Milk production and grazing behaviour responses of Alpine dairy goats to daily access time to pasture or to daily pasture allowance on temperate pastures in spring

Dairy goat performance in two grazing regimes: silvopastoral rangeland or abandoned agricultural land, and two supplementation treatments in central Mexico

Twenty Saanen third parturition dairy goats were used in an on-farm 2 × 2 factorial arrangement that ran for 12 weeks, with two grazing regimes and two concentrate types. The grazing regimes evaluated were an extensive silvopastoral native rangeland (SPR) and grazing in an abandoned agricultural land (AAL). Grazing happened between 9:00 and 17:00 h. The two types of concentrate supplement were a high protein concentrate (HP = 180 g CP/kg DM and 13 MJ ME/kg DM) or high energy concentrate (HE = 110  g CP/kg DM and 14.3 MJ ME/kg DM). Goats were milked once a day, providing 250 g of concentrate supplement per goat and day. Animal variables were fat and protein corrected milk yield recorded every day, and milk composition determined for two consecutive days at the end of each experimental week. Flora in the experimental paddocks was characerised and sampled, including grasses, shrubs, trees, legumes and cacti. The data was analysed with the R software using a mixed model with day nested in period as random effect and goat as repeated measure. The SPR had greater (P = 0.002) fat and protein corrected milk yield than AAL, with no differences between concentrate type and no interaction (P > 0.05). There was an interaction (P < 0.01) between grazing regime and concentrate type for fat content in milk, where a reduction in fat content was notorious in the SPR regime. Protein content of milk was greater (P < 0.01) in SPR with no significant effects of concentrate type or the interaction. The number of plant species in SPR was greater. The native silvopastoral system supplemented with the high energy concentrate was the strategy with higher milk yield, and protein and milk fat content, although the interaction between grazing regime and supplement was significant only for milk fat content.

Drinking water intake, milk production, and grazing behaviour of alpine dairy goats in response to daytime water restriction on temperate pastures

Certain local breeds of goats have adapted to severe water restriction in arid and semi-arid regions, but little is known about the adaptability of high-producing dairy goats to water restriction while grazing under temperate conditions. The aim of this study was to assess effects of water restriction of lactating Alpine goats during the daytime at pasture (8 h/d) on herd-level drinking water intake and individual milk production and grazing time. Goats remained in the barn between evening and morning milkings, where each animal was offered 600 g of concentrate and 400 g of hay each day, with free access to water. Twenty four goats were used in a crossover design, for two consecutive 14-d periods. The study was conducted in early summer, with a daily mean ambient temperature of 18.2 ± 3.5 °C (range of 13-27 °C over all the study days), a mean temperature-humidity index of 64 ± 4.9 (range of 56-76). Goats had access to a high-quality multispecies pasture with a mean of 216 ± 44 g DM/kg fresh matter. Total drinking water intake averaged 5.57 L/d and did not differ significantly between treatments. Goats with water access at pasture drank a mean of 1.88 L of water per day during the grazing period, but drank 2.24 L less per day in the barn than goats without water access at pasture. Drinking water intake increased by 0.57 L per day for each °C increase in daily mean ambient temperature. Daily milk production, milk composition, body weight, and daily grazing time did not differ between treatments. Only the duration of the first morning meal at pasture differed significantly between treatments. Thus, water restriction for 8 h per day during grazing periods does not seem to influence the variables measured for Alpine dairy goats under temperate conditions.

Intake, milk yield and grazing behaviour of strip-grazing Alpine dairy goats in response to daily pasture allowance

Grazing management has an important impact on dairy ruminants' performance. References on the intake and milk yield of dairy goats under strip-grazing systems in temperate regions are scarce. In order to study the effect of pasture allowance on pasture intake (PI), milk yield and grazing behaviour, a trial was carried out in spring with 36 Alpine goats in mid-lactation. Three daily pasture allowances (PA=1.7, 2.6 and 3.5 kg dry matter (DM)/day, namely Low, Medium and High, respectively) were compared in a 3 × 3 Latin square design replicated six times during three successive 14-day periods. Goats individually received 268 g DM of concentrate twice daily at each milking and had access 11 h/day to pasture (from 0830 to 1600 h and from 1730 to 2100 h). Pasture intake increased with PA, and more so between Low and Medium than between Medium and High (+216 v. +101 g DM/kg DM of PA). Milk yield was lower on Low than on Medium and High (2.79 v. 3.13 kg/day), as were milk fat and protein yields. Grazing time averaged 476 min/day and was lowest on Low and greatest on Medium. Pasture intake rate was 30 g DM/h lower on Low and Medium than on High. It is concluded that under temperate conditions, when goats are supplemented with 536 g DM of concentrate and have enough access time to pasture (11 h/day), a medium pasture allowance close to 2.6 kg DM/day may be sufficient to maximise milk yield.

Effects of forage species and feeding systems on rumen fermentation, microbiota and conjugated linoleic acid content in dairy goats

The objective of this experiment was to investigate the effects of forage species and feeding systems on ruminal fermentation, microbiota (Butyrivibrio fibrisolvens, Fibrobacter succinogenes and total bacteria) and conjugated linoleic acid (CLA) concentration of milk in dairy goats. Twenty female crossbred Saanen lactating goats (~35 ± 3.0 kg bodyweight) in early to mid-lactation stage were assigned to a 45-day completely randomised-design feeding experiment, with the following four forage (roughage) treatments: cut-and-carry grass (CG), grazing of grass (GG), cut-and-carry leucaena (CL) and grazing of leucaena (GL; n = 5). All animals were given concentrate equivalent to 1.5% of their bodyweight. The grass used in the study was napier Pak Chong 1 grass (Pennisetum purpureum × Pennisetum americanum hybrid). The results showed that irrespective of the type of forage, grazing goats (GG and GL) had a higher (P &lt; 0.05) forage intake and, thus, total dry-matter and crude-protein intakes than did those fed indoors (CG and CL). However, the intake of C18:2n6 and particularly of C18:3n3 was generally higher for grass-fed goats than for leucaena-fed goats. Treatments did not exert significant differences on rumen fermentation characteristics. However, the populations of B. fibrisolvens, F. succinogenes and total bacteria were significantly (P &lt; 0.05) higher in grazing goats (GG and GL) than in their counterparts fed with the cut-and-carry system (CG and CL). Goats in the grazing system also had a higher (P &lt; 0.05) milk yield, and milk fat, c9, t11 CLA and omega-3 fatty acid concentrations than did those in the cut-and-carry system and only grazing goats produced detectable levels of t10, c12 CLA in milk. Putting the above together, it can be concluded that allowing dairy goats to outdoor grazing stimulates a higher forage intake, including that of C18:2n6 and C18:3n3, as well as enhancing population of B. fibrisolvens (involved in the synthesis of milk CLA), resulting in a higher milk yield, and enhances c9, t11 and t10, c12 CLA in goat milk.