Our aim was to evaluate whether increasing soluble carbohydrates in the herbage by changing the time of the grazing session or including Acacia mearnsii tannin in the diet would affect intake, ...digestion, N partitioning, and productive performance of dairy cows fed a diet combining ryegrass herbage with partial total mixed ration (PMR). We hypothesized that both strategies could reduce the concentration of NH3-N in the rumen, reducing urinary N excretion. Nine Holstein cows were used in a triplicate 3 × 3 Latin square experiment with 3 experimental periods of 22 d. The cows were fed a fixed amount of PMR 60% of the predicted individual dry matter intake (DMI), and an unrestricted amount of herbage in 1 grazing session of 5 h/d. The treatments were (1) morning grazing session and afternoon PMR meal (AM); (2) morning PMR meal and afternoon grazing session (PM); and (3) morning grazing session and afternoon PMR meal supplemented with 15.0 g of tannins/kg of PMR dry matter (TAN). Milk production was not affected by treatments. Although the protein concentration was lower for TAN than for PM, no differences were detected for the yield of any component between treatments. The concentration of individual or grouped fatty acids in milk fat was not affected by treatments, except for 16:1 cis-9 and Δ9-desaturase ratios 14:1/14:0 and 16:1/16:0, which were lower for TAN. Treatments did not affect total DMI, but PM tended to increase herbage DMI and reduce dry matter and crude protein digestibilities. Treatments did not affect cow eating and ruminating behavior except for the proportion of time spent eating PMR, which was higher for PM and TAN. Although no relevant effects of treatments on ruminal fermentation, purine derivatives excretion in urine, or N excretion in milk were detected, both PM and TAN decreased the total N excreted in urine by an average of 8% compared with AM. In conclusion, changing the grazing session from the morning to the afternoon and including tannins in the diet were effective in decreasing the excretion of urinary N but did not change the productive performance of dairy cows fed PMR and ryegrass herbage.
The high moisture sorghum grain silage is an important source of feed for livestock in Uruguay and some regions of the world. That is why this study aimed to evaluate the effect of ensilage time, ...moisture content, and variety on the in vitro fermentation ruminal parameters of moist sorghum grain stored in experimental silos. This study was conducted to analyze gas production in vitro of two sorghum grains varieties, with high and low-tannin content, ensiled with15–25%, 26–32%, and 33–42% moisture content 30, 90, and 180 d of ensilage in experimental silos. Total gas production was higher in low-tannin grains than in those with high-tannin, regardless of the ensilage time or the moisture content. Differences in the gas production rate were also observed in the interactions between tannin and moisture content, ensilage time, and moisture content as between tannin content and moisture contents for the lag time. Moreover, medium moisture content promoted the fermentability in high-tannin grains and high moisture in low-tannin grains. The fermentability of both high and low-tannin grains was enhanced with increasing ensilage time.
The supplementation of fresh alfalfa into the diet of growing lambs fed with decreasing levels of a total mixed ration (TMR) was studied for its effect on
in vitro
ruminal fermentation activity. ...Twenty-four catheterized lambs 25.2 ± 3.67 kg body weight (BW) were assigned to one of the following treatments: “TMR100”—TMR
ad libitum
; “TMR75’” and “TMR50”—TMR at 0.75 and 0.50 of potential intake, respectively, supplemented with alfalfa; and ‘TMR0’—only alfalfa
ad libitum
.
In vitro
gas production kinetics and true digestibility (IVTD) were evaluated using the rumen liquid as inocula. Ruminal pH values and NH
3
-N and volatile fatty acid concentrations were studied at the same time as inocula extraction. As the amount of alfalfa in the diet increased—by decreasing the level of TMR—
in vitro
gas production, ruminal pH values, NH
3
-N concentrations, and acetic acid proportions linearly increased (
p
= 0.005, 0.008, 0.004, and 0.018, respectively). IVTD tended to linearly rise (
p
= 0.083) and the fermentation rate (
p
= 0.004) and propionic acid proportion (
p
< 0.001) linearly decreased. We conclude that the increase in the level of fresh alfalfa resulting from the decrease in TMR levels in lambs’ diet positively impacted rumen fermentation activity and
in vitro
digestibility through the promotion of a suitable environment for ruminal microbiota.
This study identified the relationship between energy balance and some blood metabolites in primiparous dairy cows with different calving conception interval. Twenty primiparous Holstein-Friesian ...dairy cows were grouped according to the interval (days) from calving to conception into early-conception (early-c; <100 days), mid-conception group (mid-c; 100 - 150 days) or late-conception (late-c; >150 days) group; and evaluated on day -7 prior to parturition, and days 28, 56 and 90 postpartum. All groups presented positive energy balance, serum concentrations of HDL, urea-N and progesterone with no difference on days 28 and 56 of lactation. On day 90 of lactation all the cows presented negative energy balance; however, the early-c group presented a less intense (P < 0.05) net energy balance (-1.09 versus -2.15 and -1.86 Mcal/day), lower concentrations of serum urea-N (3.28 versus 4.22 and 4.88 mg/dL) and HDL cholesterol (0.84 versus 1.59 and 1.46 mmol/L) and greater serum concentration of progesterone (8.13 versus 4.54 and 1.83 ng/mL) than cows of mid-c and late-c groups, respectively. In conclusion, different from those usually observed for multiparous dairy cows, the energy balance during the first weeks of lactation was not a determining factor affecting the calving conception interval of primiparous dairy cows in the present study. Instead, the nutritional status and the serum concentration of urea-N and progesterone at a later stage, after 56 days of lactation, suggest having a role in delaying these cows’ pregnant status.
RESUMO: O objetivo deste estudo foi avaliar a relação entre balanço energético e concentração sanguínea de alguns metabólitos relevantes durante o início da lactação em vacas leiteiras primíparas com diferentes desempenhos reprodutivos. Vinte vacas leiteiras holandesas primíparas foram agrupadas de acordo com o intervalo parto-concepção em precoce (<100 dias), intermediário (100 - 150 dias) e tardio (> 150 dias); e foram avaliados no dia -7 pré-parto, e nos dias 28, 56 e 90 dias pós-parto. Todos os grupos apresentaram balanço energético positivo, concentrações séricas de HDL, N-uréia e progesterona sem diferença nos dias 28 e 56 de lactação. Aos 90 dias de lactação todas vacas apresentaram o balanço energético negativo, porém o grupo de vacas precoce foi menos intenso (P < 0.05) (-1.09 versus -2.15 e -1.86 Mcal/dia), menor concentração sérica de N-uréia (3.28 versus 4.22 e 4.88 mg/dL) e colesterol-HDL (0.84 versus 1.59 e 1.46 mmol/L) e maior concentração sérica de progesterona (8.13 versus 4.54 e 1.83 ng/mL), que vacas dos grupos intermediário e tardio, respectivamente. Em conclusão, diferente do observado usualmente em vacas multíparas, o balanço energético durante as primeiras semanas de lactação não foi um fator determinante do intervalo parto concepção das vacas primíparas do presente estudo. De fato, a condição nutricional e as concentrações séricas de N-ureia e progesterona após 56 dias de lactação sugere ter impacto no atraso da concepção destas vacas.
The lipid profile of milk from grazing goats supplemented with vegetable oils was evaluated. Twenty-seven Saanen goats consuming pasture were grouped and supplemented with 3 concentrates: without ...added oil (control, C) and with added sunflower (SFO) or soybean oil (SBO) until 6% ether extract (diet basis). Fat content and sensory profile of milk were not modified. Vaccenic acid increased for SBO and SFO (1.5% vs. 2.6% and 2.7% respectively; p < 0.01), and cis-9, trans-11 conjugated linoleic acid from 0.6% to 0.8% for treated groups (p < 0.01). Oil supplementation resulted effective to decrease the saturated/unsaturated ratio of grazing goat's milk.
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.
Silage of high moisture sorghum grains is a highly relevant source of energy in cattle production systems in South America. There is little information related to the chemical characteristics, the ...kinetics of fermentation and the toxic fungal populations of these feedstuffs. The aim of this study was to evaluate the effect of storage time and condensed tannins content of the grain on chemical composition, in vitro fermentation parameters, and toxicogenic fungal populations of moist sorghum grain stored in silo-bags. Samples of 2 varieties of sorghum grains (high-tannin HT and low-tannin LT), were obtained during the grain harvest before silage making and after 30, 90, and 180 d of storage (n = 16). High-tannin grains had higher acid detergent fiber, tannins, gas production (P < 0.05) and lower starch and rate of gas production (P < 0.01). Interaction variety × storage time were observed for all chemical parameters (P < 0.01), except for neutral detergent fiber assayed with a heat stable amylase and expressed inclusive of residual ash (aNDF) and pH. Starch and protein content increased in both varieties, tannins decreased in HT and LT, and organic matter (OM) increased in HT and declined in LT (P < 0.05). The rate of gas production increased with the storage time for HT and LT (P < 0.01). A linear reduction in the Aspergillus number of colonies in the HT varieties was observed (P < 0.01), whereas a linear increase in Penicillium isolation was detected in the LT sorghums (P < 0.01). The storage time was beneficial in terms of decreasing the condensed tannins, increasing fractional rate of gas production and minimizing fungal contamination, particularly on HT grains.
An outbreak of hypomagnesemia is reported in Holstein dairy cattle grazing lush oat (Avena sativa) pasture in Uruguay. Nine of 270 (3.3%) cows died in May-July (autumn-winter) 2017. These nine cows ...were from 2 to 9-years-old (1st-6th lactation), with 22 to 194 days of lactation and 15.8 to 31.4L of daily milk production. Two cows with acute sialorrhea, muscle spasms, lateral recumbency, weakness, opisthotonos, and coma, were euthanized and necropsied. No significant macroscopic or histological lesions were found. One untreated clinically-affected cow and eight out of 14 clinically healthy cows of the same group under similar management and production conditions had low serum levels of Mg (lower than 0.7mmol/L). Secondarily, both clinically affected cows and six out of 14 healthy cows had low serum Ca levels. The K/(Ca+Mg) ratio of two oat forages, corn silage, and ration was 5.10, 7.73, 2.45, and 0.85, respectively. A K/(Ca+Mg) ratio lower than 2.2 represents a risk for hypomagnesemia. The difference between the contribution-requirement of minerals in the diet was established and a daily deficiency of Mg (-0.36g/day), Na (-25.2g/day) and Ca (-9.27g/day) was found, while K (184.42g/day) and P (12.81g/day) were in excess. The diet was reformulated to correct the deficiencies and the disease was controlled by the daily administration of 80g of magnesium oxide, 80g of calcium carbonate and 30g sodium chloride per cow. It is concluded that hypomagnesemia is a cause of mortality in dairy cattle in Uruguay, and that the condition can be prevented by appropriate diet formulation.
RESUMO: Descreve-se um surto de hipomagnesemia em bovinos leiteiros da raça Holandês com alimentação a base de pastagens de aveia (Avena sativa) em crescimento no Uruguai, nos meses de maio a julho (outono-inverno) de 2017. De um rebanho de 270 vacas em ordenha, nove (3,3%) morreram. As nove vacas tinham entre dois e nove anos, estavam entre a primeira e a sexta lactação e a produção diária era de 15,8 a 31,4 litros de leite. Duas vacas que apresentaram sialorreia, espasmos musculares, decúbito lateral, debilidade, opistótono e posteriormente, estado comatoso foram eutanasiadas e necropsiadas. Não foram observadas lesões macroscópicas ou histológicas significantes. Uma vaca com sinais clínicos, não tratada, e oito de 14 vacas sem sinais clínicos, do mesmo rebanho, apresentaram baixos níveis séricos de Mg (menos de 0,7mmol/L). Adicionalmente, as duas vacas com sinais clínicos e seis das 14 vacas sem sinais clínicos apresentaram baixos níveis de Ca sérico. A relação do risco tetanizante K/(Ca+Mg) de duas pastagens de aveia, silagem de milho e ração concentrada foi estimada em 5; 10; 7,73; 2,15 e 0,85, respectivamente. Uma relação K/(Ca+Mg) maior de 2,2 é um indicador do potencial tetanizante da forragem, A diferença entre o aporte e os requerimentos dos minerais foi estabelecida constatando-se deficiência diária de Mg (-0,36g/dia), Na (-25,2g/dia) e Ca (-9,27g/dia). O potássio (K) (184,42g/dia) e o fósforo (P) (12,81g/dia) estavam em excesso. A dieta foi reformulada para corrigir as deficiências e a doença foi controlada mediante a administração diária de 80g de MgO, 80g de CaCO3 e 30g de NaCl por vaca. Conclui-se que a hipomagnesemia é uma doença de importância crescente em gado leiteiro no Uruguai e que deve ser prevenida mediante a formulação correta da dieta.
To study the effect of post-weaning feeding levels on the growth of dairy heifers, 40 animals with 77.7 ± 8.1 days of age and 77.5 ± 9.2kg of body weight were grouped in 10 pens, and each pen was ...randomly assigned to one of the following treatments for 120 days: feeding level to achieve a body weight gain of 600 (TMEDIUM) or 800 (THIGH) g/day based on a total mixed ration. After this period all heifers were managed as a single group for 150 days. Nutrient intake, behavior, body weight and other morphological measures were recorded in each animal. As a result of the experimental design THIGH heifers had a higher nutrient intake than TMEDIUM heifers, which was reflected in a higher daily weight gain, withers height, heart girth and hip width. However, treatments had no effect on these traits during the residual period.
RESUMO: Para estudar o efeito dos níveis de alimentação pós-desmame sobre o crescimento de novilhas da raça Holandês, 40 animais com 77,7 ± 8,1 dias de idade e 77,5 ± 9,2kg de peso corporal foram agrupados em 10 canetas, sendo que cada caneta foi aleatoriamente designada para um dos seguintes tratamentos por 120 dias: nível de alimentação para atingir um ganho de peso corporal de 600 (TMEDIO) ou 800 (TALTO) g/dia com base em uma ração total misturada. Após este período, todas as novilhas foram tratadas como um único grupo por 150 dias. A ingestão de nutrientes, o comportamento animal, o peso corporal e outras medidas morfológicas foram registrados em cada animal. Como resultado do delineamento experimental, as novilhas TALTO tiveram maior ingestão de nutrientes do que as novilhas TMEDIO, o que refletiu em maior ganho diário de peso corporal, altura dos gomos, circunferência do coração e largura do quadril. No entanto, os tratamentos não tiveram efeito sobre estas variáveis durante o período residual.
Abstract
The objective of this study was to quantify the emissions of enteric CH4 from growing Hereford steers raised under feedlot conditions based on contrasting levels of residual feed intake ...(RFI). A repeated measurements experiment was conducted over 20 d to determine CH4 production from two groups of nine Hereford steers, with contrasting RFI values (mean ± SD): low RFI (LRFI group; −0.78 ± 0.22 kg DMI/d) vs. high RFI (HRFI group; 0.83 ± 0.34 kg DMI/d). Steers were selected from a larger contemporary population in which the RFI was evaluated. Steers were maintained under confined conditions with ad libitum access to water and feed, comprising a total mixed ration of 55% sorghum silage, 21% barley silage, 21% corn grain, and 3% protein–mineral–vitamin–premix, provided twice a day. Before the beginning of CH4 measurements, the live weight of both groups of animals was determined, which on average (±SEM) was 357.0 ± 5.11 and 334.0 ± 10.17 kg in the LRFI and HRFI groups, respectively. Methane emission (g/d) was measured on each animal with the sulfur hexafluoride (SF6) tracer technique, during two consecutive periods of 5 d. Individual daily intake and feeding behavior characteristics were measured using a GrowSafe automated feeding system (Model 6000, GrowSafe Systems Ltd, Airdrie, Alberta, Canada). Methanogens in the ruminal content were quantified using quantitative polymerase chain reaction with primers targeting the mcrA gene. Methane emission was near 27% lower in animals with LRFI when expressed in absolute terms (g/d; 26.8%; P = 0.009), by unit of dry matter intake (g CH4/kg; 27.9%, P = 0.021), or as % of gross energy intake (26.7%; P = 0.027). These differences could not be explained by differences in amount of total of methanogens (average = 9.82 log10 units; P = 0.857). However, there were some differences in animal feeding behavior that could explain these differences (e.g., LRFI animals tended to spend less time in feeders). Our results suggest that, in Hereford steers, the selection by RFI values is a promising mitigation strategy for the reduction of the emission of enteric CH4.
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