Zebu Heifers Research Articles

Carbohydrates and protein digestive traits in beef cattle grazing fertilised or mixed tropical pasture

ABSTRACT This study was performed to investigate the nitrogen (N) and carbohydrate digestive traits of grazing heifers. The experiment was carried out at the Federal University of Lavras. The treatments were a Marandu palisadegrass (Urochloa brizantha [Syn, Brachiaria brizantha] Stapf. A. Rich. cv. Marandu) monoculture fertilised with 150 kg N/[ha ∙ year] (FP) or Marandu palisadegrass mixed pasture with forage peanut (MP). The pastures were grazed by six rumen-cannulated zebu heifers. A double cross-over design was used in four periods. Nutritive value, intake and apparent digestibility of forage, ruminal traits and kinetics and N balance were evaluated. Apparent total-tract digestibility of dry matter (DM) and neutral detergent fibre (NDF) were greater for FP than for MP. There was no effect in apparent total-tract digestibility of N. The estimated intestinal digestibility of nutrients was greater on MP than FP. Even though N intake and faecal N output were greater on MP than FP, there was no effect in urine N output. The N balance tended to be greater on MP than FP. The forage peanut, which contains condensed tannins, decreased ruminal fibre degradation, apparent digestibility and ruminal protein degradation, increased N flow from the rumen. Inclusion of forage peanut in the mixed pasture decreased the ruminal fibre degradability but increased N retention by the animals.

Association between chitosan and unsaturated fatty acids supplementation on ruminal fermentation, digestive metabolism, and ruminal kinetics in beef heifers

This study evaluated the effects of supplementation of chitosan and unsaturated fatty acid (UFAs) sources on intake, digestibility, ruminal and nitrogen metabolism, blood metabolites, and feeding behavior of beef heifers. Five crossbred Simental x Zebu heifers (335 ± 53.2 kg of initial BW), ruminally cannulated, were randomly assigned according to a 5 × 5 Latin square design containing the following treatments: 1) CON, the control diet without supplementation; 2) SO, control diet supplemented with 25.3 g/kg of soybean oil; 3) WRS, control diet supplemented with 160 g/kg of whole raw soybean (WRS); 4) SOCHI, SO diet plus 14 g/kg of CHI; 5) WRSCHI, WRS diet plus 14 g/kg of CHI. No interaction effects between CHI and WRS were observed on nutrient intakes and digestibilities. Heifers fed SO, or WRS diets with or without CHI had lower enteric methane (CH4) emissions (P < 0.01) than those fed CON. Moreover, animals fed SO and WRS had higher CH4 emissions than those fed SOCHI and WRSCHI. No interaction between CHI and WRS was observed on nitrogen balance. However, heifers fed SO or WRS diets with or without CHI had lower nitrogen (N) intake (P = 0.001) and fecal N (P = 0.015) than those fed CON. Besides, animals fed SO and WRS diets showed lower retained N (P = 0.010) and efficiency (P = 0.005) than those fed SOCHI and WRSCHI. Heifers fed SO, or WRS diets with or without CHI showed lower rumination efficiencies of dry matter (DM; P < 0.01) and neutral detergent fiber (NDF; P = 0.013) than those fed CON. Heifers fed SO or WRS with or without CHI, showed lower reticular flows of DM (P = 0.049), NDF (P = 0.002), and potentially digestible NDF (P = 0.002) than those fed CON. In addition, animals fed SO or WRS diets with or without CHI showed a lower rumen digestion rate of DM, turnover rates of DM and NDF, and passage rates of DM and pdNDF than those fed CON. The supply of CHI to beef heifers fed diets with SO and WRS alters ruminal fermentation, methane production, nitrogen balance, feeding behavior, and ruminal dynamics. Nevertheless, the results strengthen the evidence that the provision of CHI in beef cattle diets can positively influence the effect of fatty acid sources. Besides, fatty acids sources provided alone have a negative influence on most metabolism parameters in beef heifers.

Tropical grass silages with spineless cactus in diets of Holstein × Zebu heifers in the semiarid region of Brazil.

One of the factors that limit ruminant production in the semiarid region is the lack of roughage in the dry season. The management of forage plants adapted to edaphoclimatic conditions is a strategy to improve animal production. This study was conducted to examine the effects of biomass sorghum silage (BSS; Sorghum bicolor (L.) Moench) and BRS capiaçu grass silage (CGS; Pennisetum purpureum Schum) with or without spineless cactus (Opuntia spp.) in crossbred Holstein × Zebu heifers' diets on the intake, apparent digestibility of the nutrients and animal performance (e.g., final weight, daily weight gain) (experiment 1). Also, to evaluate the ruminal kinetics of dry matter (DM) and neutral detergent fiber (NDF) of roughages used in diets using two animals cannulated in the rumen (experiment 2). In experiment 1, ten heifers with an initial body weight of 200 ± 2.74kg (mean ± standard deviation) and a mean age of 10months were used. The animals were distributed in an experimental design in two simultaneous 5 × 5 Latin squares. Five experimental diets were used: diet 1, Volumax sorghum silage (VSS); diet 2, biomass sorghum silage (BSS); diet 3, BRS capiaçu silage (CGS); diet 4, biomass sorghum silage (60%) with spineless cactus (40%) (BSS + SC); and diet 5, BRS capiaçu grass silage (60%) with spineless cactus (40%) (CGS + SC). The diets were formulated with sorghum silage or BRS capiaçu grass silage with or without spineless cactus (roughage) and a maize- and soybean-based concentrate (75:25 roughage-to-concentrate ratio) on DM basis. The experiment lasted 105days, divided into five periods of 21days (17days for the adaptation of the animals to the diets and management and 4 for data collection and samples). The diets containing CGS and CGS + SC resulted in lower dry matter intake (DMI; 5.61kgday-1; P < 0.01), which was 19.4% lower than the diets with VSS, BSS, and BSS + SC (7.00kgday-1). The BSS + SC and CGS + SC diets showed higher crude protein digestibility (P < 0.01) at 21.9% than the other treatments (Volumax, BSS, CGS). The different diets did not change the final weight or the daily weight gain of the heifers. The BRS 716 biomass sorghum silage and BRS capiaçu grass combined with spineless cactus increased (P < 0.05) the intake of nonfibrous carbohydrates and did not interfere (P > 0.05) with the final weight or average daily gain of the crossbred Holstein × Zebu heifers. The standardized potentially degradable fraction (Bp) of the NDF was 13.91% higher (P < 0.01) for BSS and BSS + SC (61.6%) compared to the others (53.0%). A diet based on BSS + SC is recommended for feeding crossbred heifers in the growing phase.

Nutritional parameters and performance of crossbred heifers fed with millet and BRS 716 biomass sorghum silages

ABSTRACT This study addressed the different proportions of millet and sorghum silage biomass BRS 716 (BRS-716 silage) in the diet of crossbred heifers ¾ Holstein x ¼ Zebu on their nutrient intake, and digestibility, microbial protein synthesis, nitrogen balance, ingestive behaviour, and growth performance. Five experimental diets with 0, 25/75, 50/50, 75/25, and 100% of BRS-716 silage in compared to millet silage were evaluated. The roughage: concentrate ratio in the total dry matter (DM) of the diets was 75:25. The diets were evaluated in ten heifers with an initial body weight of 264.95 ± 19.4 kg (± SEM), following the experimental design in two 5 × 5 Latin squares, simultaneously. The total experimental period lasted 105 d, divided into five periods of 21 days, including a 17-d initial adaptation, and four for data collection, and samples. The increase of BRS-716 silage in the diet of crossbred dairy heifers did not change the dry matter intake (DMI), and indigestible neutral detergent fiber (iNDFI). For the purine derivatives, and microbial synthesis, there was no significant effect (P > 0.05). The average daily gain was 0.795 kg/d. The millet silage, and BRS-716 silage in the diet of crossbred Holstein × Zebu heifers used exclusively or combined in different proportions.

Association of virginiamycin and multiple supplement for cattle fed a high-quality tropical forage

The aim of this study was to evaluate the effect of adding virginiamycin to either mineral mixture or multiple supplement on intake, digestion, ruminal fermentation profile, rumen microbial production, blood metabolites, and liver metabolism of zebu heifers fed a high-quality tropical forage. Eight Brahman heifers were assigned to a replicated 4 × 4 Latin Square design. The treatments were: mineral mixture, mineral mixture with virginiamycin, multiple supplement, and multiple supplement with virginiamycin. The basal diet consisted of a high-quality Tifton 85 hay (Cynodom sp.) chopped at 10-cm particle size and fed twice daily. The mineral mixture was provided daily at 120 g/animal. The multiple supplement was formulated to provide 300 g of crude protein (CP)/kg as fed, contained mineral mixture, corn grain, and urea: ammonium sulfate, and was daily provided at 200 g/animal. The mineral mixture and multiple supplement provided the same daily amount of minerals. The amount of supplemental virginiamycin was based on a maximum theoretical response on animal performance (50 mg/100 kg body weight) and daily mixed to the supplements types. The treatments were compared according to a 2 × 2 factorial arrangement (mineral mixture and multiple supplement, with or without virginiamycin). The virginiamycin supplementation did not alter either voluntary intake or digestibility (P≥0.44). Using the multiple supplement decreased forage (P&amp;lt;0.05) and digested organic matter (DOM, P&amp;lt;0.10) intake, but increased dietary CP : DOM ratio (P&amp;lt;0.01). The multiple supplement increased the ruminal ammonia concentration (P&amp;lt;0.04) and the acetate-to-propionate ratio (P&amp;lt;0.06). Virginiamycin increased urinary nitrogen (N) when provided along with multiple supplement (P&amp;lt;0.05). Fecal N was decreased by multiple supplement (P&amp;lt;0.06). Despite these effects, no effect was verified on either body N accretion (P≥0.48) or microbial N production in the rumen (P≥0.27). Virginiamycin decreased the blood IGF-1 (P&amp;lt;0.07). The hepatic gene expression for propionyl-CoA carboxylase was increased by virginiamycin (P&amp;lt;0.01). Virginiamycin increased the hepatic gene expression of both citrate synthase and pyrivate carboxylase when mineral mixture was provided (P&amp;lt;0.01), but decreased it when animals were fed multiple supplement (P&amp;lt;0.04). Using a low-intake multiple supplement with a high CP content for cattle fed high-quality forage causes a substitutive effect on forage intake, but keeps nitrogen accretion unchanged. That pattern indicates an improvement in feed efficiency. On the other hand, virginiamycin supplementation seems to cause some post-prandial influences, which may vary according to the type of supplement. Those influences apparently improve animal efficiency.

Increasing shade area in feedlot heifers during heat stress: physiological and performance parameters.

Heat stress is a great challenge for feedlot operations established in arid zones. The aim of this study was to evaluate if increasing shade area in the pen improved physiological and productive variables in feedlot heifers under hot climate. A total of 510 European and Zebu heifers were randomly assigned to six pens which were divided in two treatments: (1) three pens with 100 heifers each with a shade area of 2.7 m2/head (control group [C]); and (2) three pens with 70 heifers each with a shade area of 3.7 m2/head (treated group [T]). Physiological variables respiratory frequency (RF) and body surface temperature (BST) of several anatomic regions were taken from 30 heifers per treatment (i.e., 10 heifers/pen). Feed intake on pen basis was recorded weekly and heifers were individually weighted on days 1, 26, and 66 of the study to calculate performance variables. Relative humidity (RH) and ambient temperature (AT) were recorded and used to estimate the temperature-humidity index (THI). Data was analyzed with analysis of variance. The average THI during the study was 81.7 units, which was categorized as dangerous heat stress. In both shaded areas, European heifers showed higher (P < 0.05) RF than Zebu heifers. In the afternoon, the temperature of head, neck, loin, paddle, and belly was higher (P < 0.05) in C compared with T. Heifers under T showed better (P < 0.05) daily weight gain (DWG), total weight gain (TWG), feed conversion (FC), and feed efficiency (FE) than heifers in C, with no effect on dry matter intake (DMI). Results indicate that during hot summer months, Zebu showed more tolerance to heat stress than European heifers; however, heifers under a shade area of 3.7 m2/head had better productive performance than those under a shade area of 2.7 m2/head during the finishing phase of the feedlot. Increasing the shade area in the finishing phase of beef cattle on feedlot improved some physiological and productive responses during heat stress.

Effect of replacement of forage sorghum silage with biomass sorghum silage in diets for dairy heifers

This trial aimed to analyze the replacement of forage sorghum silage (FS silage) with biomass sorghum silage (BRS 716 silage) in diets for heifers ¾ Holstein x ¼ Zebu on their nutrient intake and digestibility, nitrogen balance, microbial production, feeding behavior, and animal performance. Eight heifers with average age 18±4 months (mo) and average body weight (BW) 271 ± 57 kg were used. The experimental design was double-Latin square, 4×4, being four diets, four experimental periods and four animals. Four experimental diets with 0, 33, 67 and 100% substitution of forage sorghum silage with biomass sorghum silage were used. The roughage:concentrate ratio in the total dry matter (DM) of the diets was 75:25. The fraction “b” of DM was higher in the BRS 716 silage. There was no difference (p&gt; 0.05) for dry matter intake (DMI; p = 0.45) and total digestible nutrients intake (p = 0.76). The dry matter digestibility (DMD), crude protein, ether extract and neutral detergent fiber increased linearly with the inclusion of BRS 716 silage. The feeding times, ruminating and idle have not been changed (p &gt; 0.05). The replacement of FS silage with BRS 716 silage did not modify the average daily weight gain (ADG; p &gt; 0.05; mean 1.30 ± 0.025 kg). Biomass sorghum silage can replace up to 100% forage sorghum silage in the diets of ¾ Holstein x ¼ Zebu heifers.

Effect of heat stress on ingestive, digestive, ruminal and physiological parameters of Nellore cattle feeding low- or high-energy diets

This study aimed to verify the effects of heat stress and dietary energy level on dry matter intake (DMI), water intake, total and partial ruminal and intestinal digestibilities, ruminal characteristics, physiological and digestive behavioral parameters in beef cattle. Six ruminally cannulated Nellore heifers (280 ± 12 kg) were used in a 6 × 6 Latin square experiment with six treatments and six periods of 21 days. The treatments consisted of a 2 × 2 + 2 factorial arrangement, with two temperatures during the day (thermoneutrality, TN: 24°C; and heat stress, HS: 34°C), two dietary energy levels (low- or high-energy concentration) and two additional treatments of animals maintained in TN conditions but pair-fed with the heifers in HS (PFTN). The HS decreased DM intake by about 16% and increase water intake by 25.5% respectively (P ≤ 0.01). Heifers maintained in TN and fed high-energy diet showed 17.3 and 14.3% greater ruminal dry matter (DM) and organic matter (OM) digestibilities compared to their HS counterparts. The DM intake rate (ki, h−1) and digestion rates (kd, h−1) were affected by environment and dietary energy level (P ≤ 0.01), which heifers in HS having lower ki and kd. Heifers in HS presented lower pH and greater ruminal temperature values (P ≤ 0.01). When PFTN treatments were compared vs. HS, there was a significant effect of temperature on acetic acid. Heifers that underwent HS showed 14 % less acetic acid. The ocular temperature, body temperature, heart rate, and respiratory rate were greater in HS heifers (P ≤ 0.01) than in TN. Heifers with low energy level diets showed 33% greater values of rumination time (P = 0.05) when compared to high energy levels independent of the temperatures. We concluded that adaptive response to heat seems important factors responsible for the alteration of DMI, water, and other nutritional fractions like OM, CP, and energy intake. On the other hand, increments in intestinal digestibility in zebu heifers suggest an adaptive response of the digestive tract to heat stress conditions.

The Economic Loss of Dairy Cattle Poor Reproductive Performance inCentral Highlands of Ethiopia

The purpose of the study was to quantify the economic loss due to delayed conception in dairy cows and heifers in central highlands of Ethiopia using data collected from 298 randomly selected dairy farmers of Oromia and Amhara national regional states. The study covered two zones of Oromia (Finfine special zone and North Shoa) and one zone of Amhara (North Shoa). A three-stage sampling technique was employed to select the sample for the study which involved purposive and random sampling techniques. The data collection was done using a structured questionnaire. Both descriptive and inferential statistics were used to analyze the data. The total loss due to poor reproductive performance per year per cow/heifer was the aggregate of milk loss, extra feed cost, extra medical cost, breeding cost, calf loss, and extra labor. The result of the study revealed that the mean annual cost of the poor reproductive performance of the crossbreed cow was ETB 32,068.53 (US $1,167.40) with the mean per day cost of ETB 157.43 (US $5.73). On the other hand, the mean annual cost of poor reproductive performance of local zebu cows was ETB 15,696.34 (US $571. 39) with the mean per cow per day cost of ETB 54.90 (US $2.00). Based on the results, a high proportion of poor reproductive performance cost of crossbreed cows goes to milk loss (53%) and extra feed cost (39%), and the highest proportion goes to cost of milk loss (53%) and cost of extra feed (33%) for local zebu cows. Concurrently, the cost of poor reproductive performance (delayed conception) for crossbreed heifers was ETB 69,333.59 (US $2,523.97) with a mean per heifer per day cost of ETB 151.75 (US $5.52), and the mean cost of poor reproductive performance of local zebu heifers along the study zones was ETB 27,010.75 (US $ 983.28) with a mean per day per heifer cost of ETB 52.56 (US $1.91). More than 55% of the cost goes to milk loss for both crossbreed and local zebu heifers. The study has also estimated the cost of delayed conception in central Ethiopia. The estimated result showed that poor reproductive performance of crossbred cows annually costs ETB 2,053,022,879.41 (US $74,736,908.61). On other hand, poor reproductive performance of local zebu cattle costs ETB 14,802,637,790.05 (US $538,865,591.19). Thus, it is suggested to work on AI efficiency, timely culling, and using crossbreed dairy cattle to reduce the economic losses caused by delayed conception.

Effects of different banana crop wastes on nutrient intake and digestibility, microbial protein synthesis, feeding behavior, and animal performance of ¾ Holstein × Zebu heifers in a semiarid rangeland.

The objective of this study was to evaluate the use of banana crop wastes in diets of ¾ Holstein × ¼ Zebu heifers on the intake and digestibility of nutrients, microbial protein synthesis, feeding behavior, and animal performance. Eight ¾ Holstein × ¼ Zebu heifers were utilized with an average age of 18 ± 1.0 months and an average body weight (BW) of 298 ± 3.06 kg. The experiment was distributed in two simultaneous 4 × 4 Latin squares. The treatments were as follows: Diet 1 (SS)-sorghum silage as exclusive dietary roughage; diet 2 (SSL)-sorghum silage (50%) associated with 50% leaf hay of banana trees (on a DM basis); diet 3 (SSBP)-sorghum silage (50%) associated with 50% banana peel hay; and diet 4 (SSPS)-sorghum silage (50%) associated with 50% pseudostem hay of banana trees. The roughage:concentrate ratio was 75:25. The greatest dry matter intake (DMI; p < 0.01) was found in heifers that received the SS and SSBP diet, mean of 10.19 kg/day. The SS diet showed greatest dry matter digestibility (DMD; p < 0.01) and crude protein digestibility (CPD; p < 0.01). The concentration of total purines (p < 0.01) and absorbed purines (p < 0.01), microbial protein synthesis (p < 0.01), and microbial efficiency (p < 0.01) was higher in the SSBP diet in comparison with SS and SSL diets. The longest eating time was observed in animals that received the SSL diet, being 17.79% higher (p = 0.01) than the SSBP diet. The final BW (p = 0.39) and BW gain (p = 0.39) were similar, with averages of 319.84 kg and 1.08 kg/day, respectively. Biometric measurements were not altered as a function of bedtime (p > 0.05). Banana wastes can be used to feed ¾ Holstein × ¼ Zebu heifers in partial replacement for sorghum silage as they do not alter the animals' weight gain and body development.

Estimating purine derivatives and nitrogen compound excretion using total urine collection or spot urine samples in grazing heifers.

The study aimed to evaluate the excretion of purine derivatives (PDs) and nitrogen compounds (NCs) and their ratios with creatinine in supplemented Zebu heifers kept on pastures by comparing total urine collection and spot sampling. Five Nelore heifers (400±15kg) were used in a 5×5 Latin square design. The treatments were the amount of concentrate (220g of crude protein/kg dry matter) offered (0, 3, 6, 9 and 12g/kg BW). In each period, the total urine collection was performed continuously for 3days (subsampled at intervals of 4h, 00:00-04:00h, 04:00-08:00h, 08:00-12:00h, 12:00-16:00h, 16:00-20:00h and 20:00-24:00h). The spot urine samplings were performed (in each period) for 24h (0, 4, 8, 12, 16 and 20h). Creatinine, total urinary nitrogen (UN), urea nitrogen (UreaN), allantoin and uric acid were analysed. Creatinine excretion was 23.01±0.19mg/kg BW and was not affected by collection day, treatment or their interactions (p>0.05). Treatments affected (p<0.05) PD excretions, however did not affect the ratio PD:creatinine (p>0.05). Treatments and collection time affected (p<0.05) NC excretion, whereas the UN:creatinine and UreaN:creatinine ratios were not affected (p>0.05). Creatinine excretion and the PD:creatinine ratios in the urine samples estimated by the total or spot sampling were not different (p>0.05). However, sampling method affected (p<0.05) the UN:creatinine and UreaN:creatinine (p<0.05) ratios. Creatinine can adequately estimate urinary excretion in grazing heifers, and a single spot urine sample at any time of the day can be used to estimate PD excretion in grazing heifers. But two spot urine samples are needed for proper NC excretion estimations in grazing heifers' urine.

Beef Production on Rotationally Grazed F1 Pennisetum Hybrid and Elephant Grass (Pennisetum Purpureum Schum.) Pastures

COMPARATIVE studies of elephant and the F1 hybrids between the ‘maiwa’ Cultivar of millet (Pennisetum americanum) elephant grass (P. purpureum) indicated a superiority in quality of the hybrids. To ascertain this potential superiority animal performance was measured by exciting beef production on F1 Pennisetum hybrid and elephant grass pastures consisting of random mixture of genotype which were grazed from July 28 to December 6. 1972 (132 days) by 18 to 24 months old White Falani (Bunaji) Zebu heifers. Each pasture was divided into Six 0.07- ha paddocks which were grazed in rotation by two heifers for 5 to 7 days with intervening rest periods of 30 to 35 days. Total liveweight gains per hectare, of animals grazing F1 Pennisetum hybrid and elephant grass pastures were 246.71 and 171.77kg respectively. Mean daily liveweight gain per 100 Kg body weight of animals on the F1 Pennisetum hybrid nature was 0.18 kg which was significantly higher than the 0.13 kg of animals grazing elephant grass. Dry matter (DM) utilisation and average daily intake of the F1 hybrids and elephant grass were respectively, 46 and 35% and 2.2 an 2.0% of body weight while 11.71 kg and 15.85 kg of F1 Pennisetum hybrids and elephant grass, respectively, were consumed per kg of liveweight gain. The superior performance of animals grazing F1 hybrid Pennisetum, was attributed to the higher intake and more efficient conversion of the hybrids. Stand mortality of F1 Pennisetum hybrids and elephant grass at the end of the study were 25 and 15%, respectively. Greater animal output can be expected from F1 Pennisetum hybrids selected for improved DM production quality and plant persistence.

Beef Production on Rotationally Grazed F1 Pennisetum Hybrid and Elephant Grass (Pennisetum Purpureum Schum.) Pastures

Comparative studies of elephant grass and the F1 hybrids between the 'maiwa' cultivar of millet ( Pennisetum americanum ) and elephant grass ( P. purpureum ) indicated a superiority in quality of the hybrids. To ascertain this potential superiority animal performance was measured by estimating beef production on F1 Pennisetum hybrid and elephant grass pastures consisting of random mixtures of genotypes which were grazed from July 28 to December 6, 1972 (132 days) by 18 to 24 months old White Fulani (Bunaji) Zebu heifers. Each pasture was divided into six 0.07-ha paddocks which were grazed in intervening rest periods of 30 to 35 days. Total liveweight gains per hectare, of animals grazing F1 Pennisetum hybrid and elephant grass pastures were 246.71 and 171.77 kg respetively. Mean daily liveweight gain per 100 kg body weight of animals on the F1 Pennisetum hybrid pasture was 0.18 kg of animals grazing elephant grass. Dry matter (DM) utilisation and average daily intake of the F1 hybrids and elephant grass were respectively, 46 and 35% and 2.2 and 2.0% of body weight while 11.71 kg and 15.85 kg of F1 Pennisetum hybrids and elephant grass, respectively, were consumed per kg of liveweight gain. The superior performance of animals grazing F1 Pennisetum hybrids was attributed to the higher intake and more efficient conversion of the hybrids. Stand mortality of F1 Pennisetum hybrids and elephant grass at the end of the study were 25 and 15%, respectively. greater animal output can be expected from F1 Pennisetum hybrids selected for improved DM production quality and plant persistence.

Does environmental enrichment consisting of brushing prepartum zebu heifers improve first-lactation behavior?

To date, Qualitative Behavior Assessment (QBA) has not been used to measure the welfare of pre-partum Zebu heifers treated with practices of positive handling. The study objective was to investigate the effect of brushing as positive handling on animal behavior in the prepartum period, aside from establishing a qualitative behavior index to assess the animals’ well-being pre- and postpartum periods. Thirty-five Zebu, 21 Gyr and 14 Gyr/Holstein heifers were evaluated. Filming was performed during the prepartum period, and on postpartum day (PPD) 1, 5 and 15. The filmed material was evaluated based on the method of Qualitative Behavior Assessment (QBA). A total of 1942 evaluation sheets with 10 fixed descriptive terms were analyzed. The means of Qualitative Behavior Index (QBI) were compared by the Tukey-Kramer test at 5% probability. On PPD1, training improved the QBI of Gyr and Gyr/Holstein heifers by 93 % and 43 %, respectively. The cumulative sum of the first two components explained 73.32 % of the variability in the datasets. High correlations were observed between the undesirable adjective pairs “nervous - aggressive” and “scared - irritable” (0.88); “confused-fearful” and “scared - irritable” (0.87) and between the desirable adjectives “calm - even-tempered” and” sociable - friendly” (0.78). The use of QBA to measure the welfare of pre- and postpartum Zebu heifers is applicable and efficient. The implementation of a training of prepartum Zebu heifers with environmental enrichment, tactile stimulation by brushing and human presence improved the adaptation of Zebu heifers to the postpartum milking system. We suggest brushing of Gyr heifers in the pre- as well as postpartum phases to improve the well-being of the animals.

English

The study was undertaken to explore the nutritive potential of cassava leaves and Azolla as supplementary source of crude protein to cattle fed on either mixed range grass hay or Bracharia Mulato II. Two experiments were carried out, the first was the determination of the biomass yield of Azolla, its relative growth rate and doubling time while the second was a feeding trial to determine the performance of small East African Shorthorned Zebu heifers of similar age and weight. The heifers (four each) were randomly assigned to six treatments in the feeding trial that ran for 16 weeks. The doubling time for Azolla was 5 days while the relative growth rate was 0.15 g/g/day. The chemical analysis indicated that Azolla is rich in crude protein (18.8%) and minerals (3.29% calcium, 2.66% potassium and 0.15% phosphorus and other minerals in trace levels). All the supplemented groups showed more weekly weight gains ranging from 0.75 to 1.11 kg per day more than the control. Overall, the treatment with Azolla or cassava showed slightly higher but insignificant increases in weight gains. Azolla and cassava leaves can therefore be considered as potential feed for livestock. Key words: Arid and range lands, cattle, doubling time, relative growth rate.

Efeito de dispositivos vaginais impregnados com alta ou baixa concentração de progesterona na taxa de prenhez de novilhas submetidas à inseminação artificial em tempo fixo

This study aimed to evaluate the use of low- or high-dose intravaginal progesterone (P4)-releasing devices on pregnancy rates of Zebu heifers submitted to fixed-timed artificial insemination (TAI). Pubertal Bos indicus Nellore heifers were injected at day 0 with 2 mg estradiol benzoate (EB) and assigned randomly to three groups. Anintravaginal device containing 1.9 or 0.75 g P4 was inserted in animals of groups 1 (n=80) and 2 (n=79), while group 3 (n=76) received no device. The intravaginal devices were removed on day 8 and one luteolytic dose (125 μg) of d-cloprostenol was administered. Half of the animals in each group additionally received 300 IU of eCG. Twenty-fourhours later, the heifers received a second injection of 1 mg EB and TAI was performed 54 hours after the injection of cloprostenol. Pregnancy was diagnosed 40 days after TAI by transrectal ultrasonography. Data were analyzed by logistic regression. Pregnancy rates were 27.5%, 30.4% and 28.9% in groups 1, 2 and 3, respectively (P>0.05). This resultwas not influenced by body score, farm, eCG, or presence of CL at the beginning of the treatments. In conclusion, the use of intravaginal devices containing either a high (1.9 g) or low (0.75 g) dose of P4 resulted in similar pregnancy rates after TAI in pubertal Nellore heifers.

EVOLUÇÃO APÓS QUATRO ANOS DE APLICAÇÃO DA CAPACIDADE ANDROLÓGICA POR PONTOS (CAP) EM TOUROS NELORE E ESTUDO DA RELAÇÃO COM A PRENHEZ EM ESTAÇÃO DE ACASALAMENTO

Resumo Estudou-se a evolução da capacidade andrológica por pontos (CAP) de 1092 touros Nelore, mantidos a pasto, durante quatro anos, e sua relação com a porcentagem de prenhez após uma estação reprodutiva. A cada ano, realizaram-se avaliações clínico-andrológicas em que mediu-se o perímetro escrotal (PE) e se coleou sêmen por eletroejaculação, para avaliação dos aspectos físicos e morfológicos dos ejaculados. A partir dos pontos obtidos pelo PE (PEP), motilidade progressiva (MOT) e morfologia espermática (MORF), computaram-se os CAP. Na estação de monta foram utilizadas 4319 fêmeas e 256 touros Nelore, em regime de pasto, para avaliação da fertilidade do rebanho. Após a escolha de 157 touros dentro das faixas A-C do CAP, foram estabelecidos, aleatoriamente, 15 grupos de touros para diferentes categorias e quantidade de fêmeas. Nos quatro anos de estudo houve aumento significativo do CAP, de 59,5 a 79,0. A PEP, MOT e MORF aumentaram no mesmo período de 17,5, 12,7 e 29,3 para 30,1, 14,8 e 34,4, respectivamente (P&lt;0,05). Foram observadas correlações entre o CAP com os seus componentes, o ano e as características reprodutivas estudadas. Houve aumento significativo de touros enquadrados nas categorias A e B do CAP de 9,0% e 46,9% vs. 43,5% e 44,8%, respectivamente. O CAP e a porcentagem de prenhez das fêmeas foram de 82,0 ± 13,2 pontos e 83,1 ± 8,4 %, respectivamente. Houve correlação (P&lt;0,001) entre o CAP e a taxa de prenhez (r=0,25). A utilização de grupos de touros das faixas A e B do CAP favoreceu o aumento da percentagem de prenhez no rebanho. A relação touro:fêmea observada sub-utiliza o potencial reprodutivo dos touros. A técnica empregada foi importante para avaliar a fertilidade potencial e modificar as características reprodutivas da população de touros estudada.

Effect of different forage types and concentrate levels on energy conversion, enteric methane production, and animal performance of Holstein × Zebu heifers

The aim of this study was to evaluate the effect of diets containing corn silage (CS) or sugarcane (SC) with 300 or 500 g/kg of concentrate (on a DM basis) on energy conversion, enteric methane (CH4) production, and the animal performance of Holstein × Zebu heifers. An experiment was conducted while using comparative slaughter. Twenty Holstein × Zebu heifers with an average age of 12 ± 1.0 months and an average bodyweight of 218 ± 36.5 kg were used. Four heifers were assigned to a baseline group, whereas the remaining 16 heifers were distributed in a completely randomised design using a 2 × 2 factorial scheme (n = 4), with two types of roughage (CS or SC) and two levels of concentrate (300 or 500 g/kg) on a DM basis of the diet over the course of 112 days. For the evaluation of the apparent total-tract digestibility of diets and energy losses, a digestibility assay was performed by using the total collection of faeces and urine over three consecutive days. The enteric CH4 production was quantified by continuous analysis of regular samples of air excreted by the animals throughout the day. The greatest (P &lt; 0.05) average daily gain was observed for heifers that were fed CS-based diets or with 500 g/kg of concentrate. Greater (P &lt; 0.05) daily CH4 emissions were observed for heifers that were fed 500 g/kg of concentrate; CH4 production as a function of DM intake was greater (P &lt; 0.05) for heifers that were fed SC-based diets. The efficiency of the conversion from digestible energy (DE) to metabolisable energy (ME) was not influenced (P &gt; 0.05) by variables that were analysed in this study. However, the mean value that was observed in the present study was above those values proposed by the main evaluation systems of feedstuffs and nutrient requirements of ruminants. Therefore, we concluded that CS-based diets allow for better animal performance of Holstein × Zebu heifers in relation to SC-based diets. Also, the increased concentrate improves the performance of growing heifers. A greater inclusion of concentrate in SC-based diets can allow for a reduction of CH4 emissions per consumed unit and per gain unit. The mean suggested value for the ME : DE ratio based on this study is 0.86. However, more studies are necessary to validate this result.

Feedlot performance, carcass characteristics and meat quality of Zebu heifers supplemented with two β-adrenergic agonists

The aim was to evaluate effects of administration of two β-adrenergic agonists (β-AA) on growth performance, carcass characteristics and meat-quality traits of Zebu heifers finished in a feedlot. Fifty-four Zebu heifers weighing 397 ± 29.1 kg were used in a randomised complete block design with three treatments and six blocks (i.e. 18 pens with 3 heifers per pen). Treatments were as follows: (1) control (C; no supplement); (2) zilpaterol hydrochloride (ZH; 60 mg per heifer per day); and (3) ractopamine hydrochloride (RH; 300 mg per heifer per day). The β-AA were added to the diets during the final 33 days of the finishing period, after which the heifers were immediately slaughtered. Relative to C, average daily gain and gain : feed ratio were improved (P &lt; 0.05) in heifers supplemented with ZH, but not in those supplemented with RH. Feed intake in C heifers was lower (P &lt; 0.05) than in ZH heifers, but similar (P &gt; 0.05) to RH heifers. The hot carcass weight showed a trend to be heavier (P = 0.096) in ZH than in C heifers. However, Longissimus dorsi (LM) area was increased (P &lt; 0.05) by ZH (73.94 cm2), but RH (70.45 cm2) and C (66.3 cm2) groups had a similar (P &gt; 0.05) LM area. The meat from the ZH- and RH-supplemented heifers had higher Warner–Bratzler shear-force values (P &lt; 0.01) than that from C heifers (ZH = 5.11; RH = 5.50; C = 4.89 kg/cm2), and the meat from RH-supplemented heifers was classified as ‘tough’. Variables associated with meat colour indicated that ZH led to a lower b* average, which was related to a lighter LM area than in C. In general, feedlot performance was enhanced only by the β-AA ZH, with meat tenderness from RH heifers classified as ‘tough’. Meat colour was not altered by β-AA supplementation. These data suggested that while ZH supplementation to Bos indicus heifers offered advantages in feedlot performance and some carcass traits, RH supplementation did not positively affect these biological responses.

Live-weight gains of Holstein × Zebu heifers grazing a Cratylia argentea/Toledo-grass (Brachiaria brizantha) association in the Mexican humid tropics

The legume Cratylia argentea associated to Brachiaria brizantha—Toledo-grass (Bb + Ca) and Toledo-grass alone (Bb) were evaluated under grazing conditions by Holstein × Zebu heifers. Three evaluation periods during three consecutive years, were performed. We measured, daily live-weight gains of heifers (DWG, g/day); biomass dry matter (BDM, kg/ha) at beginning and end of each grazing period. On plant samples, were measured percentages of crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, in situ DM degradability (ISDMD), and voluntary biomass DM intake (VBI, g/LW0.75) using the Cr2O3/in situ indigestibility technique. A completely randomized design was applied, using heifers as experimental units for DWG gains and VBI. At the beginning of the grazing, the BDM for Bb + Ca and Bb–considering the three periods-averaged, 3065 and 936 kg/ha, respectively. Crude protein content of C. argentea was around 20 %; and for Bb + Ca or Bb, ranged from 8.7 to 4.6 %. In either treatment, in situ DM degradability averaged 72.6 % (P ≥ 0.05), regardless of the botanical component type. Biomass DM intake was 83.02 (Bb + Ca) and 89.22 (Bb) g/LW0.75. The DWG gains (g/heifer) for Bb + Ca and Bb were (per period): 829 and 574 (first); 469 and 118 (second); and 534 and 508 (third). This study showed that the Bb + Ca association was better to improve the daily gain of F1 Holstein × Zebu heifers, as compared to Bb alone. Also, C. argentea associated to a low to medium-quality grass improved the nutritional value of the diet without affecting the biomass DM intake.