 0.7.3.36 (RWC36) and 0.7.4.13 (RWC13). Two experiments using lactating Holstein-Friesian dairy cattle were conducted. In Experiment I, ten cows grazed perennial ryegrass pasture (Lolium perenne L.) in individual plots that measured 35 m2, with a pasture mass of 2500 kg DM/ha and pasture allowance of 28 kg DM/d. In Experiment II, 14 cows were offered 16 kg DM/d of perennial ryegrass pasture silage in individual indoor feed stalls. In both experiments, ingestive behaviors were quantified with the jaw movement halters and through visual observation using video recordings. The performance of the RumiWatch Converter software was evaluated through Lin’s concordance correlation coefficients with video observation. For grazing cows, there was greater concordance between the RumiWatch System and video observation for the number of prehension bites (0.94 for RWC36 and 0.75 for RWC13) than for the number of mastication chews (0.20 for RWC36 and 0.14 for RWC13). In cows fed in stalls, there was also greater concordance for the number of prehension bites (0.54 for RWC36 and 0.64 for RWC13) than for the number of mastication chews (0.46 for RWC36 and 0.58 for RWC13). However, the RWC36 was more accurate for quantifying feeding behaviors of grazing cows than the RWC13, while for stall fed cows the reverse was true. Overall, both RumiWatch Converters were better at quantifying prehension bites in grazing cows than in stall fed cows, but better at quantifying mastication chews in stall fed cows than grazing cows. These data enable a new understanding of the how these RumiWatch sensors should best be used for measuring cows' feeding behaviors in different feeding systems.

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.

Evaluation of pasture allowance of manganese for ruminants.

The aim of this study was to access the Mn contamination in soil, forages, and animals. Heavy metal pollution is a matter of prime significance in natural environment. Through food chain, toxicity of heavy metals and their bioaccumulation potential are transferred into humans. Higher concentrations of metallic compounds are toxic to living organisms but these are essential to maintain body metabolism. Intake of food crops polluted with heavy metals is chief food chain channel for human exposure. Animals are exposed to heavy metal stress by the intake of richly contaminated food crops; those are chief part of food chain. Samples of soil, plant, animal blood, hair, and feces were collected to find contamination through wet digestion process in lab and metal analysis. Different forages were collected to study Mn content that was our major concern in this study. The present findings also emphasized on the assessment of bio-concentration factor (BCF). Other significant indices of mobility and pollution of metal were also calculated, i.e. pollution load index (PLI), daily intake of metal (DIM), health risk index (HRI), and enrichment factor (EF). The experimentation result showed different concentrations of metal in different seasons. The Mn concentration in forages was 20.01-28.29 mg/kg and in soil was 5.27-8.90 mg/kg. Soil samples showed higher level of (PLI) Pollution load index. Bio-concentration of MN was 2.59-4.21 mg/kg. It can be concluded that regular monitoring of the metal is essential to evaluate the contamination status. Mn contents were in the safe limits in soil and plants; however, its toxic level was observed in animals.

Gestational nutrient restriction under extensive grazing conditions: Effects on muscle characteristics and meat quality in heavy lambs

We evaluated maternal undernutrition effects induced by a lower natural pasture allowance (gestation days 30–143) on histological-biochemical and meat traits in muscles Semitendinosus, cranial Gluteobiceps and Supraspinatus from 200-day old male and female lambs. Maternal undernutrition increased oxidative and reduced glycolytic fibers in all muscles (P ≤ 0.01). Maternal undernutrition reduced the diameter of glycolytic fibers in the cranial Gluteobiceps of exclusively female lambs (P = 0.05) and reduced the diameter of oxidative fibers in the Supraspinatus of exclusively male lambs (P = 0.02). Maternal undernutrition increased lipid content in the Supraspinatus of females (P = 0.001), reduced lactate content (P = 0.03) and WB shear force (P = 0.02) in the Semitendinosus of females, and increased cooking losses in the Semitendinosus of males (P = 0.0069). In conclusion, gestational nutrient restriction induced fetal programming effects on muscle characteristics of lambs. Moreover, our study demonstrates that maternal undernutrition influences muscle and meat characteristics in a sex and muscle-dependent way.

Greenhouse gas emissions and nitrogen efficiency of dairy cows of divergent economic breeding index under seasonal pasture-based management

Greenhouse gas (GHG) emissions and nitrogen (N) efficiencies were modeled for 2 genetic groups (GG) of Holstein-Friesian cows across 3 contrasting feeding treatments (FT). The 2 GG were (1) high economic breeding index (EBI) animals representative of the top 5% of cows nationally (elite) and (2) EBI representative of the national average (NA). The FT represented (1) generous feeding of pasture, (2) a slight restriction in pasture allowance, and (3) a high-concentrate feeding system with adequate pasture allowance. Greenhouse gas and N balance models were parameterized using outputs generated from the Moorepark Dairy Systems model, a stochastic budgetary simulation model, having integrated biological data pertaining to the 6 scenarios (2 GG × 3 FT) obtained from a 4-yr experiment conducted between 2013 and 2016. On a per hectare basis, total system GHG emissions were similar for both elite and NA across the 3 FT. Per unit of product, however, the elite group had 10% and 11% lower GHG emissions per kilogram of fat- and protein-corrected milk and per kilogram of milk solids (MSO; fat + protein kg), respectively, compared with the NA across the 3 FT. The FT incorporating high concentrate supplementation had greater absolute GHG emissions per hectare as well as GHG per kilogram of fat- and protein-corrected milk and MSO. The elite group had a slightly superior N use efficiency (N output/N input) and lower N surplus (N input - N output) compared with the NA group. The high concentrate FT had an inferior N use efficiency and a higher N surplus. The results of the current study demonstrate that breeding for increased EBI will lead to a general improvement in GHG emissions per unit of product as well as improved N efficiency. The results also illustrate that reducing concentrate supplementation will reduce GHG emissions, GHG emissions intensity, while improving N efficiency in the context of pasture-based dairy production.

PSVIII-32 Late-Breaking Abstract: The effect of outdoor stocking density and weather on the behavior of broiler chickens raised in mobile shelters on pasture

Abstract The aim of this study was to examine the behavior, and the relationship between weather and behavior, of broilers raised in mobile shelters with two stocking densities of pasture access. Fifty straight-run Freedom Rangers were used in three replicates (n = 150) at the University of Minnesota West Central Research and Outreach Center (Morris, MN). From 4 to 11 weeks of age, birds were housed in a mobile shelter divided into two equal-sized pens with daily access to pasture. Birds were allocated to one of the two pens corresponding to the treatment groups: 1) high (0.46 m2 per bird) and 2) low (2.5 m2 per bird) density outdoor pasture allowance. Ten focal birds per pen were randomly designated for behavior observations performed eight times weekly from 5 to 10 weeks of age. Counts of the number of birds outside were recorded during each observation. Behaviors were recorded continuously for 1-minute durations (Animal Behaviour Pro© app) on each focal bird. The means averaged for each observation were analyzed in linear mixed models with fixed (treatment), random (pen and replicate), and repeated (observation) effects. Models included age, heat index, solar radiation, and their interactions with treatment based on a backward stepwise selection. The temperature range recorded during the study was 7 to 32 ⁰C. No behavioral differences between treatments were observed. Standing decreased (P &amp;lt; 0.05) as heat index increased. Pasture use declined (P &amp;lt; 0.05) when heat index was greater than 26 ⁰C. Foraging decreased (P &amp;lt; 0.05) and pasture use increased (P &amp;lt; 0.05) as age increased. The results of this study indicate similar behaviors of broilers raised with two levels of pasture allowance and suggests that hot weather negatively affects the use of pasture space. Thus, providing shade in pasture might be a method to increasing ranging in broilers.

Pasture allowance and duration: the effect of restriction on dry-matter intake, energy balance and indicators of metabolic health in early lactation dairy cows

Context Pasture allowance (PA) in early lactation is widely acknowledged to influence animal performance; however, climatic factors can limit grass growth in early spring, resulting in potential feed deficits on farm. Aim The present study determined whether PA restrictions imposed in early lactation impair energy balance and metabolic health of the cow. Methods One hundred and five cows were assigned to one of seven grazing treatments from 14 March to 4 July 2016 (16 weeks). The control-treatment cows were offered a PA to achieve a post-grazing sward height of 3.5 cm. The cows on the remaining treatments were offered a PA representing 60% of that offered to the control cows for a duration of 2 or 6 weeks from 14 March (mid-March; MMx2 and MMx6), 28 March (end-March; EMx2 and EMx6) or 11 April (mid-April; MAx2 and MAx6). Measurements were collected over the final 2-week period of the restriction for each individual restricted treatment and the control treatment. Key results Restricting PA in early lactation (34–88 days in milk) resulted in a mean reduction in dry-matter intake (DMI) of 25%; however, DMI as a proportion of the control treatment declined for EMx6 (75% of control DMI achieved) and MAx6 (65%) compared with the MMx6 (78%), which may be attributable to changes in the sward, as the plant changes from the vegetative to reproductive phase during this period. The reduction in milk production, relative to the control treatment, was similar among all restricted treatments (18%), resulting in a 1.1-kg reduction in milk output per 1-kg reduction in DMI. However, there was no effect of PA restriction or duration on body condition score, energy balance or blood metabolites, suggesting that the animals used in the current study made sufficient physiological adaptions to partition energy for the maintenance of body reserves. Conclusion In conclusion, short-term restrictions of PA up to 25% of DMI, for up to 6 weeks, can be used as a management strategy to cope with feed deficits in early lactation without impairing normal metabolic function of the early lactation dairy cow. Implications The results of the present study identified the ability of the early lactation dairy cow at grass to adapt to short-term deficits in pasture availability, without affecting the metabolic functioning of the animals

Maternal undernutrition affects secondary myogenesis in a muscle-dependent way across the major muscles of 70-day old ovine fetuses

Abstract The present study evaluated the effects of maternal undernutrition induced by a lower natural pasture allowance from 23 days before conception on the distribution and morphometry of muscle precursor cells and the expression of PCNA, Myogenin and Pax 7 in muscles Psoas major, Longissimus lumborum, Semitendinosus, Semimembranosus, Gluteobiceps and Gluteus medius of 70-day old sheep fetuses. Ewes were assigned to two nutritional treatments (complete randomized block design) beginning 23 days before conception: High pasture allowance (HPA) ewes grazed on natural grasslands at 10−12 kg dry matter (DM) /100 kg of live weight (LW)/day, while low pasture allowance (LPA) ewes grazed at 5−8 kg DM /100 kg of LW/day. On day 70 of pregnancy 18 ewes (nine/treatment) carrying single male fetuses were euthanized and samples were taken from fetal muscles. Samples were stained with hematoxylin-eosin to evaluate muscle morphology and treated with immunohistochemical methods to evaluate the expression of myogenic regulatory factors. Maternal undernutrition reduced the ratio of secondary to primary fibers (P

Hepatic one-carbon metabolism enzyme activities and intermediate metabolites are altered by prepartum body condition score and plane of nutrition in grazing Holstein dairy cows

Precalving feeding level and body condition score (BCS) alter postcalving energy balance and oxidant status of dairy cows. We hypothesized that the reported benefits of a controlled restriction precalving depend on precalving BCS. The objective was to identify alterations in activity and intermediates of the hepatic one-carbon metabolism, transsulfuration, and tricarboxylic acid pathways. Twenty-eight pregnant and nonlactating grazing dairy cows of mixed age and breed (Friesian, Friesian × Jersey) were randomly allocated to 1 of 4 treatment groups in a 2 × 2 factorial design: 2 prepartum BCS categories [4.0 (thin, BCS4) and 5.0 (optimal, BCS5); 10-point scale], by managing cows in late lactation to achieve the 2 groups at dry-off, and 2 levels of energy intake during the 3 wk preceding calving (75 or 125% of estimated requirements), obtained via allowance (m2/cow) of fresh pasture composed of mostly perennial ryegrass and white cover. Average (± standard deviation) age was 6 ± 2, 6 ± 3, 5 ± 1, and 7 ± 3 yr for BCS4 fed 75 and 125%, and BCS5 fed 75 and 125%, respectively. Breed distribution (average ± standard deviation) for the 4 groups was 79 ± 21, 92 ± 11, 87 ± 31, and 74 ± 23% Friesian, and 17 ± 20, 8 ± 11, 13 ± 31, and 25 ± 23% Jersey. Liver tissue was collected by biopsy at -7, 7, and 28 d relative to calving. Tissue was used for 14C radio-labeling assays to measure betaine-homocysteine S-methyltransferase, 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR), and cystathionine-β-synthase (CBS) activity. Liver metabolomics was undertaken using a targeted liquid chromatography with tandem mass spectrometry-based profiling approach. After initial liquid chromatography separation, mass spectra were acquired under both positive and negative ionization, whereas multiple reaction monitoring was used to measure target compound signal response (peak area count). Enzyme activity and metabolite peak area count were normalized with the homogenate protein concentration. Repeated measures analysis of variance via PROC MIXED in SAS (SAS Institute Inc., Cary, NC), with BCS, feeding, and time as fixed effects, and cow as random effect was used. All enzyme activities were affected by time, with betaine-homocysteine S-methyltransferase activity peaking at 7 d, whereas CBS and MTR activity decreased postpartum. Overall, thin cows had greater MTR activity, whereas cows fed 125% requirements had greater CBS activity. An interaction was detected between BCS and feeding for CBS activity, as thin cows fed 125% of requirements had greater overall activity. Compared with liver from BCS4 cows, BCS5 cows had overall greater betaine, glycine, butyrobetaine/acetylcholine, serine, and taurine concentrations. The same metabolites, plus choline and N-N-dimethylglycine, were overall greater in liver of cows fed 75% compared with those fed 125% of requirements. An interaction of BCS and feeding level was detected for the aforementioned metabolites plus methionine, cystathionine, cysteinesulfinate, and hypotaurine, due to greater overall concentrations in BCS5 cows fed 75% of requirements compared with other groups. Overall, differences in hepatic enzyme activity and intermediate metabolites suggest that both BCS and feeding level can alter the internal antioxidant system (e.g., glutathione and taurine) throughout the periparturient period. Further studies are needed to better understand potential mechanisms involved.

Intake, milk production and grazing behaviour responses of strip-grazing dairy goats to daily access time to pasture and to dehydrated lucerne supplementation

The ability of grazing dairy goats to adapt to short daily access time to pasture is not well known, while, in practice, access time to pasture (AT) is often lower than 12 h/d. A 3-week trial was carried out in spring with 36 Alpine dairy goats in mid-lactation to study the effect of a restriction of access time to pasture, coupled or not with a dehydrated lucerne supplement. Three treatments were compared: (1) 7 h/d of access time to pasture, between milkings, without dehydrated lucerne (namely AT7); (2) 7 h/d of access time to pasture, between milkings, with 371 g DM/d of dehydrated lucerne, distributed individually after evening milking (namely AT7D); and (3) 11 h/d of access time to pasture, 7 h/d between milkings plus 4 h/d after evening milking, without dehydrated lucerne (namely AT11). The daily pasture allowance was 2.3 kg DM/goat at 4 cm above ground level in each treatment. Each goat received 602 g DM/d of a commercial concentrate, given twice daily at milking. Pasture intake decreased by 433 g DM/d (i.e. 18%) between AT11 and AT7 (P<0.01). Pasture intake also decreased by 259 g DM/d between AT7 and AT7D (P<0.01), which means a substitution rate of 0.72 between pasture and dehydrated lucerne. Milk production, and milk fat and protein concentrations were not affected by AT (P>0.10). Milk production response to dehydrated lucerne was 0.82 kg of milk/kg DM. Grazing time decreased by 2.5 h/d between AT11 and AT7 or AT7D (P<0.001). The pasture intake rate averaged 272 g DM/h and tended to increase between AT11 and AT7 (P = 0.08). It is concluded that an access time to pasture of 7 h/d may be sufficient for lactating dairy goats receiving 600 g/d of concentrate and grazing high-quality pastures. Supplying 400 g/d of dehydrated lucerne has a much stronger positive effect on milk production than an additional grazing period of 4 h after evening milking.

Pasture allowance, duration, and stage of lactation—Effects on early and total lactation animal performance

Pasture availability in early spring can be limited due to climatic effects on grass production, increasing the likelihood of feed deficits in early lactation of spring-calving pasture-based systems. We hypothesized that restricting pasture allowance (PA) when animals are at peak milk production will have more negative implications on milk production compared with restricting animals before this period. A total of 105 cows were assigned to 1 of 7 grazing treatments from March 14 to October 31, 2016 (33 wk). The control treatment was offered a PA to achieve a postgrazing sward height > 3.5 cm and mean pasture allowance of 15.5 kg of dry matter per cow. The remaining treatments were offered a PA representing 60% of that offered to the control for a duration of 2 or 6 wk from March 14 (mid-March; MMx2 and MMx6), March 28 (end of March; EMx2 and EMx6), or April 11 (mid-April; MAx2 and MAx6). Within grazing treatment, animals were also assigned to 1 of 2 calving dates (early and late) based on days in milk (DIM) on March 14. Early calved (EC) cows were ≥36 DIM, while late calved (LC) were ≤35 DIM. Restricting PA for 2 and 6 wk reduced daily milk yield (-1.6 and -2.2 kg/cow, respectively), cumulative milk protein yield (-4.0 and -6.3 kg/cow, respectively), and cumulative milk solids yield (-5.8 and -9.5 kg/cow, respectively) in the first 10 wk of the experiment. Daily milk yield was similar across the treatments at the end of the 33-wk period (16.8 kg/cow, average of all treatments), as was daily milk solids yield (1.40 kg/cow). Cows in the EC group produced less milk over the first 10 wk of the experiment (20.0 kg/cow per day) compared with the LC animals (22.1 kg/cow per day). However, body weight was greater (+15 kg/cow) in the EC animals compared with the LC, while body condition score was similar (2.85). This outcome indicates that animals that are restricted later in early lactation (circa onset of peak milk production) partition a greater proportion of available energy to maintenance, resulting in greater losses in milk production. These data indicate that despite the immediate reduction in milk production, restricting intake of grazing cows to 80% of that required to achieve spring grazing targets for postgrazing sward height for up to 6 wk may be used as a method of managing short-term pasture deficits on farm with minimal effects on total lactation performance.