Recent progress in the assessment of mineral requirements of goats

Review: Update of nutritional requirements of goats for growth and pregnancy in hot environments

Goats play an important role in the agricultural business, providing valuable income sources through producing high-quality animal protein. They are widespread livestock for rural households due to their inherent resiliency, adaptability to many environments, and suitability in sustainable production systems. While goats are reared in highly diverse environments, a great portion of their population is reared in hot environments. Heat stress is known to affect goats' productive and reproductive performance negatively. However, goats can remarkably thrive in harsh conditions due to physiological, metabolic, and molecular adaptive mechanisms. In the face of it, in the last decades, the nutrition of goats, particularly their nutritional requirements, has received special attention. Research groups worldwide have dedicated their efforts to updating feeding systems for goats. Our objective was to present the recent findings on the energy and nutrient requirements of growing and pregnant goats in hot environments. Energy and protein requirements for the maintenance and growth of goats are influenced by sex and genotype only when mature weight is not considered in the models. Sex and genotype affect the efficiency of energy use for growth but do not affect the efficiency of protein use. Major mineral requirements for maintenance and growth are not affected by sex, except for magnesium. However, the phosphorus, sodium, and potassium requirements of goats raised in hot environments differ from those in the feeding systems. This difference may be related to the adaptation mechanisms goats employ to cope with the hot environmental conditions. Regarding requirements for pregnancy, there was no effect of days of pregnancy on the energy or protein requirements. The efficiency of metabolizable energy utilization for pregnancy increased with the progress of pregnancy. Mineral accretion for pregnancy differs between single and twin pregnancies and, irrespective of pregnancy type, the mineral requirements increase as pregnancy progresses. The differences between the estimated dietary requirements of goats raised in hot environments and the most widely adopted feeding systems suggest that these goats may be using energy and nutrients to cope with heat stress and other stressors associated with hot environments. The recent findings on energy, protein, and mineral requirements of growing and pregnant goats can be an important resource of information for enhancing feeding systems worldwide.

Iodine content in goat and sheep milk related to herd size, seasonality, farming practice and breed effect

Iodine is a milk micronutrient whose concentration is highly variable and depends on several factors. The aim of this work was to monitor the prevailing concentration of iodine in raw goat (n = 71) and sheep (n = 68) milk from farms in the Czech Republic, to assess the variation in iodine levels and evaluate them with farming practices, herd size, breed and season. Iodine was determined by a spectrophotometric method according to Sandell-Kolthoff. The mean prevailing iodine concentration in goat and sheep milk was 249.73 and 264.21 μg/L, respectively. In addition to inter-species variability, we found statistically significant differences depending on the both sheep and goat herd size. The differences between conventional and organic farming were relatively minor and without statistical significance.

An investigation on chemical/mineral compositions, ruminal microbial fermentation, and feeding value of some leaves as alternative forages for finishing goats during the dry season

Finding new fodder resources with moderate to high nutritional value that are cheaper and available is one of the most challenges in livestock industries. Hence, the nutritive value of some tree leaves (quince, pear, olive, mirabelle plum, greengage, sour cherry, and persimmon) was investigated by different laboratories and in vitro methods. Also, partial substitution of alfalfa and corn silage (50%) with these leaves was investigated using forty-eight goats in a randomized complete block design in vivo. Highest total phenol and tannin contents were obtained in quince (p < 0.001). Greengage (146.37 g/kg DM) and persimmon (136.96 g/kg DM) exhibited the highest crude protein, respectively (p < 0.001). Calcium content (19.82 g/kg DM) was highest in persimmon leaves (p < 0.001). Greengage (66.07 mmol/L) and mirabelle plum (65.58 mmol/L) produced more total volatile fatty acids in the culture medium, respectively (p < 0.001). Potential gas production ranged from 39.65 mL for pear to 55.32 mL mirabelle plum. Sour cherry had the highest acid-base buffering capacity (183.73 mEq × 10^-3, p < 0.001). Highest dry matter intake (1087 g/day) and crude protein digestibility (70.80 %) were observed in diets containing greengage (p < 0.001). Total antioxidant capacity of serum increased when olive, quince, and persimmon were considered in goats feeding (p < 0.001). Although all studied leaves can be fed in diets of goats without deleterious effects on performance, serum, and hematology parameters, in vivo and in vitro results indicated that greengage in terms of nutritive value was superior to other studied leaves.

Effect of Slow-Release Pellets of Selenium and Iodine on Performance and Some Blood Metabolites of Pregnant Moghani Ewes and Their Lambs

The need for minerals during pregnancy in mammals increases by progress of gestation due to embryo development. Therefore, the supply of trace minerals for pregnant ewes in late pregnancy may be of vital importance. The present study was carried out to evaluate the effect of selenium and iodine release slowly on the performance and some blood parameters of pregnant ewes and their lambs. Experiments were performed on 40 pregnant ewes from 3 to 4 years old in the last month of pregnancy with a weighing average of 52 ± 5 kg and a factorial experiment (2 × 2) in a completely randomized design with 4 treatments and 10 replicates used for 120 days (30 days before and 90 days after parturition of ewes). Experimental treatments were containing the following: (1) control, (2) ewe receiving bolus containing iodine, (3) ewe receiving bolus containing iodine and selenium, and (4) ewe receiving bolus containing selenium. One month before the expected birth date, the pellets will be fed to each of the livestock by bolus gun. During the test period, ewes will not receive any other mineral supplements and will be kept in a group in a herd. Ewes were blood sampled at 10 days prepartum and 30 and 60 days postpartum. The results showed that body weight on birth and weaning of lambs and average daily gain of lambs were highest in bloused animals that were related to the slow-release selenium tablet lambs (P < 0.05). Lambs born to mothers receiving 0.3 mg day^-1 of selenium per day had a keratin phosphokinase concentration of T₄ concentration and T₄ to T₃ lower than that of zero selenium (P < 0.05). Daily gain, glutathione peroxidase activity, and T₄ concentration at iodine 0.4 mg day^-1 were significantly higher than iodine level (P < 0.05). The adding of slow- release pellets of iodine and selenium improved the immune system.

Relationship between true digestibility of dietary phosphorus and gastrointestinal bacteria of goats

The present research was conducted to evaluate the connection between the true digestibility of Phosphorus (TDP) in diet and bacterial community structure in the gastrointestinal tract (GIT) of goats. Twenty-eight Nubian goats were chosen and metabolic experiment was conducted to analyze TDP of research animals. Eight goats were grouped into the high digestibility of phosphorus (HP) phenotype, and another 8 were grouped into the low digestibility of phosphorus (LP) phenotype. And from the rumen, abomasum, jejunim, cecum and colon content of the goats, bacterial 16S rRNA gene amplicons were sequenced. In the rumen 239 genera belonging to 23 phyla, in abomasum 319 genera belonging to 30 phyla, in jejunum 248 genera belonging to 36 phyla, in colon 248 genera belonging to 25 phyla and in cecum 246 genera belonging to 23 phyla were noticed. In addition, there was a significant correlation between the TDP and the abundance of Ruminococcaceae_UCG-010, Ruminococcus_2, Ruminococcaceae_UCG-014, Selenomonas_1 and Prevotella in the rumen, Lachnospiraceae_ND3007_group, Saccharofermentans, Ruminococcus_1, Ruminococcaceae_UCG-014, Lachnospiraceae_XPB1014_group and Desulfovibrio in the abomasum, Prevotella, Clostridium_sensu_stricto_1, Fibrobacter, Desulfovibrio and Ruminococcus_2 in the jejunum, Ruminococcaceae_UCG-014 in the colon, and Desulfovibrio in the cecum. Present research trial recommended that the community of gastrointestinal microbiota is a factor affecting TDP in goats.

Relationship between the True Digestibility of Dietary Calcium and Gastrointestinal Microorganisms in Goats

Simple Summary

The specific enzymes secreted by microorganisms in the gastrointestinal tract (GIT) of ruminants, such as phytase, can catalyze the decomposition of calcium compounds (e.g., phytic acid) and release bound calcium for the absorption of animals. Therefore, we speculate that gastrointestinal microbes could be a factor affecting digestion and absorption of dietary calcium. However, little related research has been reported. In the present study, we found that the true digestibility of calcium (TDC) in goats is related to gastrointestinal bacteria. Some gastro-intestinal bacteria, such as ruminal Prevotella, were beneficial for true host digestibility of dietary calcium.

Abstract

The current study was performed to examine the relationship between the true digestibility of calcium (TDC) in the diet and bacterial community structure in the gastrointestinal tract (GIT) of goats. Twenty-six Nubian healthy female goats were selected as experimental animals, and their TDC was determined using metabolic experiments. Eight goats were grouped into the high digestibility of Calcium (HC) phenotype, and another eight were grouped into the low digestibility of Calcium (LC) phenotype. Their bacterial 16S rRNA gene amplicons from the rumen, abomasum, jejunum, cecum, and colon contents were sequenced using next-generation high-throughput sequencing technology. In the rumen, 239 genera belonging to 23 phyla, 319 genera belonging to 30 phyla in the abomasum, 248 genera belonging to 36 phyla in the jejunum, 248 genera belonging to 25 phyla in the colon and 246 genera belonging to 23 phyla in the cecum were detected. In addition, there was a significant correlation between the TDC and the relative abundance of Candidatus_Saccharimonas, Christensenellaceae_R-7_group, Mogibacterium, Prevotella_1, Prevotella_UCG_004, Ruminococcus_2, Saccharibacteria in the rumen, Eubacterium_coprostanoligens_group, Lachnospiraceae_ND3007_group, Lachnospiraceae_NK3A20_group, p-1088-a5_gut_group, and Planctomycetes in the abomasum, Butyrivibrio in the cecum, and Fibrobacter in the cecum were observed. This study suggests an association of GIT microbial communities as a factor influencing TDC in goats.

Net micromineral requirements for maintenance and growth of ewe lambs at the latter fattening period

OBJECTIVE

The objective of this study was to investigate the net micromineral (Cu, Fe, Mn, Zn) requirements for maintenance and growth of Dorper×Jinzhong crossbred ewe lambs at their latter fattening period.

METHODS

Thirty 1/2 Dorper × 1/2 Jinzhong crossed F1 ewe lambs (35±0.5 kg of body weight [BW]) were used and divided into five groups in a randomized design for a comparative slaughter trial. At the beginning of the experiment, six lambs were randomly selected and slaughtered at 35 kg BW to determine their initial body composition. When their BWs reached 43 kg, another six lambs fed ad libitum were slaughtered to serve as an intermediate slaughter group. The retained eighteen lambs were randomly distributed into three groups and offered one type of feed at 100%, 65%, and 40% of the ad libitum intake. When the lambs fed ad libitum reached a BW of 50 kg, the three groups were slaughtered. The body composition (muscle, fat, bone, blood with viscera, skin, and wool) were weighted, ground, mixed, and subsampled for mineral content analysis.

RESULTS

The net maintenance requirements of Cu, Fe, Mn, and Zn were 0.017, 0.160, 0.004, and 0.067 mg/kg BW/d, respectively, and the net growth requirements per 100 grams of average daily gain ranged from 0.48 to 0.51 mg of Cu, 2.63 to 2.17 mg of Fe, 0.12 to 0.15 mg of Mn, and 2.07 to 2.00 mg of Zn, respectively, for Dorper × Jinzhong crossed ewes from 35 to 50 kg BW.

CONCLUSION

Our results suggest that the micromineral requirements for both maintenance and growth of Dorper × Jinzhong crossbred ewe lambs were quite different from the recommendations of NRC (2007), except for Zn.

Effects of Sodium Selenite, L-Selenomethionine, and Selenium Nanoparticles During Late Pregnancy on Selenium, Zinc, Copper, and Iron Concentrations in Khalkhali Goats and Their Kids

The objective of this study was to evaluate the effect of organic, inorganic, and selenium nanoparticle supplements at the final stage of pregnancy on selenium, zinc, copper, and iron concentrations of goats and placental, colostrum, and milk transfer of these trace minerals from goats to their kids. Forty pregnant Khalkhali goats (30 ± 5 kg) were randomly allocated to four treatments including (1) no supplement (control), 0.6 mg Se head^-1 day^-1 of selenomethionine (SM), 0.6 mg Se head^-1 day^-1 of selenium nanoparticles (SN), and 0.6 mg Se head^-1 day^-1 of sodium selenite (SS), from 4 weeks before the expected day of delivery to delivery day. Blood samples were taken from the goats 4 weeks before the expected day of delivery and on the kidding day. Colostrum samples were collected from the goats immediately after kidding. Instantly after delivery, newborn kids were taken apart from their dams and their blood samples were collected from the jugular vein, before they drank their first colostrums and at 7, 14, 21, and 28 after birthday. The results demonstrated that the whole blood and serum Se concentration was greater in Se-supplemented goats compared with the control (P < 0.05). The total Se content of the whole blood and serum was higher in SN than in SM (P < 0.05) and SS goats (P < 0.05). At birth, the whole blood and serum concentration of Se was decreased (P < 0.05) in kids of SN-treated goats contrasted with the control ones (P < 0.05). The copper content of goats and their kids in treated goats was greater compared with control goats except for SN treated, which was decreased (P < 0.05). It was totally vice versa with Zn content trend in the whole blood, serum, and colostrum (P < 0.05), which was also concomitant with an increase in Fe content of kids of supplemented goats at birth and first week of life (P < 0.05). These results seem to indicate a higher efficacy of placental and colostral transfer of Se into kids of SM-treated goats when contrasted with either receiving comparable doses of SN or SS. It could be concluded that Se supplementation can affect and correlate with Cu, Zn, and Fe levels, and this effect depends a lot on the chemical or physical variety of Se supplementation.

Multiple injections of vitamin E and selenium improved the reproductive performance of estrus-synchronized Awassi ewes

The aim of the current study was to investigate the effects of injecting estrus-synchronized ewes with vitamin E and selenium (Se) on their reproductive performance. Awassi ewes (n = 74) were randomly assigned into one of two groups. Group one (control, n = 36) did not receive vitamin E/Se injections, and group two (vitamin E/Se, n = 38) received 13.6-mg/kg BW of vitamin E plus 0.045-mg/kg BW of Se. Concurrent with estrus-synchronization program, vitamin E/Se injections were given at the time of insertion, withdrawal, and 19 days after withdrawal of intravaginal sponges. At all injection times, serum samples were collected (20 ewes per group) to measure Se contents. Pregnancy rates were evaluated by progesterone assay and by ultrasonography, respectively, at days 19 and 40 after sponge removal. Lambing rate, singles and twins%, sex ratio (M:F), and birth weight were recorded at lambing. Vitamin E/Se injections did not affect (P > 0.25) BW at lambing or BW change of ewes from breeding to lambing. Vitamin E/Se injections tended (P = 0.08) to decrease total pregnancy losses from 44.8 to 24.3%, subsequently, injections positively improved (P < 0.05) pregnancy rates determined by progesterone assay (from 80.6 to 97.4%) and ultrasonography (from 63.9 to 86.8%). Although overall fertility was not affected, vitamin E/Se injections markedly increased the percentage of ewes that lambed after only one service from 64.0 to 93.3%. Singles and twins%, lamb sex ratio, and birth weight of lambs were not affected (P > 0.20) by vitamin E/Se injections. Under conditions of our study, multiple injections of vitamin E/Se improved the reproductive performance of estrus-synchronized ewes.

Sex effects on macromineral requirements for growth in Saanen goats: A meta-analysis

The aim of this study was to investigate the effects of sex on the net requirements of growth for Ca (NCa), P (NP), Na (NNa), K (NK), and Mg (NMg) in Saanen goats from 5 to 45 kg BW, with or without consideration of the degree of maturity. A database containing 209 individual records for Saanen goats (69 castrated males, 71 intact males, and 69 females) was generated from 6 comparative slaughter studies. Total amounts of Ca, P, Na, K, and Mg in the body were fitted to logarithmized allometric equations using empty BW (EBW) or degree of maturity (EBW/mature EBW) as regressors. The equations were fitted using a mixed model, where sex was considered a fixed effect and study was considered a random effect. Net requirements were estimated by the first derivative of the logarithmized allometric equations. Then, a Monte Carlo simulation was used to assess the uncertainty of calculated net requirement values. Without considering the degree of maturity, sex did not affect NCa, NP, and NNa ( > 0.10). Conversely, considering the degree of maturity, NCa and NP of intact males were 5% and 2%, respectively, greater than those of castrated males and females ( < 0.01), and NNa of males (castrated and intact) was 6% greater than that of females ( < 0.01). Regardless of approach used, NCa and NP remained constant, whereas NNa decreased by 32% as BW ranged from 5 to 45 kg. Without considering the degree of maturity, NMg of castrated and intact males were 8% and 18% greater than that of female goats ( = 0.054), respectively. Hereof NMg of castrated and intact males increased by 8% and 15%, respectively, whereas that of females decreased by 8% as BW ranged from 5 to 45 kg. Considering the degree of maturity, NMg of castrated and intact males were 7% and 17% greater than that of female goats ( = 0.054), respectively. In this regard, NMg of castrated and intact males increased 8% and 16%, respectively, whereas that of females decreased by 7% from 5 to 45 kg BW. Both approaches showed that, regardless of sex ( > 0.10), NK decreased by 26% (i.e., without considering the maturity degree) or 27% (i.e., considering the degree of maturity) from 5 to 45 kg BW. Therefore, the consideration of maturity stage highlights differences across sexes in the net macromineral requirements for growth in goats. Elucidation of sex effects on macromineral requirements for growth may be useful for improving the accuracy of recommendations for mineral requirements for dairy goats.

Nutritional quality of kermes oak (<i>Quercus coccifera</i> L.) acorns as affected by altitude in a typical Mediterranean area

Abstract. The impact of altitudinal zone on the nutritional quality of kermes oak (Quercus coccifera L.) acorns was assessed in Xirovouni Mountain shrublands in northwestern Greece. Whole acorns were collected during autumn 2011 from 15 sites located at three altitudinal zones (i.e. lower, middle, upper). Kermes oak acorn samples were manually separated into kernel and hull and analysed for chemical composition (crude protein, CP; neutral detergent fibre, NDF; acid detergent fibre, ADF; lignin), in vitro dry matter (DM) digestibility (IVDMD), in vitro NDF digestibility (IVNDFD), digestible energy (DE), and minerals (i.e. Ca, P, K, Mg, Mn, Fe, Zn, Cu). Altitude had a negative correlation with CP, IVDMD, and IVNDFD and positively correlated to cell wall contents in both kernel and hull. Acorns growing under higher temperatures (at lower altitude) have more digestible cell wall compared to acorns growing under lower temperatures (at higher altitude) due to increased CP content and decreased cell wall content. It seems that environmental factors affect the nutritional value of acorns. Thus, goat farmers should take this into account when collecting acorns to feed their animals.

Net mineral requirements of dairy goats during pregnancy

Mineral requirements of pregnant dairy goats are still not well defined; therefore, we investigated the net Ca, P, Mg, Na and K requirements for pregnancy and for maintenance during pregnancy in two separate experiments. Experiment 1 was performed to estimate the net Ca, P, Mg, Na and K requirements in goats carrying single or twin fetuses from 50 to 140 days of pregnancy (DOP). The net mineral requirements for pregnancy were determined by measuring mineral deposition in gravid uterus and mammary gland after comparative slaughter. In total, 57 dairy goats of two breeds (Oberhasli or Saanen), in their third or fourth parturition, were randomly assigned to groups based on litter size (single or twin) and day of slaughter (50, 80, 110 and 140 DOP) in a fully factorial design. Net mineral accretion for pregnancy did not differ by goat breed. The total daily Ca, P, Mg, Na and K requirements for pregnancy were greatest in goats carrying twins (P<0.05), and the requirements increased as pregnancy progressed. Experiment 2 was performed to estimate net Ca, P, Mg, Na and K requirements for dairy goat maintenance during pregnancy. In total, 58 dairy goats (Oberhasli and Saanen) carrying twin fetuses were assigned to groups based on slaughter day (80, 110 and 140 DOP) and feed restriction (ad libitum, 20% and 40% feed restriction) in a randomized block design. The net Ca, P and Mg requirements for maintenance did not vary by breed or over the course of pregnancy. The daily net requirements of Ca, P and Mg for maintenance were 60.4, 31.1 and 2.42 mg/kg live BW (LBW), respectively. The daily net Na requirement for maintenance was greater in Saanen goats (11.8 mg/kg LBW) than in Oberhasli goats (8.96 mg/kg LBW; P<0.05). Daily net K requirements increased as pregnancy progressed from 8.73 to 15.4 mg/kg LBW (P<0.01). The findings of this study will guide design of diets with adequate mineral content for pregnant goats throughout their pregnancy.

A comparison between different concentrations and sources of cobalt in goat kid nutrition

There have been extensive studies in sheep and cattle considering cobalt (Co) supplementation and its effects on vitamin B12 concentrations in the body. However, there are limited studies on goats. The aim of this study was to compare two different sources of Co (sulfate v. glucoheptonate) at two different concentrations (0.25 and 0.5 mg/kg dry matter) in goat kid nutrition, and to evaluate the effects of these supplements on performance, serum vitamin B12, blood biochemistry and rumen volatile fatty acids. For this purpose, 30 weaned male goat kids were randomly allotted to five treatments. Serum vitamin B12 increased during the trial in the Co-supplemented groups. Co supplementation increased serum glucose concentrations. On day 35, Co-supplemented groups had greater glucose concentrations compared with control. Propionic+iso-butyric acid concentrations increased only in the 0.5 mg Co glucoheptonate treatment (P<0.05). Our results suggest that, despite the two sources of Co proving mostly similar, the main advantage of Co glucoheptonate compared with Co sulfate was in the ruminal synthesis of vitamin B12. However, although providing Co at National Research Council recommendation levels maintained vitamin B12 above or at normal concentrations, Co supplementation of the Co sufficient basal diet increased vitamin B12 and glucose concentrations.

Geophagic behavior in the mountain goat (Oreamnos americanus): support for meeting metabolic demands

Geophagy, the intentional consumption of earth or earth matter, occurs across taxa. Nutrient and mineral supplementation is most commonly cited to explain its adaptive benefits; yet many specific hypotheses exist. Previous research on mountain goats (Oreamnos americanus (Blainville, 1816)) broadly supports nutrient supplementation as the adaptive benefit of geophagy. Here, we use data from an undisturbed population of mountain goats inhabiting a geologically distinct coastal mountain range in southwestern British Columbia to test the hypothesis that geophagic behavior is a proximate mechanism for nutrient supplementation to meet metabolic demands. Our population, observed for over 30 consecutive years, returned each year with high fidelity to the same geophagic lick sites. Logistic regression demonstrated an overall effect of sodium and phosphorus, but not magnesium and calcium, on lick preferences. These data, in conjunction with field observations, provide support for the hypothesis that geophagy provides nutrient supplementation and that geophagy may be an obligate behavior to meet necessary metabolic demands within this population. The implications of our results suggest the necessity to preserve historically important habitats that may be necessary for population health.

Effects of organic and inorganic selenium supplementation during late pregnancy on colostrum and serum Se status, performance and passive immunity in Merghoz goats

This study was conducted to determine the effects of organic and inorganic selenium (Se) supplementation during late pregnancy on serum Se status, colostrum, performance and passive immunity in Merghoz goats in Iran. Thirty Merghoz goats (30 ± 3 kg) were given the same basal diet containing 0.11 mg Se/kg DM and were randomly allocated to one of three dietary treatments in a randomised complete block design. Four weeks before the expected kidding, the basal diets were supplemented with 0 (control), 0.3 mg Se/head.day in the form of L-selenomethionin (Se-Met) and 0.3 mg Se/head.day in the form of sodium selenite. Blood samples were collected from the goats in three phases: (1) a couple of days before starting the supplementation; (2) before the expected kidding; and (3) on the day of kidding. Blood samples were also taken from the newborn kids from the jugular vein at birth and 7 days of age. The serum Se and immunoglobulin G (IgG) concentrations, the white blood cells (WBC) and differential leukocyte counts were measured. The reproductive parameters such as the number of kids born per kidding, total weight of kids born per goat mating, the pregnancy period and kid birthweights were determined. The results indicated that the serum Se concentration increased in supplemented goats compared with controls. The Se concentrations also significantly increased in the colostrum of treated goats (P < 0.05). Similarly, serum Se concentrations in kids of treated goats were increased at birth. On the other hand, colostrum and daily milk production were not affected by Se supplementation. Likewise, the change in the mean serum IgG levels was not different among goats and kids (P > 0.05). However, the WBC, neutrophil and lymphocyte counts were higher in the kids of goats in the Se-Met group compared with the control group on the day of birth and 7 days of age (P < 0.05). It seemed that Se-Met could have influenced the lamb’s immunity at birth and 7 days of age. By contrast, selenite has not affected the performance and passive immunity in Merghoz goats.

Macromineral requirements for the maintenance and growth of Boer crossbred kids

Advances in mineral nutrition of goats have been made during the last decade, especially in our understanding of Ca and P requirements. However, few studies have focused on the mineral requirements of crossbred Boer goats in their growth phase. Our objective for this study was to determine the macromineral (Ca, P, Mg, K, and Na) requirements for the maintenance and growth of intact, male three-fourths Boer × one-fourth Saanen kids (n = 34; 20.5 ± 0.24 kg of initial BW). Two trials were conducted: 1 for maintenance and 1 for growth requirements. In the maintenance trial, 28 kids were used. The baseline (BL) group consisted of 7 randomly selected kids averaging 21.2 ± 0.36 kg BW and 122 d old. The remaining kids (n = 21; age 168 ± 5 d) were randomly allocated into 7 slaughter groups (blocks) including 3 animals distributed among 3 amounts of DMI (treatments: ad libitum and restricted to 70 or 40% of ad libitum intake). Animals in a group were slaughtered when the ad libitum-treatment kid in the block reached 35 kg BW. The BL and ad libitum-fed groups in the maintenance trial were also part of the growth trial. Therefore, in the growth trial, 20 kids fed for ad libitum intake were used as follows: 7 kids slaughtered at 21.2 ± 0.36 kg BW (BL), 6 kids slaughtered at 28.2 ± 0.39 kg BW (intermediate slaughter), and 7 kids slaughtered at 35.6 ± 0.36 kg BW. Empty whole bodies of the kids (head + feet, hide, internal organs + blood, and carcass) were weighed, ground, mixed, and subsampled for chemical analyses. Daily maintenance requirements, calculated using the comparative slaughter technique (P < 0.001), were estimated as 32.3 ± 1.1 mg Ca, 30.8 ± 1.2 mg P, 1.31 ± 0.5 mg Mg, 8.41 ± 3.0 mg K, and 5.14 ± 1.0 mg Na/kg of empty BW (EBW). Net requirements for growth increased from 6.2 to 6.6 g Ca, 5.3 to 5.4 g P, and 0.29 to 0.30 g Mg and decreased from 1.20 to 1.07 g K and 0.65 to 0.59 g Na/kg of EBW gain for kids from 20 to 35 kg BW. This study indicated that the net mineral requirements for Boer crossbred goat kids may be different from those of purebred or other genotypes, and more data are needed for goats in general.

Evaluation of the mineral status of two ecosystems for sustainable goat rearing in the iberian peninsula

The mineral status in two ecosystems typical of the Iberian Peninsula was evaluated. Ecosystem I was formed by forests and ecosystem II by hilly areas. The levels of calcium, phosphorus, magnesium, iron, copper, zinc and selenium in soils, rations and serum were measured. The concentratons of iron, copper, zinc and selenium were also checked in liver. Ecosystem I showed higher values of every mineral, except for phosphorus. Seasonal differences were recorded for rations and serum, with higher values in spring. The rations produced by both ecosystems met the mineral requirements of goats in lactation. Thus, both ecosystems are suitable for the development of an ecological goat farming system. However, extra supply of minerals, particularly calcium, may be needed in the maximum productions periods.

An evaluation of the effect of clotting on the recovery of copper from caprine blood

In the goat, diagnosis of copper (Cu) deficiency is often based on measurement of Cu in serum or plasma. Previous research in cattle and sheep has shown that these values are not interchangeable, but data for goats have not been published. Paired serum and heparinised plasma samples taken from 119 goats in eight herds were tested for Cu concentration. Plasma and serum Cu were significantly correlated (r=0.95). On average serum Cu was 3.5 μmol/L lower than plasma Cu, but this difference was related to Cu status (r=0.45). Mean serum Cu concentration was 83% of plasma Cu, with the 95% limits of agreement ranging from 66% to 100%. Similar to cattle and sheep, individual variability in Cu loss during clotting is too great for serum Cu to be used as a measure of Cu status in goats.

The influence of supplementation of different forms of zinc in goats on the zinc concentration in blood plasma and milk

The aim of the experiment was to study zinc concentration in goat's milk during a short-term oral supplementation of three organic and one inorganic form of zinc and the influence of Zn supplementation on the concentration of Zn and Cu in blood plasma. The experiment involved 31 lactating goats. The group C was the control, group L received zinc lactate, group A received zinc chelate, group T received amino acid-polypeptidic complex with zinc, and group O received zinc oxide. Zinc preparations were administered orally in 500 mg Zn per animal for 28 days. In the course of the experiment, Zn concentration in plasma increased significantly in all experimental groups and in the control group was unchanged. The concentration of zinc in milk during the experiment fluctuated in individual groups, but there were no significant differences between groups. After 28 days of Zn supplementation, Zn concentration in milk of goats was similar as at the start of the experiment in all groups. According to our results, the supplementation of different forms of zinc did not influence the concentration of Zn in milk, but significantly influenced the Zn concentration in blood plasma. The efficiency of different organic and inorganic forms of zinc was similar.

Monitoring of changes in selenium concentration in goat milk during short-term supplementation of various forms of selenium

The goal of the experiment was to monitor the changes in the selenium concentration in goat milk during short-term oral supplementation of three different forms of selenium. The experiment involved 24 lactating goats of white shorthaired breed. Group C was the control; group S received selenium in the form of selenium-enriched yeast, group L in the form of lactate, and group B in the form of proteinate. Individual selenium preparations were administered individually orally in 250 microg Se dose per animal for 20 days. After the beginning of selenium supplementation, the selenium concentration in milk during the first 5 days grew gradually in group S. Between days 7 and 20 of Se supplementation, the mean Se concentrations in milk in groups were 12.53 +/- 3.69 microg l(-1) (C), 25.90 +/- 6.30 microg l(-1) (S), 13.14 +/- 3.54 microg l(-1) (L), 11.70 +/- 3.69 microg l(-1) (B). Differences between group S and other groups (C, B, L) were highly significant (p < 0.0001). Based on our results, selenium in the form of lactate and proteinate was excreted into the milk similarly, but selenium in the form of yeast, which contains high amount of selenomethionine, was excreted by milk in the highest amounts.

The content of protein, fibre and minerals of leaves of selected Acacia species indigenous to north-western Tanzania

Browse tree leaves of six species of Acacia (A. angustissima L., A. drepanolobium L., A. nilotica L., A. polyacantha L., A. senegal L., A. tortilis L.) were screened for chemical composition, including minerals and trace elements. Crude protein (CP) varied among the species from 145 (A. senegal) to 229 g/kg DM (A. angustissima). The species had moderate to high levels of minerals. The concentrations of Ca, P, Mg and S varied among the species from 14.6-31.5, 3.5-4.9, 1.4-3.0 and 1.7-2.8 g/kg DM, respectively. The forages showed relatively low concentrations of trace elements. Content of trace elements varied among the species from 4.5-23.8, 99.4-173.6, 146.2-432, 41.0-90.1, 10.9-22.2 and 0.05-0.65 mg/kg DM for Cu, Mo, Fe, Mn, Zn and Co, respectively. All leaves of browse species would meet the normal requirements for Ca, P, Mg and S in ruminants, although some species had higher levels of Ca than tabulated mineral requirements in livestock. Assayed Cu, Mn, Zn and Co would satisfy the lower range of recommended requirements of trace elements depending on their bioavailability. Therefore, browse leaves from Acacias could form good sources of CP and mineral supplements to ruminants.

Effect of selenium-vitamin E injection in selenium-deficient dairy goats and kids on the Mexican plateau

Three experiments were carried out to determine the optimum selenium-vitamin E injection level to maintain acceptable blood selenium (Se) status of does and kids, as well as to determine the relation of that status to mortality rates in kids. In experiment 1, 238 goats were assigned to one of three groups during the mating period: A1-control, A2- 0.06mgSe+0.8IU vitE/kgBW and A3-0.125mgSe+1.7IU vitE/kgBW. No differences (P>.05) for fertility and prolificacy were observed among the groups. Blood Se concentration did not differ among Se-vit E groups and control group before injection, and both groups showed Se deficient condition. There was a trend (P<.05, 32%) to increase Se blood level 60 days post-treatment, but difference was not observed between A2 and control groups, while difference (P<.05; 103%) was observed between A1 and A2 groups vs high Se injection (A3 group). In experiment 2, 48 goats were divided into four groups: B1- control, B2- 0.125mgSe+1.7IU vitE/kgBW, B3- 0.25mgSe+3.4IU vitE/kgBW and B4- 0.31mgSe+4.2IU vitE/kgBW. The B4 group reached the highest concentration at the third month after injection (0.11 ppm), then started to decline after 100 days, reaching a value slightly higher than B2 and B3 on the 135th day of pregnancy. Results of B2 and B3 groups were slightly higher that those of B1 (P<0.05). In experiment 3, 194 kids (3 to 7 days postpartum) born from Se-deficient goats were used to compare the effectiveness of Se injection. They were divided into three groups: C1- control, C2- 0.3mgSe+4.2IU vit E/kg BW and C3- 0.6mgSe+8.4IU vit E/kg BW. C1 showed the highest percentage of mortality (60%) as compared to treated Se groups, that scored equal percentage of deaths (22% averaged). The concentration of Se in blood, on day 20th after the onset of the treatment rapidly increased, according with level of Se injection. The 0.3mgSe/kgBW Se injection increased the blood Se concentration in pregnant goats and it was effective to prevent white muscle disease lesions, besides enhancing the survival of kids until weaning.

Lactation response and nitrogen, calcium, and phosphorus utilization of dairy goats differing by the genotype for alpha S1-casein in milk, and fed diets varying in crude protein concentration

Twenty-four dairy goats were used in a preliminary trial to evaluate the effect of the genotype for alpha S1-casein (alpha S1-CN) in milk [homozygous variant A/A (n = 12) or F/F (n = 12)] on milk yield and composition for 2 wk from kidding. After this period, the main trial aimed at determining the effects of the genotype for alpha S1-CN in milk, the dietary crude protein concentration on milk yield and composition, and utilization of N, Ca and P. The goats within each genotype were allocated to a 3 x 3 Latin square for 14 wk with three crude protein concentrations in the total mixed ration (13.2, 16.8, and 19.8% of dry matter) and three periods (wk 3 to 6, wk 8 to 11, and wk 13 to 16 postpartum) as factors. Balances of N, Ca, and P were determined in the last week of each period. Two wk after kidding, the alpha S1-CN A/A goats had higher percentage and yield of protein and lower body weight than the alpha S1-CN F/F goats. During the main trial, yields of protein and fat, as well as percentages of fat and protein in milk were higher for the alpha S1-CN A/A goats than for the alpha S1-CN F/F goats, independent of dietary CP concentration and period. Efficiency of N digestion for milk N was higher for the alpha S1-CN A/A goats than for the alpha S1-CN F/F goats. Urinary N as a percentage of digested N, and total N excretion expressed relative to milk N were lower for the alpha S1-CN A/A goats than for the alpha S1-CN F/F goats. Neither the apparent absorption of calcium or phosphorus was affected by the genotype for alpha S1-CN. Goats fed the low crude protein diet had lower milk yield and lower yields of fat and protein than those fed the other diets. Increasing dietary crude protein concentration increased urinary N, milk N, and N excretion relative to milk N; it also decreased the efficiency of digested N for milk N. In conclusion, selection of goats with a genetically higher yield of casein and fed with diets formulated to reduce N excretion improves the cheese-making properties of goat milk and reduces concerns about N wastes in the environment.

Influence of calcium on the early steps of rotavirus infection

The structure of rotaviruses and many steps of their replication cycle depend on the concentration of calcium in the microenvironment. In this work, to learn about the role of calcium during the early steps of the infection, we characterized the effect of increasing the calcium concentration in the medium on the infectivity of rotaviruses. We found that a fivefold increase in the calcium concentration of the cell culture medium results in an increased viral titer in all rotavirus strains tested. The effect of this divalent ion seems to be mainly on the viral particle and not on the surface of the cell. Analysis of the intrinsic fluorescence spectra of purified triple-layered particles revealed that changes in the environment of tryptophan residues occurred as calcium concentration increased, suggesting that conformational changes in the viral particle might be responsible for the effect of this ion on the viral infectivity.

Effects of high copper supplements on performance, health, plasma copper and enzymes in goats

Six growing female Nubian goats (average BW=34.8+/-0.55kg, 7-8 months of age) were randomly assigned to either a basal diet (BD, 10-15ppm Cu/DM), or to medium Cu (MC, BD+50mgCu), or to high Cu (HC, BD+100mgCu) diets for 9 weeks. This level would cause Cu toxicity in sheep, but none occurred in the goats. Therefore, Cu supplementation was then increased to 150 and 300mg per head per day, for the following 14 weeks; to 300 and 600mg per head per day, for the next 8 weeks; and to 600 and 1200mg per head per day, for an additional 4 weeks, in the MC and HC group, respectively. Body weight and vital signs were recorded and blood samples collected at different time intervals. Hematological parameters, plasma Cu, sorbitol dehydrogenase (SDH), glutamic oxaloacetic transaminase (GOT), and gamma-glutamyl transferase (GGT) were determined. At the termination of the study, tissue Cu concentration in different organs was also determined. During first 23 weeks (<300mgCu per day) of the study there were no apparent signs of Cu toxicity. Cu supplementation at 600mg per head per day in young Nubian does, had no effect on respiration rate (RR), heart rate (HR), and decreased (P<0.05) rectal temperature (RT) in the HC group only. Leukocyte counts were positively correlated with Cu supplementation (r=+0.296, P<0.02) and negatively correlated (r=-0.254, P<0.05) with RT in the HC group. Plasma SDH increased (P<0.05) when Cu supplementation was >/=300mg per head per day, thus, SDH may serve as an early indicator of Cu toxicosis in goats. Increases (P<0.05) in GOT were noted when Cu intake was >/=600mg per head per day. Contrary to the results observed for SDH and GOT, feeding goats 50mgCu per day or more, resulted in an increased plasma GGT as compared to BD goats. Levels of SDH, GOT and GGT of the BD goats were within normal range. Plasma Cu was not indicative of Cu status of animals. Copper improved ADG by 28% at the 100-150ppm level in diet. No relationship between Cu intake and hair Cu was found in the present study. Highest concentration of Cu was found in liver, followed by duodenum, rumen and brain. Results of this study indicate that goats are more resistant to Cu toxicity than sheep. This is one of the first reports documenting significant differences in Cu requirements and tolerance between goats and sheep.