Eight Murciano-Granadina dairy goats in late lactation were exposed to different ambient conditions, using metabolic cages in a climatic chamber. The experimental design was a crossover (2 periods of 35 d and 4 goats each) and conditions were (1) thermal neutral (TN; 15 to 20 °C day-night) and (2) heat stress (HS; 12-h day at 37 °C and 12-h night at 30.5 °C). Humidity was maintained at 40% and light-dark was constant (12-12h). The forage:concentrate ratio was adjusted daily for maintaining similar value in TN and HS goats (70:30). Water was freely available at ambient temperature. Rectal temperature and respiratory rate (0800, 1200 and 1700 h) and milk yield were recorded daily, whereas milk composition, nonesterified fatty acids and haptoglobin in blood were analyzed weekly. At d 25, additional blood samples were taken for analysis of metabolites and indicators of the acid-base balance. Digestibility coefficients and N balance were determined (d 31 to 35) and body weight was recorded (d 35). Compared with TN goats, HS goats experienced greater rectal temperature (+0.58 °C), respiratory rate (+48 breaths/min), water intake (+77%) and water evaporation (+207%). Intake of HS goats rapidly declined until d 7 (-40%), partially recovered from d 7 to 19, and steadied thereafter (-14%). No changes in digestibility or N balance were detected. Blood nonesterified fatty acids and haptoglobin peaked at d 7 in HS goats but did not vary thereafter. Although milk yield did not vary by treatment, milk of HS goats contained -12.5% protein and -11.5% casein than TN goats. Panting reduced concentration and pressure of CO₂ in the blood of HS goats, but they were able to maintain their blood pH similar to the TN group by lowering HCO₃(-) and increasing Cl(-) concentrations in their blood. In conclusion, HS dairy goats showed dramatic physiological changes during the first week of treatment and partially recovered thereafter. They were able to maintain milk yield by losing body mass, but milk protein content and protein yield were depressed. Further research is needed to assess the response of dairy goats to HS at earlier stages of lactation.

The effects of once (1X) vs. twice (2X) daily milking throughout lactation on milk yield, milk composition, somatic cell count (SCC), and udder health were studied in 32 Murciano-Granadina dairy goats. Goats were assigned at wk 2 of lactation to two treatment groups; once daily milking at 0900 (1X, n = 17), or twice daily milking at 0900 and 1700 (2X, n = 15). Milk yield was recorded weekly until wk 28, and milk composition and SCC were evaluated for each individual udder half at each milking at wk 2 and 4 of lactation and then, monthly until the end of the experiment. Once daily milking resulted in an 18% reduction in the yield of 4% fat-corrected milk compared to twice daily milking (1.61 vs. 1.95 L/d, respectively). This reduction was more marked from wk 2 to 12 than in mid and late lactation. Response to milking frequency also varied according to parity number where goats of less than four parities suffered more milk yield losses during 1X than older goats. Milk of 1X goats contained higher percentages of total solids (13.6 vs. 12.9%), fat (5.10 vs. 4.62%) and casein (2.57 vs. 2.35%) than milk of 2X goats, but milk protein percentage did not differ between treatments (3.28 vs. 3.20%). Yields of total solids, fat, protein and casein tended to be higher for 2X than 1X. Milk SCC did not differ between treatments. We conclude that application of once daily milking in Murciano-Granadina dairy goats moderately reduced milk yield without negative effects on milk composition and udder health. Losses in milk yield would be reduced if 1X is practiced during mid- or late lactation and in older goats. An increase in labor productivity and a higher farmer's standard of living is also expected.

A total of 24 Murciano-Granadina dairy goats milked once daily throughout lactation were used to study the effects of including soybean oil (SBO) in the diet on lactational performance and milk fatty acid (FA) content, particularly conjugated linoleic acid (CLA) and trans-vaccenic acid (trans-11 C18:1, TVA). Three weeks after parturition, goats were allocated to 2 balanced groups according to lactation number, body weight, and daily milk yield, and were kept in separate pens. The experiment consisted of a 2-period (28 d each) crossover with 2 dietary treatments: control and SBO (6% as fed in the concentrate). Goats were fed dehydrated fescue (ad libitum), alfalfa pellets (0.5 kg/d), and concentrate (1 kg/d) to which the SBO was or was not added. Forage was fed in the pens, and concentrate was fed individually in 2 equal portions at milking (0900 h) and in the afternoon (1700 h). Final SBO content in the consumed SBO diet was 2.5% (dry matter basis). Diets were isonitrogenous (17.4% crude protein), but their total FA content varied from 2.2% (control) to 4.6% (SBO). There was no effect of SBO on dry matter intake, milk yield, energy-corrected milk, body weight, or body condition score. Compared with the control diet, feeding SBO increased milk fat content (4.57 vs. 5.24%) and yield as well as total solids content. Soybean oil had no effect on milk crude and true protein contents, but it reduced milk casein content (2.48 vs. 2.34%). Short- and medium-chain FA decreased by feeding SBO, whereas long-chain FA increased. Feeding preformed linoleic acid through SBO increased milk concentrations of linoleic, oleic, and stearic FA but reduced levels of linolenic and palmitic FA. As a consequence, feeding SBO decreased the saturated-to-unsaturated FA ratio and the atherogenicity index. Compared with the control treatment, milk contents of cis-9, trans-11 CLA (0.68 vs. 2.03%) and TVA (2.04 vs. 6.41%) in the SBO treatment increased by approximately 200%. In conclusion, feeding a moderate dose of SBO to dairy goats was a useful way to increase milk fat, CLA, and TVA contents in milk and to reduce the atherogenicity index without negative effects on intake, milk yield, and protein content.

Four lactating Holstein cows (average milk yield: 20±3 l/d) were used to develop and validate a method for estimating the size of udder cisterns (Sinus lactiferi) using ultrasonography. A sectorial transducer probe of 5 MHz, placed in contact with the teat in a parallel cranial position, was used to obtain vertical scans of the udder in two perpendicular planes with the teat canal axis as reference. Udder scans for each udder quarter were taken randomly at intervals of 4, 8, 12, 16, 20 and 24 h after milking. Glandular parenchyma (echogenic) and lumen of the cisterns full of milk (anechogenic) were evident in the scans, the calculated area of the anechogenic portion being defined as cistern area. Cistern areas measured in perpendicular scans were highly correlated. Immediately after each measurement, cisternal milk was removed from each quarter using a teat cannula after i.v. injection of an oxytocin-receptor blocking agent. Alveolar milk from each quarter was then obtained by machine milking after i.m. injection of oxytocin. Cistern area and cisternal milk volume increased with length of milking interval showing a curvilinear pattern with a plateau after 16 h. Correlations between cistern area and cisternal milk volume were positive and significant (P<0·001) at all intervals but showed the highest values with the smallest residual standard deviations at 8 h (r=0·88) and 12 h (r=0·84). Since 8 h has previously been identified as a suitable time at which to determine cisternal milk volume for the purposes of defining suitability for different milking strategies, we conclude that ultrasonography provides a satisfactory, non-invasive method for determination of milk storage characteristics in dairy cows.

Data of 69 dairy sheep farms (70% Assaf and 30% Awassi crossbred), located in the Spanish Autonomous Community of Castilla y León and grouped for receiving technical advice, were used to study their structure and performance. Farm surface was 55.4ha, on average. Approximately 25% of the farms did not have cultivation land, and the other 75% had, on average, 73ha (from which 67% were devoted to forage). Farms used 2.1 annual work units (familiar, 90%), 493 ewes, and yielded 147,000 L/yr of milk. Farmers were tenant (84%), younger than 45 yr (70%), had new houses, and were grouped in cooperatives (83%). Sheep were fed indoors (occasional grazing only) in modern loose stalls and had machine milking. Planned mating (summer to fall) was done in 91% of farms (hormonal treatment, 54%) but artificial insemination was scarce (23%). Annual milk sales averaged 309 L/ewe (fat, 6.5%; protein, 5.3%; log(10) somatic cell count, 5.7), and milk was sent to local dairy industries for cheese production, and 1.35 lambs/ewe were harvested as milk-fed lambs (lechazo). Artificial lamb rearing was done in 38% of farms (automatic, 81%; manual, 19%). Total mixed rations were used in 33% of farms, and the rest used rationed concentrate (including self-produced cereals) according to physiological stage of the ewes (0.45 to 1.97 kg/d) and ad libitum forage (dehydrated, 70%; hay, 68%; fresh, 25%; silage, 12%). The concentrate-to-forage ratio ranged between 32 and 61%. In total, 68% of farms bought more than half of the forage, and 87% of them bought more than half of the required concentrates. According to structural, productive, and managerial traits, 4 types of farms were differentiated by using multiple correspondence analysis and cluster analysis. Type groups were: 1) large-surface farms, devoted to cereal and forage production, predominantly with Awassi crossbreed sheep and a high level of self-consumed commodities (12% of the farms); 2) large flocks with intermediate farm surfaces devoted to forage production and predominantly with Assaf sheep (30% of the farms); 3) high-yielding farms, with intermediate sized flocks of Assaf sheep and very intensive management (42% of the farms); and, 4) no-land farms predominantly with Assaf sheep (16% of the farms). In conclusion, the dairy sheep farms studied showed more adoption of intensive production systems than traditional farms, which resulted in higher milk and lamb yields. Despite all of them being based on familiar units, as traditional farms, they were highly dependent on external resources and became more vulnerable, faced with future uncertainties of the market.

Fourteen Murciano-Granadina dairy goats were used to evaluate udder compartments (cisternal and alveolar) and cisternal recoil after an oxytocin (OT) challenge at different milking intervals (8, 16, and 24 h) during wk 7 of lactation. Goats were milked once (1x; n = 7) or twice (2x; n = 7) daily from wk 2 of lactation. Average milk yields for wk 4 and 8 were 1.76 and 2.24 L/d, for goats milked 1x and 2x, respectively. For each half udder, cisternal area was measured by ultrasonography and cisternal milk was measured by machine milking after i.v. injection of an OT receptor blocking agent. Alveolar milk was then obtained after i.v. injection of OT. Regardless of milking frequency, alveolar milk increased from 8 to 16 h after milking, but did not change thereafter. Cisternal area and cisternal milk increased linearly (R2 = 0.96 to 0.99) up to 24 h, indicating continuous milk storage in the cistern at any alveoli filling degree. Cisternal to alveolar ratio increased with milking interval (from 57:43 to 75:25), but differences between milking intervals were significant at 8 h only, at which time goats milked 2x showed a greater ratio (1x = 51:49; 2x = 62:38). Despite extended milking intervals, cisterns of goats milked 1x did not become larger than cisterns of goats milked 2x after 5 wk of treatment. The highest correlation between cisternal area and cisternal milk was detected at 8 h after milking (r = 0.74). Primiparous goats had smaller cisternal areas and less cisternal milk than multiparous goats at all milking intervals. Cisternal recoil was studied in a sample of multiparous goats milked 1x (n = 4) and 2x (n = 4) by scanning cisterns by ultrasonography at 0, 5, 15, and 30 min after an OT challenge for each milking interval. Cisternal area increased after OT injection for the 8- and 16-h milking intervals, but no differences were observed for the 24-h interval. Unlike cows, no changes in cisternal area were observed after OT injection, indicating the absence of cisternal recoil in goats. We conclude that goats show a large cisternal compartment that increases linearly after milking. Nevertheless, cisternal size did not increased after 1x milking, probably because of lesser milk yield. Multiparous goats had larger cisterns than primiparous goats and were able to store more milk in their cisterns at all milking intervals. Because of the high capacity of goat cisterns, no milk return from cistern to alveoli is expected if milking is delayed after milk letdown.

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Twenty-four lactating ewes (Manchega, n = 12; Lacaune, n = 12) in mid lactation were used to assess the short-term effects of different machine milking intervals (4, 8, 12, 16, 20, and 24 h) on milk yield, milk composition, and tight junction (TJ) permeability of mammary epithelia. Milk samples were analyzed for chemical composition, somatic cell count (SCC), and plasmin activity. Plasma lactose, and milk Na and K concentrations were used as indicators of TJ permeability. Milk accumulated linearly for up to 24 h, showing a different rate according to the milk yield of the breed (Manchega, 38 mL/h; Lacaune, 87 mL/h). Milking interval affected milk fat content, which decreased markedly from 4 to 24 h in both breeds, but no differences were observed in milk protein content. The milk contents of casein, true protein, lactose, and total solids also varied according to milking interval. Values of SCC did not vary by breed (175 x 10(3) cells/mL, on average), showing the lowest log(10) values for the 4-and 24-h milking intervals in both breeds. Plasmin activity in milk increased with milking interval until 20 h of udder filling in both breeds, and was poorly but positively correlated with SCC content (r = 0.39). Plasma lactose increased dramatically after 20 h of milk accumulation, indicating enhanced permeability of mammary TJ. As a result, an increase in Na concentration and in the Na:K ratio, and a decrease in K concentration, were observed in the milk of Manchega ewes. On the contrary, no differences in Na and K concentrations in milk were detected in Lacaune ewes. In conclusion, our results proved that Manchega and Lacaune dairy sheep could maintain high rates of milk secretion during extended milking intervals in the short term, with no effects on udder health and few negative effects on milk yield. Increased TJ permeability, caused by the effect of udder filling, induced changes in milk composition that were more marked in Manchega than in Lacaune ewes.