Influence of forage-to-concentrate ratios on intake, digestibility, chewing and milk production of dairy goats

Effect of forage to concentrate ratio on growth performance and feeding behavior of Thalli lambs

The objective of the study was to evaluate the effect of forage to concentrate ratio (F:C) on growth performance and feeding behavior of Thalli lambs. For this purpose, twenty-one male Thalli lambs with initial live body weight (26.30 ± 3.02 kg) were selected and divided into three experimental groups in a randomized complete block design. The experimental duration was 12 weeks. The experimental diets were F:C (100:0), F:C (80:20), and F:C (60:40). Alfalfa hay was used as forage source. Lambs fed F:C (60:40) and F:C (80:20) diets showed higher dry matter intake (DMI), total dry matter intake (TDMI), organic matter intake (OMI), weight gain, growth rate, better feed conversion ratio, and feed efficiency as compared to the lambs fed F:C (100:0) (P < 0.05). The results also showed that crude protein (CP), ether extract (EE), and total digestible nutrient (TDN) intake were maximum in F:C (60:40)-fed lambs (P < 0.05). However, higher crude fiber (CF), neutral detergent fiber (NDF), and acid detergent fiber (ADF) intakes were seen in the F:C (100:0)-fed lambs (P < 0.05). The results of nutrient digestibilities revealed the improved OM, DM, CP, and ADF digestibilities in lambs fed with F:C (60:40) and F:C (80:20) (P < 0.05). The digestibility of NDF and CF were not affected by the all-dietary treatments (P > 0.05). Behavior results explored that eating time, and chewing time was higher in F:C (100:0)-fed lambs (P < 0.05), while standing time, lying time, and abnormal behavior were increased in lambs fed with F:C (60:40) and F:C (80:20) (P < 0.05). Based on the results, it is concluded that the addition of concentrate at 20% and 40% improves growth performance and increases DMI, TDMI, OMI, and nutrient digestibility. However, standing time, lying time, and abnormal behavior increase by feeding of the 20% and 40% concentrate. Therefore, it is suggested that the concentrate should be supplied in restricted amounts to improve lambs' welfare and normal behavior without influencing their performance.

Effects of Breed and Stage of Lactation on Milk Fatty Acid Composition of Italian Goat Breeds

Fatty acid (FA) profile plays an important role on human health and on sensory quality of dairy products. There is few information about breed influence on milk FA profile of local goat breeds. This study aimed to characterize and compare the milk FA profile of 5 local endangered goat breeds (Garganica, Girgentana, Jonica, Maltese, and Mediterranean Red) and a cosmopolitan breed (Saanen) reared in the same farm during a complete lactation. A total of 252 milk samples were collected monthly from 42 goats (7 goats per breed) and analyzed for gross composition and FA profile. Individual FA was determined using gas-chromatography. Data were analyzed using a mixed model with repeated measures with breed and week of lactation as fixed effects. Results showed that the FA profile was significantly affected by week of lactation and only few FA by breed effect (p < 0.05). Overall, the main differences were found between Saanen and local breeds. This study contributed to the characterization of goat milk FA profile, and it may be of interest for the valorization of milk from local goat breeds which seem to have a healthier profile than milk of the cosmopolitan breed.

Nutritional and haemato-biochemical modulation in dairy goats during mid-pregnancy

The present study was conducted to assess the influence of mid-pregnancy on the nutrient utilization, haematological and blood biochemical profile in gravid goats. Sixteen indigenous non-descript does of approximately 3–4 years of age were randomly allotted to two equal groups (PREG and NPREG) of eight each based on individual BW. The goats of pregnant group (PREG) were synchronized, mated and were left for routine group feeding, care and management. They were brought to experiment just 60 days after mating along with the non-pregnant (NPREG) group; both the groups were offered basal diet comprised of concentrate mixture and wheat straw to meet their nutrient requirements. A metabolic trial of six day duration was conducted at 90 days after mating on all the experimental goats to assess the nutritional modulation along with any changes of haematological and blood biochemical parameters at mid pregnancy stages. The results revealed no variation in intake and digestibility of DM, OM and CP. However, the digestibility of NDF, ADF and hemicellulose was higher for PREG does as compared to NPREG control. The balance of nitrogen was positive and comparable between the groups. Blood haematobiochemical profile showed no significant influence of pregnancy on different blood metabolites except that of low serum urea. The serum variables representative of the liver function was within the normal range and were comparable between the groups. It is concluded that mid-pregnancy induces no perceptible nutritional modulation except for subtle improvements in fibre digestibility, and possibly protein utilization in dairy goats.

Effects of dietary forage-to-concentrate ratio on nutrient digestibility and enteric methane production in growing goats (Capra hircus hircus) and Sika deer (Cervus nippon hortulorum)

Objective

Two experiments were conducted to determine the effects of forage-to-concentrate (F:C) ratio on the nutrient digestibility and enteric methane (CH₄) emission in growing goats and Sika deer.

Methods

Three male growing goats (body weight [BW] = 19.0±0.7 kg) and three male growing deer (BW = 19.3±1.2 kg) were respectively allotted to a 3×3 Latin square design with an adaptation period of 7 d and a data collection period of 3 d. Respiration-metabolism chambers were used for measuring the enteric CH₄ emission. Treatments of low (25:75), moderate (50:50), and high (73:27) F:C ratios were given to both goats and Sika deer.

Results

Dry matter (DM) and organic matter (OM) digestibility decreased linearly with increasing F:C ratio in both goats and Sika deer. In both goats and Sika deer, the CH₄ emissions expressed as g/d, g/kg BW^0.75, % of gross energy intake, g/kg DM intake (DMI), and g/kg OM intake (OMI) decreased linearly as the F:C ratio increased, however, the CH₄ emissions expressed as g/kg digested DMI and OMI were not affected by the F:C ratio. Eight equations were derived for predicting the enteric CH₄ emission from goats and Sika deer. For goat, equation 1 was found to be of the highest accuracy: CH₄ (g/d) = 3.36+4.71×DMI (kg/d)−0.0036×neutral detergent fiber concentrate (NDFC, g/kg)+0.01563×dry matter digestibility (DMD, g/kg)−0.0108×neutral detergent fiber digestibility (NDFD, g/kg). For Sika deer, equation 5 was found to be of the highest accuracy: CH₄ (g/d) = 66.3+27.7×DMI (kg/d)−5.91×NDFC (g/kg)−7.11× DMD (g/kg)+0.0809×NDFD (g/kg).

Conclusion

Digested nutrient intake could be considered when determining the CH₄ generation factor in goats and Sika deer. Finally, the enteric CH₄ prediction model for goats and Sika deer were estimated.

Influence of forage: concentrate ratio and type of starch in the diet on feeding behaviour, dietary preferences, digestion, metabolism and performance of dairy goats in mid lactation

In a 12-week trial, 12 Alpine and 12 Saanen dairy goats in mid lactation were housed in individual stalls for behavioural, digestive and metabolic studies. Eight of them were fitted with ruminal cannulae. They were offered ad libitum four complete diets CR, CS, FR and FS (450 g dry matter (DM) per kg) in a 4✕4 Latin-square design. Forage: concentrate ratio was either low (C = 30: 70) or high (F = 55: 45) and starch source either rapidly (R, barley) or slowly (S, maize) degraded in the rumen.

Diet preferences were tested. DM intake, chewing activities and performance were determined. Ruminal pH and ammonia-nitrogen (NH3-N) concentrations were measured. Goats were also challenged intravenously with glucose (0·2 g/kg live weight) to assess glucose homeostasis.

CR was the most preferred diet. The level of intake differed according to the type of starch (2·2 kg DM per day of CR and FR and 2·0 kg DM per day of CS and FS). FS lowered ruminal pH significantly less than the other diets after the meal. Ruminal NH3-N concentrations were lower in goats given CR and CS than FR and FS. Goats’ resistance to a glucose challenge was not different among diets. Milk yield was 2·00, 1·85, 2·01, 1·85 kg/day on CR, CS, FR and FS respectively. Milk fat content decreased significantly with diets rich in concentrate (24 v. 26 g/kg milk) but milk protein content varied only a little.

In conclusion it appears that (1) higher forage: concentrate ratios were less preferred and decreased ruminal acidity but increased daily chewing, ruminal NH3-N and milk fat content; and (2) rapidly degraded starch increased intake, ruminal acidity and milk yield.

Use of dry citrus pulp or soybean hulls as a replacement for corn grain in energy and nitrogen partitioning, methane emissions, and milk performance in lactating Murciano-Granadina goats

The aim of this study was to assess the effect of substitution of dietary corn grain by dry citrus pulp or soybean hulls on energy and nitrogen partitioning, substrate oxidation, methane emission, and milk performance in dairy goats during midlactation. Twelve multiparous Murciano-Granadina goats of similar body weight (41.7 ± 2.8 kg) were split in 3 groups in an incomplete crossover design. One group of 4 goats was fed a mixed ration with 605 g/kg of dry matter of corn grain (CRG), another group replaced corn grain with dry citrus pulp (CTP), and the last with soybean hulls (SYH). The goats were allocated to individual metabolism cages. After 14 d of adaptation, feed intake, total fecal and urine output, and milk yield were recorded daily over a 5-d period. Then, gas exchange measurements were recorded by a mobile open-circuit indirect calorimetry system using a head box. Dry matter intake was similar for all 3 groups (1.53 kg/d, on average). Total replacement of the concentrate with fibrous by-products increased fiber apparent digestibility. The metabolizable energy intake was significantly greater for diet CRG than SYH (1,193 vs. 1,079 kJ/kg of BW⁰·⁷⁵, respectively), CTP showed an intermediate value. The heat production was higher for the fiber diet than starchy diet (908 vs. 843 kJ/kg of BW⁰·⁷⁵ for SYH and CRG, respectively). The efficiency of use of metabolizable energy for milk production obtained by regression was 0.59. Goats fed CTP and SYH diets produced similar CH₄ emissions (34.8 g/d, on average), significantly higher compared with goats fed the CRG diet (24.7 g/d). Goats of the 3 treatments were in negative energy balance, so the oxidation of fat was greater than for carbohydrates. No significant differences were observed for milk production (1.72 kg/d), and milk fat was significantly greater for a more fibrous diet compared with a starchy diet (6.57 vs. 4.95% in SYH and CRG, respectively).

Effects of the percentage of concentrate on rumen fermentation, nutrient digestibility, plasma metabolites, and milk composition in mid-lactation goats

The aim of this work was to study the effects of the dietary percentage of concentrate on patterns of intake, the evolution of rumen fermentation characteristics and plasma metabolites after a meal, nutrient digestibility, and milk production and composition in a medium-term trial in dairy goats. These effects have been well studied in dairy cattle but seldom in goats. Thirteen ruminally and duodenally cannulated dairy goats (95±4 d in milk) fed ad libitum were used in this study. Goats were assigned to 1 of 2 dietary treatments: high-concentrate (70% concentrate on dry matter basis) or a low-concentrate (35%) total mixed rations. The experiment was conducted over a period of 10 wk, including 3 wk of adaption to the diets. Patterns of intake, rumen fermentation characteristics, and plasma metabolites after a meal and fatty acids profile of milk fat were compared at the onset and at the end of the experiment. The increase in dietary percentage of concentrate decreased rumen pH, acetate to propionate ratio, ammonia-N concentration, and plasma urea concentration. The percentage of concentrate did not affect total volatile fatty acid concentrations. The high-concentrate diet increased the rate of intake during the morning meal at the onset of the experiment, whereas it decreased total dry matter intake and the rate of intake during the morning meal at the end of the experiment. The high-concentrate diet resulted in greater organic matter digestibility. Raw milk yield and protein yield were greater in goats fed the high-concentrate diet, whereas fat yield was not affected by dietary treatments. The milk fat content was lower in goats fed the high-concentrate diet. Proportions of the trans-C18:1 isomer relative to total fatty acids in milk were higher with the high-concentrate diet, but no modification of the proportion of total trans-C18:1 was detected, in particular no shift from trans-11 C18:1 to trans-10 C18:1 was observed. Further, the isomer trans-10,cis-12 C18:2 was not detected. Data from this study could be used for a new modeling approach or to improve existing models.

Diet selection and milk production and composition in Girgentana goats with different alpha s1-casein genotype

In goats, alpha s1-casein polymorphism is related to different rates of protein synthesis. Two genetic variants, A and F, have been identified as strong and weak alleles based on a production of 3.5 and 0.45 g/l of alpha s1-casein per allele. The aim of the trial was to test whether goats can select their diet as a function of their genetic aptitude to produce milk at different casein levels and whether this selection can influence milk production or composition. Two groups of 8 animals, homozygous for strong (AA) or weak (FF) alleles were housed in individual pens. Using a manger subdivided into five separate containers, the goats were offered daily for 3 weeks: 1.5 kg of alfalfa pelleted hay, 0.7 kg of whole barley, 0.7 kg of whole maize, 0.7 kg of whole faba bean and 0.7 kg of pelleted sunflower cake. Total dry matter intake was similar between groups and resulted in nutrient inputs much higher than requirements. On average, goats selected 86% of maize plus barley and only 46% of faba bean plus sunflower. Indeed, AA goats selected less faba bean compared with FF goats (37.2 v. 56.7% of the available amount; P=0.01); during week 2 and week 3 they significantly increased maize selection (respectively for week 2 and week 3: 94.9 and 99.1% v. 85.3 and 87.3%) thus increasing the ratio between the high-energy feeds and the high-protein feeds (2.41 v. 1.81, P=0.023). As for true protein, the high soluble fraction (B1) and the indigestible fraction (C) were lower in the diet selected by AA goats (respectively in AA and FF groups: B1, 7.85 v. 9.23% CP, P<0.01; C, 6.07 v. 6.30% CP, P<0.001); these diet characteristics can be associated with lower losses of protein. Milk production, being similar in AA and FF groups when goats were fed with a mixed diet, significantly increased in AA group, when free-choice feeding was given (mean productions: 1198 v. 800 g/d, P<0.01). Casein content was higher in AA group than in FF group (2.70 v. 2.40%, P<0.01) whereas milk urea was higher in FF group (59.7 v. 48.8 mg/dl, P<0.01). In conclusion, when the animals were free to select their diet, their higher genetic aptitude to produce casein seemed to adjust their energy and protein dietary input in qualitative terms, thus leading to an increase in milk production and a decrease in milk urea. These results seem to demonstrate that interactions probably occurred between genetic polymorphism at the alpha s1-casein locus, diet selection and the efficiency of nutrient transformation into milk.

Forage to concentrate ratio in Jonica breed goats: influence on lactation curve and milk composition

The aim of the work is to evaluate the effects of different forage to concentrate rations on milk yield, composition and renneting properties of milk of Jonica breed goats. Twenty-four Jonica goats received diets with forage to concentrate ratio of 35/65, 50/50 or 65/35, providing respectively a low, medium and high energy level. Goats were divided into three homogenous groups and confined in individual pens for 152 days to assess the daily feed intake and milk yield and composition. The main conclusions show that animal body weight did not change significantly with the increasing levels of forage, whereas significant differences (P<0.05) for daily dry matter intake were observed in relation to the evolution of lactation. Milk production was influenced (P<0.05) by dietary treatments and was higher in the diet with the greatest energy level. Forage to concentrate ratios did not significantly affect milk characteristics, milk renneting properties, initial production, rate of increase until reaching the peak and rate of decline after peak production. However, the day of peak production and peak production of goats were linearly reduced when the level of forage increased within the diet. In conclusion, the results indicate that both forage to concentrate ratio and energy level improve goat's production without influencing the milk composition.

The effect of hot season and nutrition on the oxidative status and metabolic profile in dairy goats during mid lactation

The aim of this study was to evaluate the effects of the hot season and nutrition on the oxidative status and metabolic profile of lactating goats during mid lactation. Twenty-four Red Syrian goats were allocated into three groups that were offered the following diets: natural pasture (P), pasture+500 g/h per day of concentrate (PC) and hay plus 500 g/h per day of concentrate (HC). Blood samples were taken in spring (85±7 days in milk (DIM)) and summer (120±7 DIM) and assayed for reactive oxygen metabolites (ROMs), α-tocopherol, glucose, triglycerides, cholesterol, non-esterified fatty acids, total protein, albumin and globulin concentrations and glutathione peroxidase (GHS-Px) and superoxide dismutase (SOD) activities. Milk yield and milk composition were also measured. SOD, GSH-Px and ROMs levels increased during summer when temperature humidity index values were high. The increase in ROMs in the PC and HC groups could be ascribed to the improved nutritional regime and to their higher production level. The markers of the oxidative status and of the metabolic profile measured in this study indicate that goats may have experienced moderate oxidative stress. It seems that, seasonal rather than nutritional factors have a more pronounced effect on oxidative status markers. Concentrate supplementation sustained milk yield and may represent a useful means to extend the lactation period in dairy goats during late spring and summer.

Strategies for increasing energy density of dry cow diets

The objective of this trial was to compare the effects of increasing dietary energy density from 1.51 to 1.65 Mcal/kg of dry matter (DM) by replacing forage with concentrate or by further increasing concentrate via the substitution of corn silage and alfalfa silage by a mixture of straw, starch, and soybean meal. Our hypothesis was that the latter diet would be more glucogenic while increasing rumen fill and be potentially desirable for transition cows. Nine far-off dry cows (greater than 3 wk before parturition at the end of the trial) were fed three diets: low energy diet, [LE, 1.51 Mcal/kg of DM, 14.0% crude protein (CP) and 35% nonfiber carbohydrates (NFC)], high energy diet, (HE, 1.65 Mcal/kg of DM, 13.9% CP and 39.5% NFC) and high energy diet, where a portion of alfalfa and corn silage was replaced by straw, soybean meal, and cornstarch (HES, 1.65 Mcal/kg of DM, 13.5% CP and 40.5% NFC). The experiment was a replicated 3 x 3 Latin square design with 21-d periods. Six cows from two squares were used to examine kinetics of DM disappearance from nylon bags suspended in the rumen. Two contrasts of interest were: LE versus HE, HES (effects of energy density) and HE versus HES (method of increasing energy density). Increasing energy density increased the potentially degradable (B) and decreased the undergradable (C) DM fractions of the diets. Because HES had greater B and a faster rate of degradation of fraction B (k), effective rumen degradable DM (ERDDM) was higher in HES compared to HE. Cows fed high energy diets had greater DM intake. No differences in DM intake were observed between HE and HES. Rumen volume or DM pool sizes were not affected by treatment. High energy diets increased total ruminal fluid volatile fatty acid concentration compared with LE. Propionate concentration was higher in cows fed high energy diets compared with cows fed LE. The partial replacement of alfalfa and corn silage by straw, soybean meal, and cornstarch further increased propionate concentration. The greatest increase in serum insulin concentration following feeding was observed in cows fed HE. Cows consuming high energy diets had lower plasma nonesterified fatty acids (NEFA) before and after feeding. The HES diet was less effective in decreasing plasma NEFA concentration after feeding compared to HE. In conclusion, increasing diet energy density of far-off dry cows positively affected DMI, ruminal propionate, serum insulin, and plasma NEFA. Increasing energy density with a blend of feeds that represent extremes in rates of carbohydrate fermentation may be a strategy to provide greater amounts of glucogenic precursors. Applicability of this strategy should be examined in transition cows.

Dietary fiber and milk yield, mastication, digestion, and the rate of passage in goats fed alfalfa hay

Two experiments were conducted to study the effect of intake of fiber on productive performance of high producing dairy goats during early to midlactation. Four dietary treatments were isonitrogenous and consisted of combinations of chopped alfalfa hay and concentrate, yielding 14, 18, 22, and 26% ADF. In Experiment 1, 40 multiparous Alpine does were used in a completely randomized block design. Milk fat content and total chewing time increased, and milk yield tended to decrease, as dietary ADF intake increased. Chewing efficiency [min/(g x kg BW.75)] for DM decreased, whereas that for ADF increased as ADF intake increased. Prediction equations were the following: milk fat yield, g/d = 115.78 - .128 x ADF intake, g/d + .00021 X (ADF intake)2 (r = .55); total chewing time, min/d = 345.33 + .32 x ADF intake, g/d (r = .60). In Experiment 2, 20 does were used in a completely randomized design. Apparent digestibilities of DM and energy decreased as dietary ADF intake increased. Rumen turnover rate and transit time of liquid were affected by ADF intake. Transit time of hay decreased as ADF intake increased. Intake of ADF affected pH and ammonia, acetate, and butyrate concentrations in the rumen. Acetate to propionate ration increased with ADF intake. No apparent trends were observed in whole blood beta-hydroxybutyrate or in plasma NEFA concentrations related to ADF intake. It appeared that DMI and milk fat yield leveled at 22% ADF or 43% NDF. For lactating dairy goats producing more than 3.5 kg/d of milk, calculated fat output reached a plateau when they consumed 587 g/d of ADF and spent 512 min/d chewing.